diff mbox series

[V10,4/4] PCI: vmd: Add quirk to configure PCIe ASPM and LTR

Message ID 20230120031522.2304439-5-david.e.box@linux.intel.com
State New
Headers
Series Enable PCIe ASPM and LTR on select hardware |

Commit Message

David E. Box Jan. 20, 2023, 3:15 a.m. UTC 
  PCIe ports reserved for VMD use are not visible to BIOS and therefore not
configured to enable PCIe ASPM or LTR values (which BIOS will configure if
they are not set). Lack of this programming results in high power
consumption on laptops as reported in bugzilla.  For affected products use
pci_enable_link_state to set the allowed link states for devices on the
root ports. Also set the LTR value to the maximum value needed for the SoC.

This is a workaround for products from Rocket Lake through Alder Lake.
Raptor Lake, the latest product at this time, has already implemented LTR
configuring in BIOS. Future products will move ASPM configuration back to
BIOS as well.  As this solution is intended for laptops, support is not
added for hotplug or for devices downstream of a switch on the root port.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=212355
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215063
Link: https://bugzilla.kernel.org/show_bug.cgi?id=213717

Signed-off-by: Michael Bottini <michael.a.bottini@linux.intel.com>
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Jon Derrick <jonathan.derrick@linux.dev>
Reviewed-by: Nirmal Patel <nirmal.patel@linux.intel.com>
---
 V10
  - No change
 V9
  - Added BIOS quirk flag to VMD_FEATS_CLIENT flag, suggested by Sathya.
 V8
  - Removed struct vmd_device_data patch. Instead use #define for the LTR
    value which is the same across all products needing the quirk.
 V7
  - No change
 V6
  - Set ASPM first before setting LTR. This is needed because some
    devices may only have LTR set by BIOS and not ASPM
  - Skip setting the LTR if the current LTR in non-zero.
 V5
  - Provide the LTR value as driver data.
  - Use DWORD for the config space write to avoid PCI WORD access bug.
  - Set ASPM links firsts, enabling all link states, before setting a
    default LTR if the capability is present
  - Add kernel message that VMD is setting the device LTR.
 V4
  - Refactor vmd_enable_apsm() to exit early, making the lines shorter
    and more readable. Suggested by Christoph.
 V3
  - No changes
 V2
  - Use return status to print pci_info message if ASPM cannot be enabled.
  - Add missing static declaration, caught by lkp@intel.com

 drivers/pci/controller/vmd.c | 55 +++++++++++++++++++++++++++++++++++-
 1 file changed, 54 insertions(+), 1 deletion(-)

Comments

Ville Syrjälä March 20, 2023, 10:56 p.m. UTC | #1 
On Thu, Jan 19, 2023 at 07:15:22PM -0800, David E. Box wrote:
> +/*
> + * Enable ASPM and LTR settings on devices that aren't configured by BIOS.
> + */
> +static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
> +{
> +	unsigned long features = *(unsigned long *)userdata;
> +	u16 ltr = VMD_BIOS_PM_QUIRK_LTR;
> +	u32 ltr_reg;
> +	int pos;
> +
> +	if (!(features & VMD_FEAT_BIOS_PM_QUIRK))
> +		return 0;
> +
> +	pci_enable_link_state(pdev, PCIE_LINK_STATE_ALL);

Hi,

This is tripping lockdep on one our CI ADL machines.

https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_12814/bat-adlp-6/boot0.txt

<4>[   13.815380] ============================================
<4>[   13.815382] WARNING: possible recursive locking detected
<4>[   13.815384] 6.3.0-rc1-CI_DRM_12814-g4753bbc2a817+ #1 Not tainted
<4>[   13.815386] --------------------------------------------
<4>[   13.815387] swapper/0/1 is trying to acquire lock:
<4>[   13.815389] ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at: pci_enable_link_state+0x69/0x1d0
<4>[   13.815396] 
                  but task is already holding lock:
<4>[   13.815398] ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at: pci_walk_bus+0x24/0x90
<4>[   13.815403] 
                  other info that might help us debug this:
<4>[   13.815404]  Possible unsafe locking scenario:

