Date:   Wed, 20 Apr 2022 15:56:56 -0500
From:   "Gong, Richard" <richard.gong@....com>
To:     Paul Menzel <pmenzel@...gen.mpg.de>,
        Alex Deucher <alexdeucher@...il.com>
Cc:     Dave Airlie <airlied@...ux.ie>, Xinhui Pan <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>,
        Alexander Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCHv4] drm/amdgpu: disable ASPM on Intel Alder Lake based
 systems

Hi Paul,

On 4/20/2022 3:48 PM, Paul Menzel wrote:
> Dear Alex,
>
>
> Am 20.04.22 um 22:40 schrieb Alex Deucher:
>> On Wed, Apr 20, 2022 at 4:29 PM Paul Menzel <pmenzel@...gen.mpg.de> 
>> wrote:
>
>>> Am 19.04.22 um 23:46 schrieb Gong, Richard:
>>>
>>>> On 4/14/2022 2:52 AM, Paul Menzel wrote:
>>>>> [Cc: -kernel test robot <lkp@...el.com>]
>>>
>>> […]
>>>
>>>>> 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.
>>>
>>> [Your email program wraps lines in cited text for some reason, making
>>> the citation harder to read.]
>>>
>>>>>>>
>>>>>>> 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?
>>>> System freeze after suspend/resume.
>>>
>>> But you see certain messages still? At what point does it freeze
>>> exactly? In the bug report you posted Linux messages.
>>>
>>>>>>>> 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%2Fgitlab.freedesktop.org%2Fdrm%2Famd%2F-%2Fissues%2F1885&amp;data=05%7C01%7Crichard.gong%40amd.com%7C487aaa63098b462e146a08da230f2319%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637860845178176835%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=3IVldn05qNa2XVp1Lu58SriS8k9mk4U9K9p3F3IYPe0%3D&amp;reserved=0 
>>>>>>>>
>>>
>>> Thank you Microsoft Outlook for keeping us safe. :(
>>>
>>>>>>>>
>>>>>>>> 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?
>>>>
>>>> I did describe in change-list version 3 below, which corrected the 
>>>> build
>>>> error with W=1 option.
>>>>
>>>> It is not good idea to add the description for that to the commit
>>>> message, this is why I add descriptions on change-list version 3.
>>>
>>> Do as you wish, but the current style is confusing, and readers of the
>>> commit are going to think, the kernel test robot reported the problem
>>> with AMD VI ASICs and Intel Alder Lake systems.
>>>
>>>>>>>
>>>>>>>> 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);
>>>>>>>> +     }
>>>>>>>> +
>>>>>>>> +     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`?
>>>>>>>
>>>> As Mario mentioned in a separate reply, we can't forcefully enable 
>>>> ASPM
>>>> with the parameter 'amdgpu.aspm'.
>>>
>>> That would be a regression on systems where ASPM used to work. Hmm. I
>>> guess, you could say, there are no such systems.
>>>
>>>>>>>>
>>>>>>>>         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 generatioaon that was 
>>>>>> problematic.
>>>>>
>>>>> Could that please be made clear in the commit message summary, and
>>>>> message?
>>>>
>>>> Are you ok with the commit messages below?
>>>
>>> Please change the commit message summary. Maybe:
>>>
>>> drm/amdgpu: VI: Disable ASPM on Intel Alder Lake based systems
>>>
>>>> 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 freeze after
>>>> suspend/resume.
>>>
>>> Something like:
>>>
>>> On Intel Alder Lake based systems using ASPM with AMD GFX Volcanic
>>> Islands (VI) cards, like WX3200 and RX640, graphics don’t initialize
>>> when resuming from S0ix(?).
>>>
>>>
>>>> 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.
>>>
>>> Which ones?
>>>
>>>> Add extra check to disable ASPM on Intel Alder Lake based systems with
>>>> problematic generation GFX cards.
>>>
>>> … with the problematic Volcanic Islands GFX cards.
>>>
>>>>>
>>>>> Loosely related, is there a public (or internal issue) to analyze how
>>>>> to get ASPM working for VI generation devices with Intel Alder Lake?
>>>>
>>>> As Alex mentioned, we need support from Intel. We don't have any 
>>>> update
>>>> on that.
>>>
>>> It’d be great to get that fixed properly.
>>>
>>> Last thing, please don’t hate me, does Linux log, that ASPM is 
>>> disabled?
>>
>> I'm not sure what gets logged at the platform level with respect to
>> ASPM, but whether or not the driver enables ASPM is tied to whether
>> ASPM is allowed at the platform level or not so if the platform
>> indicates that ASPM is not supported, the driver won't enable it.  The
>> driver does not log whether ASPM is enabled or not if that is what you
>> are asking.  As to whether or not it should, it comes down to how much
>> stuff is worth indiciating in the log.  The driver is already pretty
>> chatty by driver standards.
>
> I specifically mean, Linux should log the quirks it applies. (As a 
> normal user, I’d also expect ASPM to work nowadays, so a message, that 
> it’s disabled would help a lot.)

In general rule we shouldn't generate additional log unless something 
went wrong with the system.

>
>
> Kind regards,
>
> Paul

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