diff mbox series

[v1] dt-bindings: riscv: explicitly mention assumption of Zicsr & Zifencei support

Message ID 20230427-fence-blurred-c92fb69d4137@wendy
State New
Headers
Series [v1] dt-bindings: riscv: explicitly mention assumption of Zicsr & Zifencei support |

Commit Message

Conor Dooley April 27, 2023, 10:43 a.m. UTC 
  The dt-binding was defined before the extraction of csr access and
fence.i into their own extensions, and thus the presence of the I
base extension implies Zicsr and Zifencei.
There's no harm in adding them obviously, but for backwards
compatibility with DTs that existed prior to that extraction, software
is unable to differentiate between "i" and "i_zicsr_zifencei" without
any further information.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
CC: Conor Dooley <conor@kernel.org>
CC: Rob Herring <robh+dt@kernel.org>
CC: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
CC: Paul Walmsley <paul.walmsley@sifive.com>
CC: Palmer Dabbelt <palmer@dabbelt.com>
CC: linux-riscv@lists.infradead.org
CC: devicetree@vger.kernel.org
CC: linux-kernel@vger.kernel.org
---
 Documentation/devicetree/bindings/riscv/cpus.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Rob Herring April 27, 2023, 5:39 p.m. UTC | #1 
On Thu, 27 Apr 2023 11:43:42 +0100, Conor Dooley wrote:
> The dt-binding was defined before the extraction of csr access and
> fence.i into their own extensions, and thus the presence of the I
> base extension implies Zicsr and Zifencei.
> There's no harm in adding them obviously, but for backwards
> compatibility with DTs that existed prior to that extraction, software
> is unable to differentiate between "i" and "i_zicsr_zifencei" without
> any further information.
> 
> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
> ---
> CC: Conor Dooley <conor@kernel.org>
> CC: Rob Herring <robh+dt@kernel.org>
> CC: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
> CC: Paul Walmsley <paul.walmsley@sifive.com>
> CC: Palmer Dabbelt <palmer@dabbelt.com>
> CC: linux-riscv@lists.infradead.org
> CC: devicetree@vger.kernel.org
> CC: linux-kernel@vger.kernel.org
> ---
>  Documentation/devicetree/bindings/riscv/cpus.yaml | 6 ++++++
>  1 file changed, 6 insertions(+)
> 

Acked-by: Rob Herring <robh@kernel.org>
Palmer Dabbelt May 2, 2023, midnight UTC | #2 
On Thu, 27 Apr 2023 03:43:42 PDT (-0700), Conor Dooley wrote:
> The dt-binding was defined before the extraction of csr access and
> fence.i into their own extensions, and thus the presence of the I
> base extension implies Zicsr and Zifencei.
> There's no harm in adding them obviously, but for backwards
> compatibility with DTs that existed prior to that extraction, software
> is unable to differentiate between "i" and "i_zicsr_zifencei" without
> any further information.
>
> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
> ---
> CC: Conor Dooley <conor@kernel.org>
> CC: Rob Herring <robh+dt@kernel.org>
> CC: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
> CC: Paul Walmsley <paul.walmsley@sifive.com>
> CC: Palmer Dabbelt <palmer@dabbelt.com>
> CC: linux-riscv@lists.infradead.org
> CC: devicetree@vger.kernel.org
> CC: linux-kernel@vger.kernel.org
> ---
>  Documentation/devicetree/bindings/riscv/cpus.yaml | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
> index 4c7ce4a37052..a93bc7eae928 100644
> --- a/Documentation/devicetree/bindings/riscv/cpus.yaml
> +++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
> @@ -85,6 +85,12 @@ properties:
>        User-Level ISA document, available from
>        https://riscv.org/specifications/
>
> +      Due to revisions of the ISA specification, some deviations
> +      have arisen over time.
> +      Notably, riscv,isa was defined prior to the creation of the
> +      Zicsr and Zifencei extensions and thus "i" implies
> +      "zicsr_zifencei".

also Zihpm and Zicntr.  I'm going to put this one on for-next, though.

Thanks!

> +
>        While the isa strings in ISA specification are case
>        insensitive, letters in the riscv,isa string must be all
>        lowercase to simplify parsing.
Palmer Dabbelt May 2, 2023, 12:19 a.m. UTC | #3 
On Thu, 27 Apr 2023 11:43:42 +0100, Conor Dooley wrote:
> The dt-binding was defined before the extraction of csr access and
> fence.i into their own extensions, and thus the presence of the I
> base extension implies Zicsr and Zifencei.
> There's no harm in adding them obviously, but for backwards
> compatibility with DTs that existed prior to that extraction, software
> is unable to differentiate between "i" and "i_zicsr_zifencei" without
> any further information.
> 
> [...]

Applied, thanks!

[1/1] dt-bindings: riscv: explicitly mention assumption of Zicsr & Zifencei support
      https://git.kernel.org/palmer/c/41ebfc91f785

Best regards,
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
index 4c7ce4a37052..a93bc7eae928 100644
--- a/Documentation/devicetree/bindings/riscv/cpus.yaml
+++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
@@ -85,6 +85,12 @@  properties:
       User-Level ISA document, available from
       https://riscv.org/specifications/
 
+      Due to revisions of the ISA specification, some deviations
+      have arisen over time.
+      Notably, riscv,isa was defined prior to the creation of the
+      Zicsr and Zifencei extensions and thus "i" implies
+      "zicsr_zifencei".
+
       While the isa strings in ISA specification are case
       insensitive, letters in the riscv,isa string must be all
       lowercase to simplify parsing.