Re: [PATCH] drm/v3d: Enable V3D to use different PAGE_SIZE

[Maíra Canal <mcanal@xxxxxxxxxx>]

Hi Iago,

On 2/19/24 09:56, Iago Toral wrote:
> Hi Maíra,
>
> El mié, 14-02-2024 a las 16:34 -0300, Maíra Canal escribió:
> > Currently, the V3D driver uses PAGE_SHIFT over the assumption that
> > PAGE_SHIFT = 12, as the PAGE_SIZE = 4KB. But, the RPi 5 is using
> > PAGE_SIZE = 16KB, so the MMU PAGE_SHIFT is different than the
> > system's
> > PAGE_SHIFT.
> >
> > Enable V3D to be used in system's with any PAGE_SIZE by making sure
> > that
> > everything MMU-related uses the MMU page shift.
> >
> > Signed-off-by: Maíra Canal <mcanal@xxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/v3d/v3d_bo.c      | 12 ++++++------
> >   drivers/gpu/drm/v3d/v3d_debugfs.c |  2 +-
> >   drivers/gpu/drm/v3d/v3d_drv.h     |  2 ++
> >   drivers/gpu/drm/v3d/v3d_irq.c     |  2 +-
> >   drivers/gpu/drm/v3d/v3d_mmu.c     |  2 --
> >   5 files changed, 10 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/v3d/v3d_bo.c
> > b/drivers/gpu/drm/v3d/v3d_bo.c
> > index 1bdfac8beafd..a07ede668cc1 100644
> > --- a/drivers/gpu/drm/v3d/v3d_bo.c
> > +++ b/drivers/gpu/drm/v3d/v3d_bo.c
>
> I think we need the same change in v3d_get_bo_vaddr, no?

No, that one uses the PAGE_SHIFT of the CPU, because obj->pages is in
the CPU.

