[PATCH 7/8] drm/etnaviv: reference MMU context when setting up hardware state

[Lucas Stach]

Am Dienstag, dem 24.08.2021 um 09:24 +0200 schrieb Christian Gmeiner:
> Am Fr., 20. Aug. 2021 um 22:18 Uhr schrieb Lucas Stach <l.stach at pengutronix.de>:
> > 
> > Move the refcount manipulation of the MMU context to the point where the
> > hardware state is programmed. At that point it is also known if a previous
> > MMU state is still there, or the state needs to be reprogrammed with a
> > potentially different context.
> > 
> > Cc: stable at vger.kernel.org # 5.4
> > Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
> > Tested-by: Michael Walle <michael at walle.cc>
> > ---
> >  drivers/gpu/drm/etnaviv/etnaviv_gpu.c      | 24 +++++++++++-----------
> >  drivers/gpu/drm/etnaviv/etnaviv_iommu.c    |  4 ++++
> >  drivers/gpu/drm/etnaviv/etnaviv_iommu_v2.c |  8 ++++++++
> >  3 files changed, 24 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> > index f420c4f14657..1fa98ce870f7 100644
> > --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> > @@ -641,17 +641,19 @@ void etnaviv_gpu_start_fe(struct etnaviv_gpu *gpu, u32 address, u16 prefetch)
> >         gpu->fe_running = true;
> >  }
> > 
> > -static void etnaviv_gpu_start_fe_idleloop(struct etnaviv_gpu *gpu)
> > +static void etnaviv_gpu_start_fe_idleloop(struct etnaviv_gpu *gpu,
> > +                                         struct etnaviv_iommu_context *context)
> >  {
> > -       u32 address = etnaviv_cmdbuf_get_va(&gpu->buffer,
> > -                               &gpu->mmu_context->cmdbuf_mapping);
> >         u16 prefetch;
> > +       u32 address;
> > 
> >         /* setup the MMU */
> > -       etnaviv_iommu_restore(gpu, gpu->mmu_context);
> > +       etnaviv_iommu_restore(gpu, context);
> > 
> >         /* Start command processor */
> >         prefetch = etnaviv_buffer_init(gpu);
> > +       address = etnaviv_cmdbuf_get_va(&gpu->buffer,
> > +                                       &gpu->mmu_context->cmdbuf_mapping);
> > 
> >         etnaviv_gpu_start_fe(gpu, address, prefetch);
> >  }
> > @@ -1369,14 +1371,12 @@ struct dma_fence *etnaviv_gpu_submit(struct etnaviv_gem_submit *submit)
> >                 goto out_unlock;
> >         }
> > 
> > -       if (!gpu->fe_running) {
> > -               gpu->mmu_context = etnaviv_iommu_context_get(submit->mmu_context);
> > -               etnaviv_gpu_start_fe_idleloop(gpu);
> > -       } else {
> > -               if (submit->prev_mmu_context)
> > -                       etnaviv_iommu_context_put(submit->prev_mmu_context);
> > -               submit->prev_mmu_context = etnaviv_iommu_context_get(gpu->mmu_context);
> > -       }
> > +       if (!gpu->fe_running)
> > +               etnaviv_gpu_start_fe_idleloop(gpu, submit->mmu_context);
> > +
> > +       if (submit->prev_mmu_context)
> > +               etnaviv_iommu_context_put(submit->prev_mmu_context);
> > +       submit->prev_mmu_context = etnaviv_iommu_context_get(gpu->mmu_context);
> > 
> >         if (submit->nr_pmrs) {
> >                 gpu->event[event[1]].sync_point = &sync_point_perfmon_sample_pre;
> > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_iommu.c b/drivers/gpu/drm/etnaviv/etnaviv_iommu.c
> > index 1a7c89a67bea..afe5dd6a9925 100644
> > --- a/drivers/gpu/drm/etnaviv/etnaviv_iommu.c
> > +++ b/drivers/gpu/drm/etnaviv/etnaviv_iommu.c
> > @@ -92,6 +92,10 @@ static void etnaviv_iommuv1_restore(struct etnaviv_gpu *gpu,
> >         struct etnaviv_iommuv1_context *v1_context = to_v1_context(context);
> >         u32 pgtable;
> > 
> > +       if (gpu->mmu_context)
> > +               etnaviv_iommu_context_put(gpu->mmu_context);
> > +       gpu->mmu_context = etnaviv_iommu_context_get(context);
> > +
> >         /* set base addresses */
> >         gpu_write(gpu, VIVS_MC_MEMORY_BASE_ADDR_RA, context->global->memory_base);
> >         gpu_write(gpu, VIVS_MC_MEMORY_BASE_ADDR_FE, context->global->memory_base);
> > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_iommu_v2.c b/drivers/gpu/drm/etnaviv/etnaviv_iommu_v2.c
> > index f8bf488e9d71..d664ae29ae20 100644
> > --- a/drivers/gpu/drm/etnaviv/etnaviv_iommu_v2.c
> > +++ b/drivers/gpu/drm/etnaviv/etnaviv_iommu_v2.c
> > @@ -172,6 +172,10 @@ static void etnaviv_iommuv2_restore_nonsec(struct etnaviv_gpu *gpu,
> >         if (gpu_read(gpu, VIVS_MMUv2_CONTROL) & VIVS_MMUv2_CONTROL_ENABLE)
> >                 return;
> > 
> > +       if (gpu->mmu_context)
> > +               etnaviv_iommu_context_put(gpu->mmu_context);
> > +       gpu->mmu_context = etnaviv_iommu_context_get(context);
> > +
> >         prefetch = etnaviv_buffer_config_mmuv2(gpu,
> >                                 (u32)v2_context->mtlb_dma,
> >                                 (u32)context->global->bad_page_dma);
> > @@ -192,6 +196,10 @@ static void etnaviv_iommuv2_restore_sec(struct etnaviv_gpu *gpu,
> >         if (gpu_read(gpu, VIVS_MMUv2_SEC_CONTROL) & VIVS_MMUv2_SEC_CONTROL_ENABLE)
> >                 return;
> > 
> > +       if (gpu->mmu_context)
> > +               etnaviv_iommu_context_put(gpu->mmu_context);
> > +       gpu->mmu_context = etnaviv_iommu_context_get(context);
> > +
> 
> I have seen this pattern now more than two times - maybe put the
> assignment of a new mmu context into its own function?
> 
Yea, I thought about having some Gallium style reference handling
functions, but that would change the code even more. Since I intend to
have this series go into stable I wanted to keep the changes to a
minimum for now. I was already on the fence with the first patch in
this series, but that one provides very obvious legibility
improvements, making it easier to review this series.

Would you agree to leave it like that for the stable series and clean
it up in a follow up change?

Regards,
Lucas

> >         gpu_write(gpu, VIVS_MMUv2_PTA_ADDRESS_LOW,
> >                   lower_32_bits(context->global->v2.pta_dma));
> >         gpu_write(gpu, VIVS_MMUv2_PTA_ADDRESS_HIGH,
> > --
> > 2.30.2
> > 
> 
>