Re: [PATCH v4 04/13] drm/panfrost: Move shrinker initialization and unplug one level down

["Adrián Larumbe" <adrian.larumbe@collabora.com>]

Hi Steven,

On 30.07.2026 11:39, Steven Price wrote:
> On 29/07/2026 03:54, Adrián Larumbe wrote:
> > Since the moment we call drm_dev_register() the device should be in a
> > position to accept jobs, so it's best if the shrinker is already
> > initialized by then.
> > 
> > On top of that, make shrinker functions take an panfrost_device pointer
> > like other functions in the same sequence and rename them accordingly.
> > 
> > Essentially mimic the init/fini behaviour in Panthor.
> > 
> > Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
> > ---
> >  drivers/gpu/drm/panfrost/panfrost_device.c       |  8 +++++++-
> >  drivers/gpu/drm/panfrost/panfrost_drv.c          |  6 ------
> >  drivers/gpu/drm/panfrost/panfrost_gem.c          | 19 ++++++++++---------
> >  drivers/gpu/drm/panfrost/panfrost_gem.h          |  6 +++---
> >  drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c |  8 ++------
> >  5 files changed, 22 insertions(+), 25 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
> > index d8421fd6a662..03905495aee2 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_device.c
> > +++ b/drivers/gpu/drm/panfrost/panfrost_device.c
> > @@ -281,9 +281,14 @@ int panfrost_device_init(struct panfrost_device *pfdev)
> >  	if (err)
> >  		goto out_job;
> >  
> > -	panfrost_gem_init(pfdev);
> > +	err = panfrost_gem_init(pfdev);
> > +	if (err)
> > +		goto out_perfcnt;
> >  
> >  	return 0;
> > +
> > +out_perfcnt:
> > +	panfrost_perfcnt_fini(pfdev);
> >  out_job:
> >  	panfrost_jm_fini(pfdev);
> >  out_mmu:
> > @@ -305,6 +310,7 @@ int panfrost_device_init(struct panfrost_device *pfdev)
> >  
> >  void panfrost_device_fini(struct panfrost_device *pfdev)
> >  {
> > +	panfrost_gem_shrinker_fini(pfdev);
> >  	panfrost_perfcnt_fini(pfdev);
> >  	panfrost_jm_fini(pfdev);
> >  	panfrost_mmu_fini(pfdev);
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> > index 2e931fa90da0..331a3bd5b98c 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> > +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> > @@ -1002,14 +1002,9 @@ static int panfrost_probe(struct platform_device *pdev)
> >  	if (err < 0)
> >  		goto err_out1;
> >  
> > -	err = panfrost_gem_shrinker_init(&pfdev->base);
> > -	if (err)
> > -		goto err_out2;
> >  
> >  	return 0;
> >  
> > -err_out2:
> > -	drm_dev_unregister(&pfdev->base);
> >  err_out1:
> >  	pm_runtime_disable(pfdev->base.dev);
> >  	panfrost_device_fini(pfdev);
> > @@ -1023,7 +1018,6 @@ static void panfrost_remove(struct platform_device *pdev)
> >  	struct panfrost_device *pfdev = platform_get_drvdata(pdev);
> >  
> >  	drm_dev_unregister(&pfdev->base);
> > -	panfrost_gem_shrinker_cleanup(&pfdev->base);
> >  
> >  	pm_runtime_get_sync(pfdev->base.dev);
> >  	pm_runtime_disable(pfdev->base.dev);
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
> > index 3a7fce428898..aa3a604b3439 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
> > +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
> > @@ -15,20 +15,21 @@
> >  #include "panfrost_gem.h"
> >  #include "panfrost_mmu.h"
> >  
> > -void panfrost_gem_init(struct panfrost_device *pfdev)
> > +int panfrost_gem_init(struct panfrost_device *pfdev)
> >  {
> >  	int err;
> >  
> >  	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
> > -	    !panfrost_transparent_hugepage)
> > -		return;
> > +	    panfrost_transparent_hugepage) {
> 
> Note you haven't quite inverted the condition here, but I don't think
> the new condition is wrong - we skip the otherwise no-op helpers. The
> old condition seems a bit backward. Indeed I'm not really sure why we
> bother with the IS_ENABLED() check at all. But the new code looks fine.

