drm/gma500: Remove struct psb_gtt.sem sempahore

The semaphore at struct psb_mmu_driver.sem protects access to the MMU
fields. Additional locking with struct psb_gtt.sem is unnecessary. Remove
the field and related code.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220308195222.13471-5-tzimmermann@suse.de

drivers/gpu/drm/gma500/gtt.c

@@ -125,12 +125,6 @@ void psb_gtt_remove_pages(struct drm_psb_private *pdev, const struct resource *r
 	mutex_unlock(&pdev->gtt_mutex);
 }
 
-static void psb_gtt_alloc(struct drm_device *dev)
-{
-	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
-	init_rwsem(&dev_priv->gtt.sem);
-}
-
 void psb_gtt_takedown(struct drm_device *dev)
 {
 	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
@@ -166,7 +160,6 @@ int psb_gtt_init(struct drm_device *dev, int resume)
 	if (!resume) {
 		mutex_init(&dev_priv->gtt_mutex);
 		mutex_init(&dev_priv->mmap_mutex);
-		psb_gtt_alloc(dev);
 	}
 
 	pg = &dev_priv->gtt;

drivers/gpu/drm/gma500/gtt.h

@@ -22,7 +22,6 @@ struct psb_gtt {
 	unsigned gatt_pages;
 	unsigned long stolen_size;
 	unsigned long vram_stolen_size;
-	struct rw_semaphore sem;
 };
 
 /* Exported functions */

drivers/gpu/drm/gma500/psb_drv.c

@@ -184,13 +184,11 @@ static void psb_driver_unload(struct drm_device *dev)
 	if (dev_priv->mmu) {
 		struct psb_gtt *pg = &dev_priv->gtt;
 
-		down_read(&pg->sem);
 		psb_mmu_remove_pfn_sequence(
 			psb_mmu_get_default_pd
 			(dev_priv->mmu),
 			pg->mmu_gatt_start,
 			dev_priv->vram_stolen_size >> PAGE_SHIFT);
-		up_read(&pg->sem);
 		psb_mmu_driver_takedown(dev_priv->mmu);
 		dev_priv->mmu = NULL;
 	}
@@ -345,12 +343,10 @@ static int psb_driver_load(struct drm_device *dev, unsigned long flags)
 		return ret;
 
 	/* Add stolen memory to SGX MMU */
-	down_read(&pg->sem);
 	ret = psb_mmu_insert_pfn_sequence(psb_mmu_get_default_pd(dev_priv->mmu),
 					  dev_priv->stolen_base >> PAGE_SHIFT,
 					  pg->gatt_start,
 					  pg->stolen_size >> PAGE_SHIFT, 0);
-	up_read(&pg->sem);
 
 	psb_mmu_set_pd_context(psb_mmu_get_default_pd(dev_priv->mmu), 0);
 	psb_mmu_set_pd_context(dev_priv->pf_pd, 1);