linux-kernel - RE: [PATCHv4] drm/amdgpu: disable ASPM on Intel Alder Lake based systems

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Message-ID: <BL1PR12MB515779F96AF6727B238BB32FE2EC9@BL1PR12MB5157.namprd12.prod.outlook.com>
Date:   Wed, 13 Apr 2022 13:28:28 +0000
From:   "Limonciello, Mario" <Mario.Limonciello@....com>
To:     Alex Deucher <alexdeucher@...il.com>,
        Paul Menzel <pmenzel@...gen.mpg.de>
CC:     "Gong, Richard" <Richard.Gong@....com>,
        kernel test robot <lkp@...el.com>,
        Dave Airlie <airlied@...ux.ie>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>, Daniel Vetter <daniel@...ll.ch>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Koenig, Christian" <Christian.Koenig@....com>
Subject: RE: [PATCHv4] drm/amdgpu: disable ASPM on Intel Alder Lake based
 systems

[Public]

 
> On Wed, Apr 13, 2022 at 3:43 AM Paul Menzel <pmenzel@...gen.mpg.de>
> wrote:
> >
> > Dear Richard,
> >
> >
> > 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?

I believe Intel would need to identify the state of the SOC to determine where
the PCIE problem actually occurs; on the way down or up.

As he said in the commit message it results in a hang.

> >
> > > 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://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitla
> b.freedesktop.org%2Fdrm%2Famd%2F-
> %2Fissues%2F1885&amp;data=04%7C01%7Cmario.limonciello%40amd.com%
> 7Cfe4b6b553c3b47c1288f08da1d4da9c8%7C3dd8961fe4884e608e11a82d994e
> 183d%7C0%7C0%7C637854516675116782%7CUnknown%7CTWFpbGZsb3d8ey
> JWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%
> 7C3000&amp;sdata=gvFmP1HQP%2FyzLfT0gYYCupAQBIG%2FtiDYelQNqTLAx
> ck%3D&amp;reserved=0
> > > Reported-by: kernel test robot <lkp@...el.com>
> >
> > 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@....com>
> > > ---
> > > 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);

Don't you need to check x86_vendor?  Although extremely unlikely if you don't
check x86_vendor nothing to stop another X86 manufacturer from having a
design that has same model # as 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`?

amdgpu.aspm is module wide not just for one card.  That is it covers all AMD GPU cards
in the system.  If it's set to 1 or pcie_aspm_enabled returns true it will enable for other
GPUs besides these.

There is the possibility to move this quirk check within " amdgpu_device_should_use_aspm"
and only match this combination when set to amdgpu.aspm is set to "-1" (the default), something
like this:

--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -1335,6 +1335,8 @@ bool amdgpu_device_should_use_aspm(struct amdgpu_device *adev)
        default:
                return false;
        }
+       if (amdgpu_device_is_quirked_for_aspm(adev))
+               return false;
        return pcie_aspm_enabled(adev->pdev);
 }


> >
> > >
> > >       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.
> 
> Alex
> 
> >
> >
> > Kind regards,
> >
> > Paul