[PATCH] drm/amdgpu: fix modprobe failure of the 2nd GPU when GDDR6 training enabled

Christian König ckoenig.leichtzumerken at gmail.com
Thu Jan 9 10:29:50 UTC 2020 

Hi Rico,

maybe it is a good idea to look into the git history and/or google the 
mailing list history a bit more.

I do briefly remember that we disabled freeing up the stolen VGA memory 
on some hardware generations because somebody was accessing that memory 
even after VGA was turned off.

At that time we couldn't figure out what was going wrong, but it is 
perfectly possible that those memory training fixes your are working on 
here are related to that issue.

On the other hand if you can't find anything immediately feel free to go 
with Alex suggestion, if something goes wrong we can still revert the 
change.

Regards,
Christian.

Am 09.01.20 um 04:15 schrieb Yin, Tianci (Rico):
>
> [AMD Official Use Only - Internal Distribution Only]
>
>
> Ok, thanks very much Alex!
> ------------------------------------------------------------------------
> *From:* Alex Deucher <alexdeucher at gmail.com>
> *Sent:* Thursday, January 9, 2020 11:12
> *To:* Yin, Tianci (Rico) <Tianci.Yin at amd.com>
> *Cc:* Christian König <ckoenig.leichtzumerken at gmail.com>; Koenig, 
> Christian <Christian.Koenig at amd.com>; Long, Gang <Gang.Long at amd.com>; 
> Wang, Kevin(Yang) <Kevin1.Wang at amd.com>; Xu, Feifei 
> <Feifei.Xu at amd.com>; amd-gfx list <amd-gfx at lists.freedesktop.org>; 
> Tuikov, Luben <Luben.Tuikov at amd.com>; Deucher, Alexander 
> <Alexander.Deucher at amd.com>; Yuan, Xiaojie <Xiaojie.Yuan at amd.com>; 
> Zhang, Hawking <Hawking.Zhang at amd.com>
> *Subject:* Re: [PATCH] drm/amdgpu: fix modprobe failure of the 2nd GPU 
> when GDDR6 training enabled
> On Wed, Jan 8, 2020 at 10:07 PM Yin, Tianci (Rico) 
> <Tianci.Yin at amd.com> wrote:
> >
> > [AMD Official Use Only - Internal Distribution Only]
> >
> >
> > Thanks Alex and Christian!
> >
> > Hi Christian,
> >
> > On ASICs with gmc v10, I find amdgpu_bo_late_init() is not invoked, 
> so stolen memory never get free, on other ASICs with gmc v9/v8/v7/v6, 
> stolen memory was freed in gmc_v*_0_late_init(). I don't know why, are 
> there some special reasons or just missed by coding?
> >
>
> Looks like it should be added.  Possibly got lost when we merged the
> navi code from the topic branch.
>
> Alex
>
> > Thanks!
> >
> > Rico
> >
> > ________________________________
> > From: Christian König <ckoenig.leichtzumerken at gmail.com>
> > Sent: Wednesday, January 8, 2020 23:04
> > To: Alex Deucher <alexdeucher at gmail.com>; Koenig, Christian 
> <Christian.Koenig at amd.com>
> > Cc: Long, Gang <Gang.Long at amd.com>; Wang, Kevin(Yang) 
> <Kevin1.Wang at amd.com>; Xu, Feifei <Feifei.Xu at amd.com>; Yin, Tianci 
> (Rico) <Tianci.Yin at amd.com>; amd-gfx list 
> <amd-gfx at lists.freedesktop.org>; Tuikov, Luben <Luben.Tuikov at amd.com>; 
> Deucher, Alexander <Alexander.Deucher at amd.com>; Yuan, Xiaojie 
> <Xiaojie.Yuan at amd.com>; Zhang, Hawking <Hawking.Zhang at amd.com>
> > Subject: Re: [PATCH] drm/amdgpu: fix modprobe failure of the 2nd GPU 
> when GDDR6 training enabled
> >
> > Am 08.01.20 um 15:49 schrieb Alex Deucher:
> > > On Wed, Jan 8, 2020 at 7:52 AM Christian König 
> <christian.koenig at amd.com> wrote:
> > >> Am 08.01.20 um 13:36 schrieb Tianci Yin:
> > >>> From: "Tianci.Yin" <tianci.yin at amd.com>
> > >>>
> > >>> [why]
> > >>> In dual GPUs scenario, stolen_size is assigned to zero on the 
> 2nd GPU,
> > >>> then the bottom region of VRAM was allocated as GTT, unfortunately
> > >>> a small region of bottom VRAM was encroached by UMC firmware during
> > >>> GDDR6 BIST training, this cause pagefault.
> > >> What I'm missing here is why is the stolen size zero on the 2nd GPU?
> > >>
> > >> Maybe we need to read the stolen size after posting the GPU instead?
> > > There is no stolen memory on secondary GPUs because there is no pre-OS
> > > console using that memory.
> >
> > Ah! Yeah that makes sense.
> >
> > But in this case I would say we should change the patch like the 
> following:
> >
> > adev->gmc.stolen_size = min(adev->gmc.stolen_size,
