[v4,1/4] Documentation: fpga: dfl: Add documentation for DFHv1

  From: Matthew Gerlach <matthew.gerlach@linux.intel.com>

Add documentation describing the extensions provided by Version
1 of the Device Feature Header (DFHv1).

Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
---
v4: Remove marketing speak and separate v0 and v1 descriptions.
    Fix errors reported by "make htmldocs".

v3: no change

v2: s/GUILD/GUID/
    add picture
---
 Documentation/fpga/dfl.rst | 96 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
  

On Thu, Oct 20, 2022 at 02:26:07PM -0700, matthew.gerlach@linux.intel.com wrote:
> +Device Feature Header - Version 0
> +===========================================
> +The format of Version 0 of a Device Feature Header (DFH) is shown below::
> +
> +    +-----------------------------------------------------------------------+
> +    |63 Type 60|59 DFH VER 52|51 Rsvd 41|40 EOL|39 Next 16|15 VER 12|11 ID 0| 0x00
> +    +-----------------------------------------------------------------------+
> +    |63                                 GUID_L                             0| 0x08
> +    +-----------------------------------------------------------------------+
> +    |63                                 GUID_H                             0| 0x10
> +    +-----------------------------------------------------------------------+
> +
> +Offset 0x00
> +Type - The type of DFH (e.g. FME, AFU, or private feature).
> +DFH VER - The version of the DFH.
> +Rsvd - Currently unused.
> +EOL - Set if this DFH is the end of the Device Feature List (DFL).
> +Next - The offset of the next DFH in the DFL from the start of the DFH.
> +If EOL is set, Next refers to size of mmio for last feature in the list.
> +ID - If Type field is 'private feature', then ID of the private feature.
> +
> +Offset 0x08
> +GUID_L - Least significant 64 bits of a 128 bit Globally Unique Identifier
> +if Type is FME or AFU.
> +
> +Offset 0x10
> +GUID_H - Most significant 64 bits of a 128 bit Globally Unique Identifier
> +if Type is FME or AFU.
> +
> +
> +Device Feature Header - Version 1
> +===========================================
> +The format of Version 1 of a Device Feature Header (DFH) is shown below::
> +
> +    +-----------------------------------------------------------------------+
> +    |63 Type 60|59 DFH VER 52|51 Rsvd 41|40 EOL|39 Next 16|15 VER 12|11 ID 0| 0x00
> +    +-----------------------------------------------------------------------+
> +    |63                                 GUID_L                             0| 0x08
> +    +-----------------------------------------------------------------------+
> +    |63                                 GUID_H                             0| 0x10
> +    +-----------------------------------------------------------------------+
> +    |63                 Address/Offset                            1|  Rel  0| 0x18
> +    +-----------------------------------------------------------------------+
> +    |63        Reg Size       32|Params 31|30 Group    16|15 Instance      0| 0x20
> +    +-----------------------------------------------------------------------+
> +    |63 Next      34|RSV33|EOP32|31 Param Version 16|15 Param ID           0| 0x28
> +    +-----------------------------------------------------------------------+
> +    |63                 Parameter Data                                     0| 0x30
> +    +-----------------------------------------------------------------------+
> +
> +                                  ...
> +
> +    +-----------------------------------------------------------------------+
> +    |63 Next parameter offset 32|31 Param Version 16|15 Param ID           0|
> +    +-----------------------------------------------------------------------+
> +    |63                 Parameter Data                                     0|
> +    +-----------------------------------------------------------------------+
> +
> +Offset 0x00
> +Type - The type of DFH (e.g. FME, AFU, or private feature).
> +DFH VER - The version of the DFH.
> +Rsvd - Currently unused.
> +EOL - Set if this DFH is the end of the Device Feature List (DFL).
> +Next - The offset of the next DFH in the DFL from the start of the DFH.
> +If EOL is set, Next refers to size of mmio for last feature in the list.
> +ID - If Type field is 'private feature', then ID of the private feature.
> +
> +Offset 0x08
> +GUID_L - Least significant 64 bits of a 128 bit Globally Unique Identifier.
> +
> +Offset 0x10
> +GUID_H - Most significant 64 bits of a 128 bit Globally Unique Identifier
> +if Type is FME or AFU.
> +
> +Offset 0x18
> +Address/Offset - If Rel bit is set, then high 63 bits of a 16 bit aligned
> +absolute address for the location of the feature's registers.
> +If Rel bit is clear, then the feature's registers start at the
> +offset from the start of the DFH.
> +
> +Offset 0x20
> +Reg Size - Size of feature's register set.
> +Params - Set if DFH has one or more parameter blocks.
> +Group - Id of group if feature is part of a group.
> +Instance - Id of instance of feature within a group.
> +
> +Offset 0x28 if feature has parameters
> +Next - High 30 bits of a 32 bit aligned offset to the next parameter block.
> +If EOP set, size of last parameter.
> +Param Version - Version of Param ID.
> +Param ID - ID of parameter.
> +
> +Offset 0x30
> +Parameter Data - Parameter data whose size and format is defined by version
> +and ID of the parameter.
> +

