Re: [PATCH] drm/amdgpu: move PDB bo release into a generic gmc function

[Christian König <christian.koenig@xxxxxxx>]

Mhm, actually that is indeed purely gmc 9 specific.

This is a workaround for a very specific hardware bug issue which will 
hopefully never happen again :)

We just implemented it in the common handler to be able to test it with 
gmc 8 before gmc 9 came out of production.

Do we have a generic amdgpu_gmc_sw_finit()? If yes I would put it there 
instead, if no we might want to create one.

Regards,
Christian.

Am 17.03.22 um 13:50 schrieb Chen, Guchun:
> Hi Christian,
>
> My intention is to use a paired generic gmc alloc/free function to proceed PDB bo. Current code is gmc v9 code calls amdgpu_gmc_pdb0_alloc to allocate PDB bo buffer, and release the bo directly in gmc_v9_0_sw_fini. I guess PDB bo is not a gmc v9 specific buffer, so it's better to use a release function from amdgpu_gem.c in fini. This may benefit the case that users do the same in GMC newer IP code.
>
> Regards,
> Guchun
>
> -----Original Message-----
> From: Christian König <ckoenig.leichtzumerken@xxxxxxxxx>
> Sent: Thursday, March 17, 2022 8:14 PM
> To: Chen, Guchun <Guchun.Chen@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Zhang, Hawking <Hawking.Zhang@xxxxxxx>; Koenig, Christian <Christian.Koenig@xxxxxxx>; Pan, Xinhui <Xinhui.Pan@xxxxxxx>; Deucher, Alexander <Alexander.Deucher@xxxxxxx>
> Subject: Re: [PATCH] drm/amdgpu: move PDB bo release into a generic gmc function
>
> Am 17.03.22 um 12:21 schrieb Guchun Chen:
> > To pair with amdgpu_gmc_pdb0_alloc as a more generic handling in
> > amdgpu_gmc.c, no functional change.
> >
> > Signed-off-by: Guchun Chen <guchun.chen@xxxxxxx>
> > ---
> >    drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 6 ++++++
> >    drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h | 1 +
> >    drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c   | 2 +-
> >    3 files changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> > index 7021e8f390bd..36f6b321438f 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> > @@ -136,6 +136,12 @@ uint64_t amdgpu_gmc_pd_addr(struct amdgpu_bo *bo)
> >    	return pd_addr;
> >    }
> >    
> > +/* amdgpu_gmc_pdb0_free - free pdb0 vram */ void
> > +amdgpu_gmc_pdb0_free(struct amdgpu_device *adev) {
> > +	amdgpu_bo_free_kernel(&adev->gmc.pdb0_bo, NULL,
> > +&adev->gmc.ptr_pdb0); }
> > +
> Single line function usually doesn't look that useful to me.
>
> Why is that any improvement?
>
> Regards,
> Christian.
>
> >    /**
> >     * amdgpu_gmc_set_pte_pde - update the page tables using CPU
> >     *
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> > index 032b0313f277..6f425e3a9b6e 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> > @@ -299,6 +299,7 @@ static inline uint64_t amdgpu_gmc_sign_extend(uint64_t addr)
> >    }
> >    
> >    int amdgpu_gmc_pdb0_alloc(struct amdgpu_device *adev);
> > +void amdgpu_gmc_pdb0_free(struct amdgpu_device *adev);
> >    void amdgpu_gmc_get_pde_for_bo(struct amdgpu_bo *bo, int level,
> >    			       uint64_t *addr, uint64_t *flags);
> >    int amdgpu_gmc_set_pte_pde(struct amdgpu_device *adev, void *cpu_pt_addr,
> > diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> > index 08ceabd6c853..ad600f72a51c 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> > @@ -1721,7 +1721,7 @@ static int gmc_v9_0_sw_fini(void *handle)
> >    	amdgpu_gem_force_release(adev);
> >    	amdgpu_vm_manager_fini(adev);
> >    	amdgpu_gart_table_vram_free(adev);
> > -	amdgpu_bo_free_kernel(&adev->gmc.pdb0_bo, NULL, &adev->gmc.ptr_pdb0);
> > +	amdgpu_gmc_pdb0_free(adev);
> >    	amdgpu_bo_fini(adev);
> >    
> >    	return 0;