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

[Zack Rusin]

Looks good. Thanks!

Reviewed-by: Zack Rusin <zackr at vmware.com>

> On Jan 12, 2021, at 03:49, Daniel Vetter <daniel.vetter at 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 at 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 at intel.com>
>> Cc: VMware Graphics <linux-graphics-maintainer at vmware.com>
>> Cc: Roland Scheidegger <sroland at 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
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