<4>[   13.815406]        CPU0
<4>[   13.815407]        ----
<4>[   13.815408]   lock(pci_bus_sem);
<4>[   13.815410]   lock(pci_bus_sem);
<4>[   13.815411] 
                   *** DEADLOCK ***

<4>[   13.815413]  May be due to missing lock nesting notation

<4>[   13.815414] 2 locks held by swapper/0/1:
<4>[   13.815416]  #0: ffff8881029511b8 (&dev->mutex){....}-{3:3}, at: __driver_attach+0xab/0x180
<4>[   13.815422]  #1: ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at: pci_walk_bus+0x24/0x90
<4>[   13.815426] 
                  stack backtrace:
<4>[   13.815428] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.3.0-rc1-CI_DRM_12814-g4753bbc2a817+ #1
<4>[   13.815431] Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-P DDR4 RVP, BIOS ADLPFWI1.R00.3135.A00.2203251419 03/25/2022
<4>[   13.815434] Call Trace:
<4>[   13.815436]  <TASK>
<4>[   13.815437]  dump_stack_lvl+0x64/0xb0
<4>[   13.815443]  __lock_acquire+0x9b5/0x2550
<4>[   13.815461]  lock_acquire+0xd7/0x330
<4>[   13.815463]  ? pci_enable_link_state+0x69/0x1d0
<4>[   13.815466]  down_read+0x3d/0x180
<4>[   13.815480]  ? pci_enable_link_state+0x69/0x1d0
<4>[   13.815482]  pci_enable_link_state+0x69/0x1d0
<4>[   13.815485]  ? __pfx_vmd_pm_enable_quirk+0x10/0x10
<4>[   13.815488]  vmd_pm_enable_quirk+0x49/0xb0
<4>[   13.815490]  pci_walk_bus+0x6d/0x90
<4>[   13.815492]  vmd_probe+0x75f/0x9d0
<4>[   13.815495]  pci_device_probe+0x95/0x120
<4>[   13.815498]  really_probe+0x164/0x3c0
<4>[   13.815500]  ? __pfx___driver_attach+0x10/0x10
<4>[   13.815503]  __driver_probe_device+0x73/0x170
<4>[   13.815506]  driver_probe_device+0x19/0xa0
<4>[   13.815508]  __driver_attach+0xb6/0x180
<4>[   13.815511]  ? __pfx___driver_attach+0x10/0x10
<4>[   13.815513]  bus_for_each_dev+0x77/0xd0
<4>[   13.815516]  bus_add_driver+0x114/0x210
<4>[   13.815518]  driver_register+0x5b/0x110
<4>[   13.815520]  ? __pfx_vmd_drv_init+0x10/0x10
<4>[   13.815523]  do_one_initcall+0x57/0x330
<4>[   13.815527]  kernel_init_freeable+0x181/0x3a0
<4>[   13.815529]  ? __pfx_kernel_init+0x10/0x10
<4>[   13.815532]  kernel_init+0x15/0x120
<4>[   13.815534]  ret_from_fork+0x29/0x50
<4>[   13.815537]  </TASK>
David E. Box March 21, 2023, 2:24 a.m. UTC | #2 
Hi,

On Tue, 2023-03-21 at 00:56 +0200, Ville Syrjälä wrote:
> On Thu, Jan 19, 2023 at 07:15:22PM -0800, David E. Box wrote:
> > +/*
> > + * Enable ASPM and LTR settings on devices that aren't configured by BIOS.
> > + */
> > +static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
> > +{
> > +       unsigned long features = *(unsigned long *)userdata;
> > +       u16 ltr = VMD_BIOS_PM_QUIRK_LTR;
> > +       u32 ltr_reg;
> > +       int pos;
> > +
> > +       if (!(features & VMD_FEAT_BIOS_PM_QUIRK))
> > +               return 0;
> > +
> > +       pci_enable_link_state(pdev, PCIE_LINK_STATE_ALL);

We call pci_enable_link_state from a callback that's run during pci_walk_bus()
which I see already acquires the semaphore. We've had this patch for well over a
year and I haven't seen this issue before. Is there a particular config needed
to reproduce it?