Best Regards,
- Maíra

> Iago
>
> > @@ -40,7 +40,7 @@ void v3d_free_object(struct drm_gem_object *obj)
> >
> >   	mutex_lock(&v3d->bo_lock);
> >   	v3d->bo_stats.num_allocated--;
> > -	v3d->bo_stats.pages_allocated -= obj->size >> PAGE_SHIFT;
> > +	v3d->bo_stats.pages_allocated -= obj->size >>
> > V3D_MMU_PAGE_SHIFT;
> >   	mutex_unlock(&v3d->bo_lock);
> >
> >   	spin_lock(&v3d->mm_lock);
> > @@ -109,8 +109,8 @@ v3d_bo_create_finish(struct drm_gem_object *obj)
> >   	 * lifetime of the BO.
> >   	 */
> >   	ret = drm_mm_insert_node_generic(&v3d->mm, &bo->node,
> > -					 obj->size >> PAGE_SHIFT,
> > -					 GMP_GRANULARITY >>
> > PAGE_SHIFT, 0, 0);
> > +					 obj->size >>
> > V3D_MMU_PAGE_SHIFT,
> > +					 GMP_GRANULARITY >>
> > V3D_MMU_PAGE_SHIFT, 0, 0);
> >   	spin_unlock(&v3d->mm_lock);
> >   	if (ret)
> >   		return ret;
> > @@ -118,7 +118,7 @@ v3d_bo_create_finish(struct drm_gem_object *obj)
> >   	/* Track stats for /debug/dri/n/bo_stats. */
> >   	mutex_lock(&v3d->bo_lock);
> >   	v3d->bo_stats.num_allocated++;
> > -	v3d->bo_stats.pages_allocated += obj->size >> PAGE_SHIFT;
> > +	v3d->bo_stats.pages_allocated += obj->size >>
> > V3D_MMU_PAGE_SHIFT;
> >   	mutex_unlock(&v3d->bo_lock);
> >
> >   	v3d_mmu_insert_ptes(bo);
> > @@ -201,7 +201,7 @@ int v3d_create_bo_ioctl(struct drm_device *dev,
> > void *data,
> >   	if (IS_ERR(bo))
> >   		return PTR_ERR(bo);
> >
> > -	args->offset = bo->node.start << PAGE_SHIFT;
> > +	args->offset = bo->node.start << V3D_MMU_PAGE_SHIFT;
> >
> >   	ret = drm_gem_handle_create(file_priv, &bo->base.base,
> > &args->handle);
> >   	drm_gem_object_put(&bo->base.base);
> > @@ -246,7 +246,7 @@ int v3d_get_bo_offset_ioctl(struct drm_device
> > *dev, void *data,
> >   	}
> >   	bo = to_v3d_bo(gem_obj);
> >
> > -	args->offset = bo->node.start << PAGE_SHIFT;
> > +	args->offset = bo->node.start << V3D_MMU_PAGE_SHIFT;
> >
> >   	drm_gem_object_put(gem_obj);
> >   	return 0;
> > diff --git a/drivers/gpu/drm/v3d/v3d_debugfs.c
> > b/drivers/gpu/drm/v3d/v3d_debugfs.c
> > index dc3cf708d02e..19e3ee7ac897 100644
> > --- a/drivers/gpu/drm/v3d/v3d_debugfs.c
> > +++ b/drivers/gpu/drm/v3d/v3d_debugfs.c
> > @@ -219,7 +219,7 @@ static int v3d_debugfs_bo_stats(struct seq_file
> > *m, void *unused)
> >   	seq_printf(m, "allocated bos:          %d\n",
> >   		   v3d->bo_stats.num_allocated);
> >   	seq_printf(m, "allocated bo size (kb): %ld\n",
> > -		   (long)v3d->bo_stats.pages_allocated <<
> > (PAGE_SHIFT - 10));
> > +		   (long)v3d->bo_stats.pages_allocated <<
> > (V3D_MMU_PAGE_SHIFT - 10));
> >   	mutex_unlock(&v3d->bo_lock);
> >
> >   	return 0;
> > diff --git a/drivers/gpu/drm/v3d/v3d_drv.h
> > b/drivers/gpu/drm/v3d/v3d_drv.h
> > index 3c7d58866570..1950c723dde1 100644
> > --- a/drivers/gpu/drm/v3d/v3d_drv.h
> > +++ b/drivers/gpu/drm/v3d/v3d_drv.h
> > @@ -19,6 +19,8 @@ struct reset_control;
> >
> >   #define GMP_GRANULARITY (128 * 1024)
> >
> > +#define V3D_MMU_PAGE_SHIFT 12
> > +
> >   #define V3D_MAX_QUEUES (V3D_CPU + 1)
> >
> >   static inline char *v3d_queue_to_string(enum v3d_queue queue)
> > diff --git a/drivers/gpu/drm/v3d/v3d_irq.c
> > b/drivers/gpu/drm/v3d/v3d_irq.c
> > index afc76390a197..2e04f6cb661e 100644
> > --- a/drivers/gpu/drm/v3d/v3d_irq.c
> > +++ b/drivers/gpu/drm/v3d/v3d_irq.c
> > @@ -70,7 +70,7 @@ v3d_overflow_mem_work(struct work_struct *work)
> >   	list_add_tail(&bo->unref_head, &v3d->bin_job->render-
> > > unref_list);
> >   	spin_unlock_irqrestore(&v3d->job_lock, irqflags);
> >
> > -	V3D_CORE_WRITE(0, V3D_PTB_BPOA, bo->node.start <<
> > PAGE_SHIFT);
> > +	V3D_CORE_WRITE(0, V3D_PTB_BPOA, bo->node.start <<
> > V3D_MMU_PAGE_SHIFT);
> >   	V3D_CORE_WRITE(0, V3D_PTB_BPOS, obj->size);
> >
> >   out:
> > diff --git a/drivers/gpu/drm/v3d/v3d_mmu.c
> > b/drivers/gpu/drm/v3d/v3d_mmu.c
> > index 5a453532901f..14f3af40d6f6 100644
> > --- a/drivers/gpu/drm/v3d/v3d_mmu.c
> > +++ b/drivers/gpu/drm/v3d/v3d_mmu.c
> > @@ -21,8 +21,6 @@
> >   #include "v3d_drv.h"
> >   #include "v3d_regs.h"
> >
> > -#define V3D_MMU_PAGE_SHIFT 12
> > -
> >   /* Note: All PTEs for the 1MB superpage must be filled with the
> >    * superpage bit set.
> >    */
> > --
> > 2.43.0