The offset fields list should be formatted with nested list (with
prose improv):

---- >8 ----

diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
index 12365be435a812..9c19ee62d4ac44 100644
--- a/Documentation/fpga/dfl.rst
+++ b/Documentation/fpga/dfl.rst
@@ -573,22 +573,27 @@ The format of Version 0 of a Device Feature Header (DFH) is shown below::
     |63                                 GUID_H                             0| 0x10
     +-----------------------------------------------------------------------+
 
-Offset 0x00
-Type - The type of DFH (e.g. FME, AFU, or private feature).
-DFH VER - The version of the DFH.
-Rsvd - Currently unused.
-EOL - Set if this DFH is the end of the Device Feature List (DFL).
-Next - The offset of the next DFH in the DFL from the start of the DFH.
-If EOL is set, Next refers to size of mmio for last feature in the list.
-ID - If Type field is 'private feature', then ID of the private feature.
+The fields are:
 
-Offset 0x08
-GUID_L - Least significant 64 bits of a 128 bit Globally Unique Identifier
-if Type is FME or AFU.
+  * Offset 0x00
 
-Offset 0x10
-GUID_H - Most significant 64 bits of a 128 bit Globally Unique Identifier
-if Type is FME or AFU.
+    * Type - The type of DFH (e.g. FME, AFU, or private feature).
+    * DFH VER - The version of the DFH.
+    * Rsvd - Currently unused.
+    * EOL - Set if this DFH is the end of the Device Feature List (DFL).
+
+    * Next - The offset of the next DFH in the DFL from the start of the DFH.
+      If EOL is set, Next refers to size of mmio for last feature in the list.
+
+    * ID - Private feature ID if Type is private feature.
+
+  * Offset 0x08
+
+    * GUID_L - Least significant half of a 128-bit GUID if Type is FME or AFU.
+
+  * Offset 0x10
+
+    * GUID_H - Most significant half of a 128-bit GUID if Type if FME or AFU.
 
 
 Device Feature Header - Version 1
@@ -619,43 +624,53 @@ The format of Version 1 of a Device Feature Header (DFH) is shown below::
     |63                 Parameter Data                                     0|
     +-----------------------------------------------------------------------+
 
-Offset 0x00
-Type - The type of DFH (e.g. FME, AFU, or private feature).
-DFH VER - The version of the DFH.
-Rsvd - Currently unused.
-EOL - Set if this DFH is the end of the Device Feature List (DFL).
-Next - The offset of the next DFH in the DFL from the start of the DFH.
-If EOL is set, Next refers to size of mmio for last feature in the list.
-ID - If Type field is 'private feature', then ID of the private feature.
+The fields are:
 
-Offset 0x08
-GUID_L - Least significant 64 bits of a 128 bit Globally Unique Identifier.
+  * Offset 0x00
 
-Offset 0x10
-GUID_H - Most significant 64 bits of a 128 bit Globally Unique Identifier
-if Type is FME or AFU.
+    * Type - The type of DFH (e.g. FME, AFU, or private feature).
+    * DFH VER - The version of the DFH.
+    * Rsvd - Currently unused.
+    * EOL - Set if this DFH is the end of the Device Feature List (DFL).
 