As far as a solution I think we can copy what __pci_disable_link_state() does
and add a bool argument so that we only do down/up on the semaphore when set to
true. Since we know we will in be the lock during the bus walk we can set it to
false.

David

> 
> Hi,
> 
> This is tripping lockdep on one our CI ADL machines.
> 
> https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_12814/bat-adlp-6/boot0.txt
> 
> <4>[   13.815380] ============================================
> <4>[   13.815382] WARNING: possible recursive locking detected
> <4>[   13.815384] 6.3.0-rc1-CI_DRM_12814-g4753bbc2a817+ #1 Not tainted
> <4>[   13.815386] --------------------------------------------
> <4>[   13.815387] swapper/0/1 is trying to acquire lock:
> <4>[   13.815389] ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at:
> pci_enable_link_state+0x69/0x1d0
> <4>[   13.815396] 
>                   but task is already holding lock:
> <4>[   13.815398] ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at:
> pci_walk_bus+0x24/0x90
> <4>[   13.815403] 
>                   other info that might help us debug this:
> <4>[   13.815404]  Possible unsafe locking scenario:
> 
> <4>[   13.815406]        CPU0
> <4>[   13.815407]        ----
> <4>[   13.815408]   lock(pci_bus_sem);
> <4>[   13.815410]   lock(pci_bus_sem);
> <4>[   13.815411] 
>                    *** DEADLOCK ***
> 
> <4>[   13.815413]  May be due to missing lock nesting notation
> 
> <4>[   13.815414] 2 locks held by swapper/0/1:
> <4>[   13.815416]  #0: ffff8881029511b8 (&dev->mutex){....}-{3:3}, at:
> __driver_attach+0xab/0x180
> <4>[   13.815422]  #1: ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at:
> pci_walk_bus+0x24/0x90
> <4>[   13.815426] 
>                   stack backtrace:
> <4>[   13.815428] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.3.0-rc1-
> CI_DRM_12814-g4753bbc2a817+ #1
> <4>[   13.815431] Hardware name: Intel Corporation Alder Lake Client
> Platform/AlderLake-P DDR4 RVP, BIOS ADLPFWI1.R00.3135.A00.2203251419
> 03/25/2022
> <4>[   13.815434] Call Trace:
> <4>[   13.815436]  <TASK>
> <4>[   13.815437]  dump_stack_lvl+0x64/0xb0
> <4>[   13.815443]  __lock_acquire+0x9b5/0x2550
> <4>[   13.815461]  lock_acquire+0xd7/0x330
> <4>[   13.815463]  ? pci_enable_link_state+0x69/0x1d0
> <4>[   13.815466]  down_read+0x3d/0x180
> <4>[   13.815480]  ? pci_enable_link_state+0x69/0x1d0
> <4>[   13.815482]  pci_enable_link_state+0x69/0x1d0
> <4>[   13.815485]  ? __pfx_vmd_pm_enable_quirk+0x10/0x10
> <4>[   13.815488]  vmd_pm_enable_quirk+0x49/0xb0
> <4>[   13.815490]  pci_walk_bus+0x6d/0x90
> <4>[   13.815492]  vmd_probe+0x75f/0x9d0
> <4>[   13.815495]  pci_device_probe+0x95/0x120
> <4>[   13.815498]  really_probe+0x164/0x3c0
> <4>[   13.815500]  ? __pfx___driver_attach+0x10/0x10
> <4>[   13.815503]  __driver_probe_device+0x73/0x170
> <4>[   13.815506]  driver_probe_device+0x19/0xa0
> <4>[   13.815508]  __driver_attach+0xb6/0x180
> <4>[   13.815511]  ? __pfx___driver_attach+0x10/0x10
> <4>[   13.815513]  bus_for_each_dev+0x77/0xd0
> <4>[   13.815516]  bus_add_driver+0x114/0x210
> <4>[   13.815518]  driver_register+0x5b/0x110
> <4>[   13.815520]  ? __pfx_vmd_drv_init+0x10/0x10
> <4>[   13.815523]  do_one_initcall+0x57/0x330
> <4>[   13.815527]  kernel_init_freeable+0x181/0x3a0
> <4>[   13.815529]  ? __pfx_kernel_init+0x10/0x10
> <4>[   13.815532]  kernel_init+0x15/0x120
> <4>[   13.815534]  ret_from_fork+0x29/0x50
> <4>[   13.815537]  </TASK>
>
Ville Syrjälä March 21, 2023, 12:38 p.m. UTC | #3 
On Mon, Mar 20, 2023 at 07:24:16PM -0700, David E. Box wrote:
> Hi,
> 
> On Tue, 2023-03-21 at 00:56 +0200, Ville Syrjälä wrote:
> > On Thu, Jan 19, 2023 at 07:15:22PM -0800, David E. Box wrote:
> > > +/*
> > > + * Enable ASPM and LTR settings on devices that aren't configured by BIOS.
> > > + */
> > > +static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
> > > +{
> > > +       unsigned long features = *(unsigned long *)userdata;
> > > +       u16 ltr = VMD_BIOS_PM_QUIRK_LTR;
> > > +       u32 ltr_reg;
> > > +       int pos;
> > > +
> > > +       if (!(features & VMD_FEAT_BIOS_PM_QUIRK))
> > > +               return 0;
> > > +
> > > +       pci_enable_link_state(pdev, PCIE_LINK_STATE_ALL);
> 
> We call pci_enable_link_state from a callback that's run during pci_walk_bus()
> which I see already acquires the semaphore. We've had this patch for well over a
> year and I haven't seen this issue before. Is there a particular config needed
> to reproduce it?

