Re: [Intel-gfx] [PATCH 01/20] drm/i915/fbc: Eliminate racy intel_fbc_is_active() usage

[Kahola, Mika]

> -Original Message-
> From: Intel-gfx  On Behalf Of Ville
> Syrjala
> Sent: Wednesday, November 24, 2021 1:37 PM
> To: intel-gfx@lists.freedesktop.org
> Subject: [Intel-gfx] [PATCH 01/20] drm/i915/fbc: Eliminate racy
> intel_fbc_is_active() usage
> 
> From: Ville Syrjälä 
> 
> The ilk fbc watermark computation uses intel_fbc_is_active() which is racy 
> since
> we don't know whether FBC will be enabled or not at some point. So let's just
> assume it will be if both HAS_FBC() and the modparam agree.
> 
> Signed-off-by: Ville Syrjälä 

Reviewed-by: Mika Kahola 

> ---
>  drivers/gpu/drm/i915/intel_pm.c | 9 ++---
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 01fa3fac1b57..18fbdd204a93 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3369,13 +3369,8 @@ static void ilk_wm_merge(struct drm_i915_private
> *dev_priv,
>   }
> 
>   /* ILK: LP2+ must be disabled when FBC WM is disabled but FBC enabled
> */
> - /*
> -  * FIXME this is racy. FBC might get enabled later.
> -  * What we should check here is whether FBC can be
> -  * enabled sometime later.
> -  */
> - if (DISPLAY_VER(dev_priv) == 5 && !merged->fbc_wm_enabled &&
> - intel_fbc_is_active(_priv->fbc)) {
> + if (DISPLAY_VER(dev_priv) == 5 && HAS_FBC(dev_priv) &&
> + dev_priv->params.enable_fbc && !merged->fbc_wm_enabled) {
>   for (level = 2; level <= max_level; level++) {
>   struct intel_wm_level *wm = >wm[level];
> 
> --
> 2.32.0

[Intel-gfx] [PATCH 01/20] drm/i915/fbc: Eliminate racy intel_fbc_is_active() usage

[Ville Syrjala]

From: Ville Syrjälä 

The ilk fbc watermark computation uses intel_fbc_is_active() which
is racy since we don't know whether FBC will be enabled or not at
some point. So let's just assume it will be if both HAS_FBC()
and the modparam agree.

Signed-off-by: Ville Syrjälä 
---
 drivers/gpu/drm/i915/intel_pm.c | 9 ++---
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 01fa3fac1b57..18fbdd204a93 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3369,13 +3369,8 @@ static void ilk_wm_merge(struct drm_i915_private 
*dev_priv,
}
 
/* ILK: LP2+ must be disabled when FBC WM is disabled but FBC enabled */
-   /*
-* FIXME this is racy. FBC might get enabled later.
-* What we should check here is whether FBC can be
-* enabled sometime later.
-*/
-   if (DISPLAY_VER(dev_priv) == 5 && !merged->fbc_wm_enabled &&
-   intel_fbc_is_active(_priv->fbc)) {
+   if (DISPLAY_VER(dev_priv) == 5 && HAS_FBC(dev_priv) &&
+   dev_priv->params.enable_fbc && !merged->fbc_wm_enabled) {
for (level = 2; level <= max_level; level++) {
struct intel_wm_level *wm = >wm[level];
 
-- 
2.32.0