-Offset 0x18
-Address/Offset - If Rel bit is set, then high 63 bits of a 16 bit aligned
-absolute address for the location of the feature's registers.
-If Rel bit is clear, then the feature's registers start at the
-offset from the start of the DFH.
+    * Next - The offset of the next DFH in the DFL from the start of the DFH.
+      If EOL is set, Next refers to size of mmio for last feature in the list.
 
-Offset 0x20
-Reg Size - Size of feature's register set.
-Params - Set if DFH has one or more parameter blocks.
-Group - Id of group if feature is part of a group.
-Instance - Id of instance of feature within a group.
+    * ID - Private feature ID if Type is private feature.
 
-Offset 0x28 if feature has parameters
-Next - High 30 bits of a 32 bit aligned offset to the next parameter block.
-If EOP set, size of last parameter.
-Param Version - Version of Param ID.
-Param ID - ID of parameter.
+  * Offset 0x08
 
-Offset 0x30
-Parameter Data - Parameter data whose size and format is defined by version
-and ID of the parameter.
+    * GUID_L - Least significant half of a 128-bit GUID if Type is FME or APU.
+
+  * Offset 0x10
+
+    * GUID_H - Most significant half of a 128-bit GUID if Type is FME or AFU.
+
+  * Offset 0x18
+
+    * Address/Offset - If Rel bit is set, upper 63 bits of a 16-bit aligned
+      absolute address for the location of feature registers; otherwise
+      registers of the feature start at the offset from the start of the DFH.
+
+  * Offset 0x20
+
+    * Reg Size - Size of register set of the feature.
+    * Params - Set if DFH has one or more parameter blocks.
+    * Group - ID of group if the feature is part of a group.
+    * Instance - ID of instance of the feature within a group.
+
+  * Offset 0x28 (if the feature has parameters)
+
+    * Next - Upper 30 bits of a 32-bit aligned offset to the next parameter
+      block. If EOP is set, size of last parameter.
+
+    * Param Version - Version of Param ID.
+    * Param ID - ID of parameter.
+
+  * Offset 0x30 (if the feature has parameters)
+
+    * Parameter Data - Parameter data whose size and format is defined by
+      version and ID of the parameter.
 
 Open discussion
 ===============

Thanks.
  

On Thu, 20 Oct 2022, matthew.gerlach@linux.intel.com wrote:

> From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
> 
> Add documentation describing the extensions provided by Version
> 1 of the Device Feature Header (DFHv1).
> 
> Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
> ---
> v4: Remove marketing speak and separate v0 and v1 descriptions.
>     Fix errors reported by "make htmldocs".
> 
> v3: no change
> 
> v2: s/GUILD/GUID/
>     add picture
> ---
>  Documentation/fpga/dfl.rst | 96 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 96 insertions(+)
> 
> diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
> index 15b670926084..12365be435a8 100644
> --- a/Documentation/fpga/dfl.rst
> +++ b/Documentation/fpga/dfl.rst
> @@ -561,6 +561,102 @@ new DFL feature via UIO direct access, its feature id should be added to the
>  driver's id_table.
>  
>  
> +Device Feature Header - Version 0
> +===========================================
> +The format of Version 0 of a Device Feature Header (DFH) is shown below::
> +
> +    +-----------------------------------------------------------------------+
> +    |63 Type 60|59 DFH VER 52|51 Rsvd 41|40 EOL|39 Next 16|15 VER 12|11 ID 0| 0x00
> +    +-----------------------------------------------------------------------+
> +    |63                                 GUID_L                             0| 0x08
> +    +-----------------------------------------------------------------------+
> +    |63                                 GUID_H                             0| 0x10
> +    +-----------------------------------------------------------------------+
> +
> +Offset 0x00
> +Type - The type of DFH (e.g. FME, AFU, or private feature).
> +DFH VER - The version of the DFH.
> +Rsvd - Currently unused.
> +EOL - Set if this DFH is the end of the Device Feature List (DFL).
> +Next - The offset of the next DFH in the DFL from the start of the DFH.
> +If EOL is set, Next refers to size of mmio for last feature in the list.
> +ID - If Type field is 'private feature', then ID of the private feature.
> +
> +Offset 0x08
> +GUID_L - Least significant 64 bits of a 128 bit Globally Unique Identifier
> +if Type is FME or AFU.
> +
> +Offset 0x10
> +GUID_H - Most significant 64 bits of a 128 bit Globally Unique Identifier
> +if Type is FME or AFU.
> +
> +
> +Device Feature Header - Version 1
> +===========================================