Not sure what would affect it, beyond the normal PROVE_LOCKING=y.

This is the .config our CI uses:
https://gitlab.freedesktop.org/gfx-ci/i915-infra/-/blob/master/kconfig/debug

> 
> As far as a solution I think we can copy what __pci_disable_link_state() does
> and add a bool argument so that we only do down/up on the semaphore when set to
> true. Since we know we will in be the lock during the bus walk we can set it to
> false.
> 
> David
> 
> > 
> > Hi,
> > 
> > This is tripping lockdep on one our CI ADL machines.
> > 
> > https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_12814/bat-adlp-6/boot0.txt
> > 
> > <4>[   13.815380] ============================================
> > <4>[   13.815382] WARNING: possible recursive locking detected
> > <4>[   13.815384] 6.3.0-rc1-CI_DRM_12814-g4753bbc2a817+ #1 Not tainted
> > <4>[   13.815386] --------------------------------------------
> > <4>[   13.815387] swapper/0/1 is trying to acquire lock:
> > <4>[   13.815389] ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at:
> > pci_enable_link_state+0x69/0x1d0
> > <4>[   13.815396] 
> >                   but task is already holding lock:
> > <4>[   13.815398] ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at:
> > pci_walk_bus+0x24/0x90
> > <4>[   13.815403] 
> >                   other info that might help us debug this:
> > <4>[   13.815404]  Possible unsafe locking scenario:
> > 
> > <4>[   13.815406]        CPU0
> > <4>[   13.815407]        ----
> > <4>[   13.815408]   lock(pci_bus_sem);
> > <4>[   13.815410]   lock(pci_bus_sem);
> > <4>[   13.815411] 
> >                    *** DEADLOCK ***
> > 
> > <4>[   13.815413]  May be due to missing lock nesting notation
> > 
> > <4>[   13.815414] 2 locks held by swapper/0/1:
> > <4>[   13.815416]  #0: ffff8881029511b8 (&dev->mutex){....}-{3:3}, at:
> > __driver_attach+0xab/0x180
> > <4>[   13.815422]  #1: ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at:
> > pci_walk_bus+0x24/0x90
> > <4>[   13.815426] 
> >                   stack backtrace:
> > <4>[   13.815428] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.3.0-rc1-
> > CI_DRM_12814-g4753bbc2a817+ #1
> > <4>[   13.815431] Hardware name: Intel Corporation Alder Lake Client
> > Platform/AlderLake-P DDR4 RVP, BIOS ADLPFWI1.R00.3135.A00.2203251419
> > 03/25/2022
> > <4>[   13.815434] Call Trace:
> > <4>[   13.815436]  <TASK>
> > <4>[   13.815437]  dump_stack_lvl+0x64/0xb0
> > <4>[   13.815443]  __lock_acquire+0x9b5/0x2550
> > <4>[   13.815461]  lock_acquire+0xd7/0x330
