[PATCH 3/7] drm/vmwgfx: Stop using plane->fb in vmw_kms_helper_dirty()

[Thomas Hellstrom]

On 04/05/2018 09:50 PM, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Instead of plane->fb (which we're going to deprecate for atomic drivers)
> we need to look at plane->state->fb. The maze of code leading to
> vmw_kms_helper_dirty() wasn't particularly clear, but my analysis
> concluded that the calls originating from vmw_*_primary_plane_atomic_update()
> all pass in the crtc which means we'll never end up in this branch
> of the function. All other callers use drm_modeset_lock_all() somewhere
> higher up, which means accessing plane->state is safe. We'll toss in
> a lockdep assert to catch wrongdoers.
>
> Cc: Thomas Hellstrom <thellstrom at vmware.com>
> Cc: Sinclair Yeh <syeh at vmware.com>
> Cc: VMware Graphics <linux-graphics-maintainer at vmware.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>   drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 15 ++++++++++++---
>   1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> index a2a796b4cc23..5a824125c231 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> @@ -2326,9 +2326,18 @@ int vmw_kms_helper_dirty(struct vmw_private *dev_priv,
>   	} else {
>   		list_for_each_entry(crtc, &dev_priv->dev->mode_config.crtc_list,
>   				    head) {
> -			if (crtc->primary->fb != &framebuffer->base)
> -				continue;
> -			units[num_units++] = vmw_crtc_to_du(crtc);
> +			struct drm_plane *plane = crtc->primary;
> +
> +			/*
> +			 * vmw_*_primary_plane_atomic_update() pass in the crtc,
> +			 * and so don't end up here. All other callers use
> +			 * drm_modeset_lock_all(), hence we can access the
> +			 * plane state safely.
> +			 */
> +			lockdep_assert_held(&plane->mutex);
> +
I think we can remove the comment (it's a helper, so current users may 
not be future users),
but the lockdep assert should be OK.
> +			if (plane->state->fb != &framebuffer->base)
> +				units[num_units++] = vmw_crtc_to_du(crtc);

This doesn't seem to do what the original code did...

>   		}
>   	}
>   

/Thomas