While this is structurally better than the previous one. I'd still include
at least one paragraph about the purpose. Something along these lines 
(picked from v3 + edited the marketing speak/v0 compare away from it):

Version 1 of the Device Feature Header (DFHv1) provides flexibility and 
extensibility to hardware designs using Device Feature Lists. It is a
standardized mechanism for features to describe parameters/capabilities to 
software.

With DFHv1:
* GUID is mandatory for all types
* The register space of the feature is decoupled from the location of the DFH
* A list of parameter values associates to a particular feature.

After that, the header itself makes much more sense already.

> +The format of Version 1 of a Device Feature Header (DFH) is shown below::
> +
> +    +-----------------------------------------------------------------------+
> +    |63 Type 60|59 DFH VER 52|51 Rsvd 41|40 EOL|39 Next 16|15 VER 12|11 ID 0| 0x00
> +    +-----------------------------------------------------------------------+
> +    |63                                 GUID_L                             0| 0x08
> +    +-----------------------------------------------------------------------+
> +    |63                                 GUID_H                             0| 0x10
> +    +-----------------------------------------------------------------------+
> +    |63                 Address/Offset                            1|  Rel  0| 0x18

Should this mention it's addr/offs of registers? As is it's bit hard to 
figure out from the diagram w/o the extra description. I think you have 
plenty of space for adding that extra bit of info.

> +    +-----------------------------------------------------------------------+
> +    |63        Reg Size       32|Params 31|30 Group    16|15 Instance      0| 0x20
> +    +-----------------------------------------------------------------------+
> +    |63 Next      34|RSV33|EOP32|31 Param Version 16|15 Param ID           0| 0x28
> +    +-----------------------------------------------------------------------+
> +    |63                 Parameter Data                                     0| 0x30
> +    +-----------------------------------------------------------------------+
> +
> +                                  ...
> +
> +    +-----------------------------------------------------------------------+
> +    |63 Next parameter offset 32|31 Param Version 16|15 Param ID           0|
> +    +-----------------------------------------------------------------------+
> +    |63                 Parameter Data                                     0|
> +    +-----------------------------------------------------------------------+
> +
> +Offset 0x00
> +Type - The type of DFH (e.g. FME, AFU, or private feature).
> +DFH VER - The version of the DFH.
> +Rsvd - Currently unused.
> +EOL - Set if this DFH is the end of the Device Feature List (DFL).
> +Next - The offset of the next DFH in the DFL from the start of the DFH.
> +If EOL is set, Next refers to size of mmio for last feature in the list.
> +ID - If Type field is 'private feature', then ID of the private feature.
> +
> +Offset 0x08
> +GUID_L - Least significant 64 bits of a 128 bit Globally Unique Identifier.
> +
> +Offset 0x10
> +GUID_H - Most significant 64 bits of a 128 bit Globally Unique Identifier
> +if Type is FME or AFU.

A copy-paste error?