> > <4>[   13.815463]  ? pci_enable_link_state+0x69/0x1d0
> > <4>[   13.815466]  down_read+0x3d/0x180
> > <4>[   13.815480]  ? pci_enable_link_state+0x69/0x1d0
> > <4>[   13.815482]  pci_enable_link_state+0x69/0x1d0
> > <4>[   13.815485]  ? __pfx_vmd_pm_enable_quirk+0x10/0x10
> > <4>[   13.815488]  vmd_pm_enable_quirk+0x49/0xb0
> > <4>[   13.815490]  pci_walk_bus+0x6d/0x90
> > <4>[   13.815492]  vmd_probe+0x75f/0x9d0
> > <4>[   13.815495]  pci_device_probe+0x95/0x120
> > <4>[   13.815498]  really_probe+0x164/0x3c0
> > <4>[   13.815500]  ? __pfx___driver_attach+0x10/0x10
> > <4>[   13.815503]  __driver_probe_device+0x73/0x170
> > <4>[   13.815506]  driver_probe_device+0x19/0xa0
> > <4>[   13.815508]  __driver_attach+0xb6/0x180
> > <4>[   13.815511]  ? __pfx___driver_attach+0x10/0x10
> > <4>[   13.815513]  bus_for_each_dev+0x77/0xd0
> > <4>[   13.815516]  bus_add_driver+0x114/0x210
> > <4>[   13.815518]  driver_register+0x5b/0x110
> > <4>[   13.815520]  ? __pfx_vmd_drv_init+0x10/0x10
> > <4>[   13.815523]  do_one_initcall+0x57/0x330
> > <4>[   13.815527]  kernel_init_freeable+0x181/0x3a0
> > <4>[   13.815529]  ? __pfx_kernel_init+0x10/0x10
> > <4>[   13.815532]  kernel_init+0x15/0x120
> > <4>[   13.815534]  ret_from_fork+0x29/0x50
> > <4>[   13.815537]  </TASK>
> >
David E. Box March 21, 2023, 11:40 p.m. UTC | #4 
On Tue, 2023-03-21 at 14:38 +0200, Ville Syrjälä wrote:
> On Mon, Mar 20, 2023 at 07:24:16PM -0700, David E. Box wrote:
> > Hi,
> > 
> > On Tue, 2023-03-21 at 00:56 +0200, Ville Syrjälä wrote:
> > > On Thu, Jan 19, 2023 at 07:15:22PM -0800, David E. Box wrote:
> > > > +/*
> > > > + * Enable ASPM and LTR settings on devices that aren't configured by
> > > > BIOS.
> > > > + */
> > > > +static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
> > > > +{
> > > > +       unsigned long features = *(unsigned long *)userdata;
> > > > +       u16 ltr = VMD_BIOS_PM_QUIRK_LTR;
> > > > +       u32 ltr_reg;
> > > > +       int pos;
> > > > +
> > > > +       if (!(features & VMD_FEAT_BIOS_PM_QUIRK))
> > > > +               return 0;
> > > > +
> > > > +       pci_enable_link_state(pdev, PCIE_LINK_STATE_ALL);
> > 
> > We call pci_enable_link_state from a callback that's run during
> > pci_walk_bus()
> > which I see already acquires the semaphore. We've had this patch for well
> > over a
> > year and I haven't seen this issue before. Is there a particular config
> > needed
> > to reproduce it?
> 
> Not sure what would affect it, beyond the normal PROVE_LOCKING=y.

Thanks. Did not have this set. I reproduced the issue and have sent a fix.