I've heeded your advice and done away with the IS_ENABLED() check in v5.
I'm curious about why that would work though. Is it because the linker initialises
symbols marked as 'extern' to 0 when they aren't resolved?

Otherwise I would've assumed the compiler would throw out a missing definition
error at link time, but then again I'm unsure about this.

> Reviewed-by: Steven Price <steven.price@arm.com>
> 
> Thanks,
> Steve
> 
> > +		err = drm_gem_huge_mnt_create(&pfdev->base, "within_size");
> > +		if (drm_gem_get_huge_mnt(&pfdev->base))
> > +			drm_info(&pfdev->base, "Using Transparent Hugepage\n");
> > +		else if (err)
> > +			drm_warn(&pfdev->base,
> > +				 "Can't use Transparent Hugepage (%d)\n", err);
> > +	}
> >  
> > -	err = drm_gem_huge_mnt_create(&pfdev->base, "within_size");
> > -	if (drm_gem_get_huge_mnt(&pfdev->base))
> > -		drm_info(&pfdev->base, "Using Transparent Hugepage\n");
> > -	else if (err)
> > -		drm_warn(&pfdev->base, "Can't use Transparent Hugepage (%d)\n",
> > -			 err);
> > +	return panfrost_gem_shrinker_init(pfdev);
> >  }
> >  
> >  #ifdef CONFIG_DEBUG_FS
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
> > index 79d4377019e9..d6e55c2e4d86 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_gem.h
> > +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
> > @@ -129,7 +129,7 @@ drm_mm_node_to_panfrost_mapping(struct drm_mm_node *node)
> >  	return container_of(node, struct panfrost_gem_mapping, mmnode);
> >  }
> >  
> > -void panfrost_gem_init(struct panfrost_device *pfdev);
> > +int panfrost_gem_init(struct panfrost_device *pfdev);
> >  
> >  struct drm_gem_object *panfrost_gem_create_object(struct drm_device *dev, size_t size);
> >  
> > @@ -154,8 +154,8 @@ panfrost_gem_mapping_get(struct panfrost_gem_object *bo,
> >  void panfrost_gem_mapping_put(struct panfrost_gem_mapping *mapping);
> >  void panfrost_gem_teardown_mappings_locked(struct panfrost_gem_object *bo);
> >  
> > -int panfrost_gem_shrinker_init(struct drm_device *dev);
> > -void panfrost_gem_shrinker_cleanup(struct drm_device *dev);
> > +int panfrost_gem_shrinker_init(struct panfrost_device *pfdev);
> > +void panfrost_gem_shrinker_fini(struct panfrost_device *pfdev);
> >  
> >  void panfrost_gem_set_label(struct drm_gem_object *obj, const char *label);
> >  int panfrost_gem_sync(struct drm_gem_object *obj, u32 type,
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> > index 2fe967a90bcb..fefae87535d6 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> > +++ b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> > @@ -95,10 +95,8 @@ panfrost_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
> >   *
> >   * This function registers and sets up the panfrost shrinker.
> >   */
> > -int panfrost_gem_shrinker_init(struct drm_device *dev)
> > +int panfrost_gem_shrinker_init(struct panfrost_device *pfdev)
> >  {
> > -	struct panfrost_device *pfdev = to_panfrost_device(dev);
> > -
> >  	pfdev->shrinker = shrinker_alloc(0, "drm-panfrost");
> >  	if (!pfdev->shrinker)
> >  		return -ENOMEM;
> > @@ -118,10 +116,8 @@ int panfrost_gem_shrinker_init(struct drm_device *dev)
> >   *
> >   * This function unregisters the panfrost shrinker.
> >   */
> > -void panfrost_gem_shrinker_cleanup(struct drm_device *dev)
> > +void panfrost_gem_shrinker_fini(struct panfrost_device *pfdev)
> >  {
> > -	struct panfrost_device *pfdev = to_panfrost_device(dev);
> > -
> >  	if (pfdev->shrinker)
> >  		shrinker_free(pfdev->shrinker);
> >  }
> > 

Adrian Larumbe