> +
> +Offset 0x18
> +Address/Offset - If Rel bit is set, then high 63 bits of a 16 bit aligned
> +absolute address for the location of the feature's registers.
> +If Rel bit is clear, then the feature's registers start at the
> +offset from the start of the DFH.
> +
> +Offset 0x20
> +Reg Size - Size of feature's register set.
> +Params - Set if DFH has one or more parameter blocks.
> +Group - Id of group if feature is part of a group.
> +Instance - Id of instance of feature within a group.
> +
> +Offset 0x28 if feature has parameters
> +Next - High 30 bits of a 32 bit aligned offset to the next parameter block.
> +If EOP set, size of last parameter.
> +Param Version - Version of Param ID.
> +Param ID - ID of parameter.
> +
> +Offset 0x30
> +Parameter Data - Parameter data whose size and format is defined by version
> +and ID of the parameter.

I'd reverse the order and say "ID and version" (kind of major thing 
first).

> +
>  Open discussion
>  ===============
>  FME driver exports one ioctl (DFL_FPGA_FME_PORT_PR) for partial reconfiguration
>
  

On Fri, 21 Oct 2022, Ilpo Järvinen wrote:

> On Thu, 20 Oct 2022, matthew.gerlach@linux.intel.com wrote:
> 
> > From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
> > 
> > Add documentation describing the extensions provided by Version
> > 1 of the Device Feature Header (DFHv1).
> > 
> > Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
> > ---
> > v4: Remove marketing speak and separate v0 and v1 descriptions.
> >     Fix errors reported by "make htmldocs".
> > 
> > v3: no change
> > 
> > v2: s/GUILD/GUID/
> >     add picture
> > ---
> >  Documentation/fpga/dfl.rst | 96 ++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 96 insertions(+)
> > 
> > diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
> > index 15b670926084..12365be435a8 100644
> > --- a/Documentation/fpga/dfl.rst
> > +++ b/Documentation/fpga/dfl.rst
> > @@ -561,6 +561,102 @@ new DFL feature via UIO direct access, its feature id should be added to the
> >  driver's id_table.
> >  
> >  
> > +Device Feature Header - Version 0
> > +===========================================
> > +The format of Version 0 of a Device Feature Header (DFH) is shown below::
> > +
> > +    +-----------------------------------------------------------------------+
> > +    |63 Type 60|59 DFH VER 52|51 Rsvd 41|40 EOL|39 Next 16|15 VER 12|11 ID 0| 0x00
> > +    +-----------------------------------------------------------------------+
> > +    |63                                 GUID_L                             0| 0x08
> > +    +-----------------------------------------------------------------------+
> > +    |63                                 GUID_H                             0| 0x10
> > +    +-----------------------------------------------------------------------+
> > +
> > +Offset 0x00
> > +Type - The type of DFH (e.g. FME, AFU, or private feature).
> > +DFH VER - The version of the DFH.
> > +Rsvd - Currently unused.
> > +EOL - Set if this DFH is the end of the Device Feature List (DFL).
> > +Next - The offset of the next DFH in the DFL from the start of the DFH.