David

> 
> This is the .config our CI uses:
> https://gitlab.freedesktop.org/gfx-ci/i915-infra/-/blob/master/kconfig/debug
> 
> > 
> > As far as a solution I think we can copy what __pci_disable_link_state()
> > does
> > and add a bool argument so that we only do down/up on the semaphore when set
> > to
> > true. Since we know we will in be the lock during the bus walk we can set it
> > to
> > false.
> > 
> > David
> > 
> > > 
> > > Hi,
> > > 
> > > This is tripping lockdep on one our CI ADL machines.
> > > 
> > > https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_12814/bat-adlp-6/boot0.txt
> > > 
> > > <4>[   13.815380] ============================================
> > > <4>[   13.815382] WARNING: possible recursive locking detected
> > > <4>[   13.815384] 6.3.0-rc1-CI_DRM_12814-g4753bbc2a817+ #1 Not tainted
> > > <4>[   13.815386] --------------------------------------------
> > > <4>[   13.815387] swapper/0/1 is trying to acquire lock:
> > > <4>[   13.815389] ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at:
> > > pci_enable_link_state+0x69/0x1d0
> > > <4>[   13.815396] 
> > >                   but task is already holding lock:
> > > <4>[   13.815398] ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at:
> > > pci_walk_bus+0x24/0x90
> > > <4>[   13.815403] 
> > >                   other info that might help us debug this:
> > > <4>[   13.815404]  Possible unsafe locking scenario:
> > > 
> > > <4>[   13.815406]        CPU0
> > > <4>[   13.815407]        ----
> > > <4>[   13.815408]   lock(pci_bus_sem);
> > > <4>[   13.815410]   lock(pci_bus_sem);
> > > <4>[   13.815411] 
> > >                    *** DEADLOCK ***
> > > 
> > > <4>[   13.815413]  May be due to missing lock nesting notation
> > > 
> > > <4>[   13.815414] 2 locks held by swapper/0/1:
> > > <4>[   13.815416]  #0: ffff8881029511b8 (&dev->mutex){....}-{3:3}, at:
> > > __driver_attach+0xab/0x180
> > > <4>[   13.815422]  #1: ffffffff827ab0b0 (pci_bus_sem){++++}-{3:3}, at:
> > > pci_walk_bus+0x24/0x90
> > > <4>[   13.815426] 
> > >                   stack backtrace:
> > > <4>[   13.815428] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.3.0-rc1-
> > > CI_DRM_12814-g4753bbc2a817+ #1
> > > <4>[   13.815431] Hardware name: Intel Corporation Alder Lake Client
> > > Platform/AlderLake-P DDR4 RVP, BIOS ADLPFWI1.R00.3135.A00.2203251419
> > > 03/25/2022
> > > <4>[   13.815434] Call Trace:
> > > <4>[   13.815436]  <TASK>
> > > <4>[   13.815437]  dump_stack_lvl+0x64/0xb0
> > > <4>[   13.815443]  __lock_acquire+0x9b5/0x2550
> > > <4>[   13.815461]  lock_acquire+0xd7/0x330
> > > <4>[   13.815463]  ? pci_enable_link_state+0x69/0x1d0
> > > <4>[   13.815466]  down_read+0x3d/0x180
> > > <4>[   13.815480]  ? pci_enable_link_state+0x69/0x1d0
> > > <4>[   13.815482]  pci_enable_link_state+0x69/0x1d0
> > > <4>[   13.815485]  ? __pfx_vmd_pm_enable_quirk+0x10/0x10
> > > <4>[   13.815488]  vmd_pm_enable_quirk+0x49/0xb0
> > > <4>[   13.815490]  pci_walk_bus+0x6d/0x90
> > > <4>[   13.815492]  vmd_probe+0x75f/0x9d0
> > > <4>[   13.815495]  pci_device_probe+0x95/0x120
> > > <4>[   13.815498]  really_probe+0x164/0x3c0
> > > <4>[   13.815500]  ? __pfx___driver_attach+0x10/0x10
> > > <4>[   13.815503]  __driver_probe_device+0x73/0x170
> > > <4>[   13.815506]  driver_probe_device+0x19/0xa0
> > > <4>[   13.815508]  __driver_attach+0xb6/0x180
> > > <4>[   13.815511]  ? __pfx___driver_attach+0x10/0x10
> > > <4>[   13.815513]  bus_for_each_dev+0x77/0xd0
> > > <4>[   13.815516]  bus_add_driver+0x114/0x210
> > > <4>[   13.815518]  driver_register+0x5b/0x110
> > > <4>[   13.815520]  ? __pfx_vmd_drv_init+0x10/0x10
> > > <4>[   13.815523]  do_one_initcall+0x57/0x330
> > > <4>[   13.815527]  kernel_init_freeable+0x181/0x3a0
> > > <4>[   13.815529]  ? __pfx_kernel_init+0x10/0x10
> > > <4>[   13.815532]  kernel_init+0x15/0x120
> > > <4>[   13.815534]  ret_from_fork+0x29/0x50
> > > <4>[   13.815537]  </TASK>
> > > 
>
diff mbox series

