Re: [PATCH 1/3] drm/vmwgfx: Drop svga_lock

Looks good. Thanks!

Reviewed-by: Zack Rusin zackr@vmware.com

On Jan 12, 2021, at 03:49, Daniel Vetter daniel.vetter@ffwll.ch wrote:

Hi Roland,

Hopefully you had a nice start into the new year! Ping for some review/testing on this series.

Thanks, Daniel

On Fri, Dec 11, 2020 at 5:29 PM Daniel Vetter daniel.vetter@ffwll.ch wrote:

...

This isn't actually protecting anything becuase:

• when running, ttm_resource_manager->use_type is protected through

vmw_private->reservation_semaphore against concurrent execbuf or well anything else that might evict or reserve buffers

• during suspend/resume there's nothing else running, hence

vmw_pm_freeze and vmw_pm_restore do not need to take the same lock.

• this also holds for the SVGA_REG_ENABLE register write

Hence it is safe to just remove that spinlock.

Signed-off-by: Daniel Vetter daniel.vetter@intel.com Cc: VMware Graphics linux-graphics-maintainer@vmware.com Cc: Roland Scheidegger sroland@vmware.com

---

drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 10 +--------- drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 1 - 2 files changed, 1 insertion(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c index 0008be02d31c..204f7a1830f0 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c @@ -672,7 +672,6 @@ static int vmw_driver_load(struct drm_device *dev, unsigned long chipset) spin_lock_init(&dev_priv->hw_lock); spin_lock_init(&dev_priv->waiter_lock); spin_lock_init(&dev_priv->cap_lock);

•   spin_lock_init(&dev_priv->svga_lock);
   spin_lock_init(&dev_priv->cursor_lock);
  
   for (i = vmw_res_context; i < vmw_res_max; ++i) {
  

@@ -1189,12 +1188,10 @@ static void __vmw_svga_enable(struct vmw_private *dev_priv) { struct ttm_resource_manager *man = ttm_manager_type(&dev_priv->bdev, TTM_PL_VRAM);

•   spin_lock(&dev_priv->svga_lock);
   if (!ttm_resource_manager_used(man)) {
           vmw_write(dev_priv, SVGA_REG_ENABLE, SVGA_REG_ENABLE);
           ttm_resource_manager_set_used(man, true);
   }
  

•   spin_unlock(&dev_priv->svga_lock);
  

}

/** @@ -1220,14 +1217,12 @@ static void __vmw_svga_disable(struct vmw_private *dev_priv) { struct ttm_resource_manager *man = ttm_manager_type(&dev_priv->bdev, TTM_PL_VRAM);

•   spin_lock(&dev_priv->svga_lock);
   if (ttm_resource_manager_used(man)) {
           ttm_resource_manager_set_used(man, false);
           vmw_write(dev_priv, SVGA_REG_ENABLE,
                     SVGA_REG_ENABLE_HIDE |
                     SVGA_REG_ENABLE_ENABLE);
   }
  

•   spin_unlock(&dev_priv->svga_lock);
  

}

/** @@ -1254,17 +1249,14 @@ void vmw_svga_disable(struct vmw_private *dev_priv) */ vmw_kms_lost_device(dev_priv->dev); ttm_write_lock(&dev_priv->reservation_sem, false);

•   spin_lock(&dev_priv->svga_lock);
   if (ttm_resource_manager_used(man)) {
           ttm_resource_manager_set_used(man, false);
  

•           spin_unlock(&dev_priv->svga_lock);
           if (ttm_resource_manager_evict_all(&dev_priv->bdev, man))
                   DRM_ERROR("Failed evicting VRAM buffers.\n");
           vmw_write(dev_priv, SVGA_REG_ENABLE,
                     SVGA_REG_ENABLE_HIDE |
                     SVGA_REG_ENABLE_ENABLE);
  

•   } else
  

•           spin_unlock(&dev_priv->svga_lock);
  

•   }
   ttm_write_unlock(&dev_priv->reservation_sem);
  

}

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h index 5b9a28157dd3..715f2bfee08a 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h @@ -596,7 +596,6 @@ struct vmw_private {

   bool stealth;
   bool enable_fb;

•   spinlock_t svga_lock;
  
   /**
    * PM management.
  

-- 2.29.2

-- Daniel Vetter Software Engineer, Intel Corporation https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fblog.ffwll....