> > +If EOL is set, Next refers to size of mmio for last feature in the list.
> > +ID - If Type field is 'private feature', then ID of the private feature.
> > +
> > +Offset 0x08
> > +GUID_L - Least significant 64 bits of a 128 bit Globally Unique Identifier
> > +if Type is FME or AFU.
> > +
> > +Offset 0x10
> > +GUID_H - Most significant 64 bits of a 128 bit Globally Unique Identifier
> > +if Type is FME or AFU.
> > +
> > +
> > +Device Feature Header - Version 1
> > +===========================================
> 
> While this is structurally better than the previous one. I'd still include
> at least one paragraph about the purpose. Something along these lines 
> (picked from v3 + edited the marketing speak/v0 compare away from it):
> 
> Version 1 of the Device Feature Header (DFHv1) provides flexibility and 
> extensibility to hardware designs using Device Feature Lists. It is a
> standardized mechanism for features to describe parameters/capabilities to 
> software.
> 
> With DFHv1:
> * GUID is mandatory for all types
> * The register space of the feature is decoupled from the location of the DFH
> * A list of parameter values associates to a particular feature.
> 
> After that, the header itself makes much more sense already.
> 
> > +The format of Version 1 of a Device Feature Header (DFH) is shown below::
> > +
> > +    +-----------------------------------------------------------------------+
> > +    |63 Type 60|59 DFH VER 52|51 Rsvd 41|40 EOL|39 Next 16|15 VER 12|11 ID 0| 0x00
> > +    +-----------------------------------------------------------------------+
> > +    |63                                 GUID_L                             0| 0x08
> > +    +-----------------------------------------------------------------------+
> > +    |63                                 GUID_H                             0| 0x10
> > +    +-----------------------------------------------------------------------+
> > +    |63                 Address/Offset                            1|  Rel  0| 0x18
> 
> Should this mention it's addr/offs of registers? As is it's bit hard to 
> figure out from the diagram w/o the extra description. I think you have 
> plenty of space for adding that extra bit of info.
> 
> > +    +-----------------------------------------------------------------------+
> > +    |63        Reg Size       32|Params 31|30 Group    16|15 Instance      0| 0x20
> > +    +-----------------------------------------------------------------------+
> > +    |63 Next      34|RSV33|EOP32|31 Param Version 16|15 Param ID           0| 0x28
> > +    +-----------------------------------------------------------------------+
> > +    |63                 Parameter Data                                     0| 0x30
> > +    +-----------------------------------------------------------------------+
> > +
> > +                                  ...
> > +
> > +    +-----------------------------------------------------------------------+
> > +    |63 Next parameter offset 32|31 Param Version 16|15 Param ID           0|

