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

[Paul Menzel]

[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?

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


Kind regards,

Paul