Patch

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 47fa3e5f2dc5..990630ec57c6 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -66,11 +66,22 @@  enum vmd_features {
 	 * interrupt handling.
 	 */
 	VMD_FEAT_CAN_BYPASS_MSI_REMAP		= (1 << 4),
+
+	/*
+	 * Enable ASPM on the PCIE root ports and set the default LTR of the
+	 * storage devices on platforms where these values are not configured by
+	 * BIOS. This is needed for laptops, which require these settings for
+	 * proper power management of the SoC.
+	 */
+	VMD_FEAT_BIOS_PM_QUIRK		= (1 << 5),
 };
 
+#define VMD_BIOS_PM_QUIRK_LTR	0x1003	/* 3145728 ns */
+
 #define VMD_FEATS_CLIENT	(VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP |	\
 				 VMD_FEAT_HAS_BUS_RESTRICTIONS |	\
-				 VMD_FEAT_OFFSET_FIRST_VECTOR)
+				 VMD_FEAT_OFFSET_FIRST_VECTOR |		\
+				 VMD_FEAT_BIOS_PM_QUIRK)
 
 static DEFINE_IDA(vmd_instance_ida);
 
@@ -713,6 +724,46 @@  static void vmd_copy_host_bridge_flags(struct pci_host_bridge *root_bridge,
 	vmd_bridge->native_dpc = root_bridge->native_dpc;
 }
 
+/*
+ * Enable ASPM and LTR settings on devices that aren't configured by BIOS.
+ */
+static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
+{
+	unsigned long features = *(unsigned long *)userdata;
+	u16 ltr = VMD_BIOS_PM_QUIRK_LTR;
+	u32 ltr_reg;
+	int pos;
+
+	if (!(features & VMD_FEAT_BIOS_PM_QUIRK))
+		return 0;
+
+	pci_enable_link_state(pdev, PCIE_LINK_STATE_ALL);
+
+	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_LTR);
+	if (!pos)
+		return 0;
+
+	/*
+	 * Skip if the max snoop LTR is non-zero, indicating BIOS has set it
+	 * so the LTR quirk is not needed.
+	 */
+	pci_read_config_dword(pdev, pos + PCI_LTR_MAX_SNOOP_LAT, &ltr_reg);
+	if (!!(ltr_reg & (PCI_LTR_VALUE_MASK | PCI_LTR_SCALE_MASK)))
+		return 0;
+
+	/*
+	 * Set the default values to the maximum required by the platform to
+	 * allow the deepest power management savings. Write as a DWORD where
+	 * the lower word is the max snoop latency and the upper word is the
+	 * max non-snoop latency.
+	 */
+	ltr_reg = (ltr << 16) | ltr;
+	pci_write_config_dword(pdev, pos + PCI_LTR_MAX_SNOOP_LAT, ltr_reg);
+	pci_info(pdev, "VMD: Default LTR value set by driver\n");
+
+	return 0;
+}
+
 static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 {
 	struct pci_sysdata *sd = &vmd->sysdata;
@@ -885,6 +936,8 @@  static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 
 	pci_assign_unassigned_bus_resources(vmd->bus);
 
+	pci_walk_bus(vmd->bus, vmd_pm_enable_quirk, &features);
+
 	/*
 	 * VMD root buses are virtual and don't return true on pci_is_pcie()
 	 * and will fail pcie_bus_configure_settings() early. It can instead be