Copy-paste error on the next field.
  

On Fri, 21 Oct 2022, Bagas Sanjaya wrote:

> On Thu, Oct 20, 2022 at 02:26:07PM -0700, matthew.gerlach@linux.intel.com wrote:
>> +Device Feature Header - Version 0
>> +===========================================
>> +The format of Version 0 of a Device Feature Header (DFH) is shown below::
>> +
>> +    +-----------------------------------------------------------------------+
>> +    |63 Type 60|59 DFH VER 52|51 Rsvd 41|40 EOL|39 Next 16|15 VER 12|11 ID 0| 0x00
>> +    +-----------------------------------------------------------------------+
>> +    |63                                 GUID_L                             0| 0x08
>> +    +-----------------------------------------------------------------------+
>> +    |63                                 GUID_H                             0| 0x10
>> +    +-----------------------------------------------------------------------+
>> +
>> +Offset 0x00
>> +Type - The type of DFH (e.g. FME, AFU, or private feature).
>> +DFH VER - The version of the DFH.
>> +Rsvd - Currently unused.
>> +EOL - Set if this DFH is the end of the Device Feature List (DFL).
>> +Next - The offset of the next DFH in the DFL from the start of the DFH.
>> +If EOL is set, Next refers to size of mmio for last feature in the list.
>> +ID - If Type field is 'private feature', then ID of the private feature.
>> +
>> +Offset 0x08
>> +GUID_L - Least significant 64 bits of a 128 bit Globally Unique Identifier
>> +if Type is FME or AFU.
>> +
>> +Offset 0x10
>> +GUID_H - Most significant 64 bits of a 128 bit Globally Unique Identifier
>> +if Type is FME or AFU.
>> +
>> +
>> +Device Feature Header - Version 1
>> +===========================================
>> +The format of Version 1 of a Device Feature Header (DFH) is shown below::
>> +
>> +    +-----------------------------------------------------------------------+
>> +    |63 Type 60|59 DFH VER 52|51 Rsvd 41|40 EOL|39 Next 16|15 VER 12|11 ID 0| 0x00
>> +    +-----------------------------------------------------------------------+
>> +    |63                                 GUID_L                             0| 0x08
>> +    +-----------------------------------------------------------------------+
>> +    |63                                 GUID_H                             0| 0x10
>> +    +-----------------------------------------------------------------------+
>> +    |63                 Address/Offset                            1|  Rel  0| 0x18
>> +    +-----------------------------------------------------------------------+
>> +    |63        Reg Size       32|Params 31|30 Group    16|15 Instance      0| 0x20
>> +    +-----------------------------------------------------------------------+
>> +    |63 Next      34|RSV33|EOP32|31 Param Version 16|15 Param ID           0| 0x28
>> +    +-----------------------------------------------------------------------+
>> +    |63                 Parameter Data                                     0| 0x30
>> +    +-----------------------------------------------------------------------+
>> +
>> +                                  ...
>> +
>> +    +-----------------------------------------------------------------------+
>> +    |63 Next parameter offset 32|31 Param Version 16|15 Param ID           0|
>> +    +-----------------------------------------------------------------------+
>> +    |63                 Parameter Data                                     0|
>> +    +-----------------------------------------------------------------------+
>> +
>> +Offset 0x00
>> +Type - The type of DFH (e.g. FME, AFU, or private feature).
>> +DFH VER - The version of the DFH.
>> +Rsvd - Currently unused.
>> +EOL - Set if this DFH is the end of the Device Feature List (DFL).
>> +Next - The offset of the next DFH in the DFL from the start of the DFH.
>> +If EOL is set, Next refers to size of mmio for last feature in the list.
>> +ID - If Type field is 'private feature', then ID of the private feature.
>> +
>> +Offset 0x08
>> +GUID_L - Least significant 64 bits of a 128 bit Globally Unique Identifier.
>> +
>> +Offset 0x10
>> +GUID_H - Most significant 64 bits of a 128 bit Globally Unique Identifier
>> +if Type is FME or AFU.
>> +
>> +Offset 0x18
>> +Address/Offset - If Rel bit is set, then high 63 bits of a 16 bit aligned
>> +absolute address for the location of the feature's registers.
>> +If Rel bit is clear, then the feature's registers start at the
>> +offset from the start of the DFH.
>> +
>> +Offset 0x20
>> +Reg Size - Size of feature's register set.
>> +Params - Set if DFH has one or more parameter blocks.
>> +Group - Id of group if feature is part of a group.
>> +Instance - Id of instance of feature within a group.
>> +
>> +Offset 0x28 if feature has parameters
>> +Next - High 30 bits of a 32 bit aligned offset to the next parameter block.
>> +If EOP set, size of last parameter.
>> +Param Version - Version of Param ID.
>> +Param ID - ID of parameter.
>> +
>> +Offset 0x30
>> +Parameter Data - Parameter data whose size and format is defined by version
>> +and ID of the parameter.
>> +
>
> The offset fields list should be formatted with nested list (with
> prose improv):
>
> ---- >8 ----