> > AMDGPU_STOLEN_VGA_DEFAULT_SIZE);
> >
> > And in amdgpu_ttm_late_init():
> >
> > /* Can't free the stolen VGA memory when it might be used for memory
> > training again. */
> > if (!adev->fw_vram_usage.mem_train_support)
> >      amdgpu_bo_free_kernel(....
> >
> >
> > Regards,
> > Christian.
> >
> >
> > >
> > > Alex
> > >
> > >> Regards,
> > >> Christian.
> > >>
> > >>> [how]
> > >>> Forcing stolen_size to 3MB, then the bottom region of VRAM was
> > >>> allocated as stolen memory, GTT corruption avoid.
> > >>> The stolen memory of the 2nd GPU will be free in late_init phase,
> > >>> no memory wasted.
> > >>>
> > >>> Change-Id: Icd0ad7de41333282949bb1e3e676c6c307ddd081
> > >>> Signed-off-by: Tianci.Yin <tianci.yin at amd.com>
> > >>> ---
> > >>> drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h |  6 ++++++
> > >>> drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c  | 21 +++++++++++++++++++++
> > >>>    2 files changed, 27 insertions(+)
> > >>>
> > >>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> > >>> index c91dd602d5f1..440b793316df 100644
> > >>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> > >>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> > >>> @@ -60,6 +60,11 @@
> > >>>     */
> > >>>    #define AMDGPU_GMC_FAULT_TIMEOUT 5000ULL
> > >>>
> > >>> +/*
> > >>> + * Default stolen memory size, 1024 * 768 * 4
> > >>> + */
> > >>> +#define AMDGPU_STOLEN_VGA_DEFAULT_SIZE       0x300000
> > >>> +
> > >>>    struct firmware;
> > >>>
> > >>>    /*
> > >>> @@ -192,6 +197,7 @@ struct amdgpu_gmc {
> > >>>        uint32_t srbm_soft_reset;
> > >>>        bool prt_warning;
> > >>>        uint64_t stolen_size;
> > >>> +     bool stolen_temp_reserved;
> > >>>        /* apertures */
> > >>>        u64 shared_aperture_start;
> > >>>        u64 shared_aperture_end;
> > >>> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c 
> b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> > >>> index 7dc8c068c62a..0c96b67d6ca7 100644
> > >>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> > >>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> > >>> @@ -566,6 +566,11 @@ static int gmc_v10_0_late_init(void *handle)
> > >>>        struct amdgpu_device *adev = (struct amdgpu_device *)handle;
> > >>>        int r;
> > >>>
> > >>> +     if (adev->gmc.stolen_temp_reserved) {
> > >>> + amdgpu_bo_late_init(adev);
> > >>> + adev->gmc.stolen_temp_reserved = false;
> > >>> +     }
> > >>> +
> > >>>        r = amdgpu_gmc_allocate_vm_inv_eng(adev);
> > >>>        if (r)
> > >>>                return r;
> > >>> @@ -756,6 +761,22 @@ static int gmc_v10_0_sw_init(void *handle)
> > >>>                return r;
> > >>>
> > >>>        adev->gmc.stolen_size = gmc_v10_0_get_vbios_fb_size(adev);
> > >>> +     /*
> > >>> +      * In dual GPUs scenario, stolen_size is assigned to zero 
> on the 2nd GPU,
> > >>> +      * then the bottom region of VRAM was allocated as GTT, 
> unfortunately
> > >>> +      * a small region of bottom VRAM was encroached by UMC 
> firmware during
> > >>> +      * GDDR6 BIST training, this cause pagefault.
> > >>> +      * The page fault can be fixed by forcing stolen_size to 
> 3MB, then the bottom
> > >>> +      * region of VRAM was allocated as stolen memory, GTT 
> corruption avoid.
> > >>> +      * The stolen memory of the 2nd GPU will be free in 
> late_init phase,
> > >>> +      * no memory wasted.
> > >>> +      */
> > >>> +     if (adev->fw_vram_usage.mem_train_support &&
> > >>> +             adev->gmc.stolen_size == 0) {
> > >>> +             adev->gmc.stolen_size = 
> AMDGPU_STOLEN_VGA_DEFAULT_SIZE;
> > >>> + adev->gmc.stolen_temp_reserved = true;
> > >>> +     } else
> > >>> + adev->gmc.stolen_temp_reserved = false;
> > >>>
> > >>>        /* Memory manager */
> > >>>        r = amdgpu_bo_init(adev);
> > >> _______________________________________________
> > >> amd-gfx mailing list
> > >> amd-gfx at lists.freedesktop.org
> > >> 
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> > > _______________________________________________
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