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

[Paul Menzel <pmenzel@molgen.mpg.de>]

[Cc: -kernel test robot <lkp@intel.com>]

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@intel.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@amd.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);
>>> +     }
>>> +
>>> +     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