Thanks for the good suggestion.

>
> diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
> index 12365be435a812..9c19ee62d4ac44 100644
> --- a/Documentation/fpga/dfl.rst
> +++ b/Documentation/fpga/dfl.rst
> @@ -573,22 +573,27 @@ The format of Version 0 of a Device Feature Header (DFH) is shown below::
>     |63                                 GUID_H                             0| 0x10
>     +-----------------------------------------------------------------------+
>
> -Offset 0x00
> -Type - The type of DFH (e.g. FME, AFU, or private feature).
> -DFH VER - The version of the DFH.
> -Rsvd - Currently unused.
> -EOL - Set if this DFH is the end of the Device Feature List (DFL).
> -Next - The offset of the next DFH in the DFL from the start of the DFH.
> -If EOL is set, Next refers to size of mmio for last feature in the list.
> -ID - If Type field is 'private feature', then ID of the private feature.
> +The fields are:
>
> -Offset 0x08
> -GUID_L - Least significant 64 bits of a 128 bit Globally Unique Identifier
> -if Type is FME or AFU.
> +  * Offset 0x00
>
> -Offset 0x10
> -GUID_H - Most significant 64 bits of a 128 bit Globally Unique Identifier
> -if Type is FME or AFU.
> +    * Type - The type of DFH (e.g. FME, AFU, or private feature).
> +    * DFH VER - The version of the DFH.
> +    * Rsvd - Currently unused.
> +    * EOL - Set if this DFH is the end of the Device Feature List (DFL).
> +
> +    * Next - The offset of the next DFH in the DFL from the start of the DFH.
> +      If EOL is set, Next refers to size of mmio for last feature in the list.
> +
> +    * ID - Private feature ID if Type is private feature.
> +
> +  * Offset 0x08
> +
> +    * GUID_L - Least significant half of a 128-bit GUID if Type is FME or AFU.
> +
> +  * Offset 0x10
> +
> +    * GUID_H - Most significant half of a 128-bit GUID if Type if FME or AFU.
>
>
> Device Feature Header - Version 1
> @@ -619,43 +624,53 @@ The format of Version 1 of a Device Feature Header (DFH) is shown below::
>     |63                 Parameter Data                                     0|
>     +-----------------------------------------------------------------------+
>
> -Offset 0x00
> -Type - The type of DFH (e.g. FME, AFU, or private feature).
> -DFH VER - The version of the DFH.
> -Rsvd - Currently unused.
> -EOL - Set if this DFH is the end of the Device Feature List (DFL).
> -Next - The offset of the next DFH in the DFL from the start of the DFH.
> -If EOL is set, Next refers to size of mmio for last feature in the list.
> -ID - If Type field is 'private feature', then ID of the private feature.
> +The fields are:
>
> -Offset 0x08
> -GUID_L - Least significant 64 bits of a 128 bit Globally Unique Identifier.
> +  * Offset 0x00
>
> -Offset 0x10
> -GUID_H - Most significant 64 bits of a 128 bit Globally Unique Identifier
> -if Type is FME or AFU.
> +    * Type - The type of DFH (e.g. FME, AFU, or private feature).
> +    * DFH VER - The version of the DFH.
> +    * Rsvd - Currently unused.
> +    * EOL - Set if this DFH is the end of the Device Feature List (DFL).
>
> -Offset 0x18
> -Address/Offset - If Rel bit is set, then high 63 bits of a 16 bit aligned
> -absolute address for the location of the feature's registers.
> -If Rel bit is clear, then the feature's registers start at the
> -offset from the start of the DFH.
> +    * Next - The offset of the next DFH in the DFL from the start of the DFH.
> +      If EOL is set, Next refers to size of mmio for last feature in the list.
>
> -Offset 0x20
> -Reg Size - Size of feature's register set.
> -Params - Set if DFH has one or more parameter blocks.
> -Group - Id of group if feature is part of a group.
> -Instance - Id of instance of feature within a group.
> +    * ID - Private feature ID if Type is private feature.
>
> -Offset 0x28 if feature has parameters
> -Next - High 30 bits of a 32 bit aligned offset to the next parameter block.
> -If EOP set, size of last parameter.
> -Param Version - Version of Param ID.
> -Param ID - ID of parameter.
> +  * Offset 0x08
>
> -Offset 0x30
> -Parameter Data - Parameter data whose size and format is defined by version
> -and ID of the parameter.
> +    * GUID_L - Least significant half of a 128-bit GUID if Type is FME or APU.
> +
> +  * Offset 0x10
> +
> +    * GUID_H - Most significant half of a 128-bit GUID if Type is FME or AFU.
> +
> +  * Offset 0x18
> +
> +    * Address/Offset - If Rel bit is set, upper 63 bits of a 16-bit aligned
> +      absolute address for the location of feature registers; otherwise
> +      registers of the feature start at the offset from the start of the DFH.
> +
> +  * Offset 0x20
> +
> +    * Reg Size - Size of register set of the feature.
> +    * Params - Set if DFH has one or more parameter blocks.
> +    * Group - ID of group if the feature is part of a group.
> +    * Instance - ID of instance of the feature within a group.
> +
> +  * Offset 0x28 (if the feature has parameters)
> +
> +    * Next - Upper 30 bits of a 32-bit aligned offset to the next parameter
> +      block. If EOP is set, size of last parameter.
> +
> +    * Param Version - Version of Param ID.
> +    * Param ID - ID of parameter.
> +
> +  * Offset 0x30 (if the feature has parameters)
> +
> +    * Parameter Data - Parameter data whose size and format is defined by
> +      version and ID of the parameter.
>
> Open discussion
> ===============
>
> Thanks.
>
> -- 
> An old man doll... just what I always wanted! - Clara
>