Re: [PATCHv4] drm/amdgpu: disable ASPM on Intel Alder Lake based systems

[Alex Deucher]

On Thu, Apr 14, 2022 at 3:52 AM Paul Menzel <pmenzel@xxxxxxxxxxxxx> wrote:
>
> [Cc: -kernel test robot <lkp@xxxxxxxxx>]
>
> Dear Alex, dear Richard,
>
>
> Am 13.04.22 um 15:00 schrieb Alex Deucher:
> > On Wed, Apr 13, 2022 at 3:43 AM Paul Menzel wrote:
>
> >> Thank you for sending out v4.
> >>
> >> Am 12.04.22 um 23:50 schrieb Richard Gong:
> >>> Active State Power Management (ASPM) feature is enabled since kernel 5.14.
> >>> There are some AMD GFX cards (such as WX3200 and RX640) that won't work
> >>> with ASPM-enabled Intel Alder Lake based systems. Using these GFX cards as
> >>> video/display output, Intel Alder Lake based systems will hang during
> >>> suspend/resume.
> >>
> >> I am still not clear, what “hang during suspend/resume” means. I guess
> >> suspending works fine? During resume (S3 or S0ix?), where does it hang?
> >> The system is functional, but there are only display problems?
> >>
> >>> The issue was initially reported on one system (Dell Precision 3660 with
> >>> BIOS version 0.14.81), but was later confirmed to affect at least 4 Alder
> >>> Lake based systems.
> >>>
> >>> Add extra check to disable ASPM on Intel Alder Lake based systems.
> >>>
> >>> Fixes: 0064b0ce85bb ("drm/amd/pm: enable ASPM by default")
> >>> Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1885
> >>> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> >>
> >> This tag is a little confusing. Maybe clarify that it was for an issue
> >> in a previous patch iteration?
> >>
> >>> Signed-off-by: Richard Gong <richard.gong@xxxxxxx>
> >>> ---
> >>> v4: s/CONFIG_X86_64/CONFIG_X86
> >>>       enhanced check logic
> >>> v3: s/intel_core_asom_chk/aspm_support_quirk_check
> >>>       correct build error with W=1 option
> >>> v2: correct commit description
> >>>       move the check from chip family to problematic platform
> >>> ---
> >>>    drivers/gpu/drm/amd/amdgpu/vi.c | 17 ++++++++++++++++-
> >>>    1 file changed, 16 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/amd/amdgpu/vi.c b/drivers/gpu/drm/amd/amdgpu/vi.c
> >>> index 039b90cdc3bc..b33e0a9bee65 100644
> >>> --- a/drivers/gpu/drm/amd/amdgpu/vi.c
> >>> +++ b/drivers/gpu/drm/amd/amdgpu/vi.c
> >>> @@ -81,6 +81,10 @@
> >>>    #include "mxgpu_vi.h"
> >>>    #include "amdgpu_dm.h"
> >>>
> >>> +#if IS_ENABLED(CONFIG_X86)
> >>> +#include <asm/intel-family.h>
> >>> +#endif
> >>> +
> >>>    #define ixPCIE_LC_L1_PM_SUBSTATE    0x100100C6
> >>>    #define PCIE_LC_L1_PM_SUBSTATE__LC_L1_SUBSTATES_OVERRIDE_EN_MASK    0x00000001L
> >>>    #define PCIE_LC_L1_PM_SUBSTATE__LC_PCI_PM_L1_2_OVERRIDE_MASK        0x00000002L
> >>> @@ -1134,13 +1138,24 @@ static void vi_enable_aspm(struct amdgpu_device *adev)
> >>>                WREG32_PCIE(ixPCIE_LC_CNTL, data);
> >>>    }
> >>>
> >>> +static bool aspm_support_quirk_check(void)
> >>> +{
> >>> +     if (IS_ENABLED(CONFIG_X86)) {
> >>> +             struct cpuinfo_x86 *c = &cpu_data(0);
> >>> +
> >>> +             return !(c->x86 == 6 && c->x86_model == INTEL_FAM6_ALDERLAKE);
> >>> +     }
> >>> +
> >>> +     return true;
> >>> +}
> >>> +
> >>>    static void vi_program_aspm(struct amdgpu_device *adev)
> >>>    {
> >>>        u32 data, data1, orig;
> >>>        bool bL1SS = false;
> >>>        bool bClkReqSupport = true;
> >>>
> >>> -     if (!amdgpu_device_should_use_aspm(adev))
> >>> +     if (!amdgpu_device_should_use_aspm(adev) || !aspm_support_quirk_check())
> >>>                return;
> >>
> >> Can users still forcefully enable ASPM with the parameter `amdgpu.aspm`?
> >>
> >>>
> >>>        if (adev->flags & AMD_IS_APU ||
> >>
> >> If I remember correctly, there were also newer cards, where ASPM worked
> >> with Intel Alder Lake, right? Can only the problematic generations for
> >> WX3200 and RX640 be excluded from ASPM?
> >
> > This patch only disables it for the generation that was problematic.
>
> Could that please be made clear in the commit message summary, and message?

Sure.  Richard, please add that this only disables ASPM on VI parts
when in an alderlake system.

>
> Loosely related, is there a public (or internal issue) to analyze how to
> get ASPM working for VI generation devices with Intel Alder Lake?

We'd need support from Intel.  I'm not sure where things currently stand.

Alex