[PATCH 10/26] drm/i915: fix the __intel_fbc_update() comments

Paulo Zanoni
2015-10-27T16:50:55Z

Don't try to list in comments the cases where we should enable or
disable FBC: it varies a lot with the hardware generations and the
code should be the documentation. Also notice that there's already a
huge gap between the comments and what's in the code.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
drivers/gpu/drm/i915/intel_fbc.c | 26 ++------------------------
1 file changed, 2 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index 06bdc27..1b39037 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -861,20 +861,8 @@ static bool intel_fbc_hw_tracking_covers_screen(struct intel_crtc *crtc)
* __intel_fbc_update - enable/disable FBC as needed, unlocked
* @dev_priv: i915 device instance
*
- * Set up the framebuffer compression hardware at mode set time. We
- * enable it if possible:
- * - plane A only (on pre-965)
- * - no pixel mulitply/line duplication
- * - no alpha buffer discard
- * - no dual wide
- * - framebuffer <= max_hdisplay in width, max_vdisplay in height
- *
- * We can't assume that any compression will take place (worst case),
- * so the compressed buffer has to be the same size as the uncompressed
- * one. It also must reside (along with the line length buffer) in
- * stolen memory.
- *
- * We need to enable/disable FBC on a global basis.
+ * This function completely reevaluates the status of FBC, then enables,
+ * disables or maintains it on the same state.
*/
static void __intel_fbc_update(struct drm_i915_private *dev_priv)
{
@@ -886,7 +874,6 @@ static void __intel_fbc_update(struct drm_i915_private *dev_priv)

WARN_ON(!mutex_is_locked(&dev_priv->fbc.lock));

- /* disable framebuffer compression in vGPU */
if (intel_vgpu_active(dev_priv->dev))
i915.enable_fbc = 0;

@@ -900,15 +887,6 @@ static void __intel_fbc_update(struct drm_i915_private *dev_priv)
goto out_disable;
}

- /*
- * If FBC is already on, we just have to verify that we can
- * keep it that way...
- * Need to disable if:
- * - more than one pipe is active
- * - changing FBC params (stride, fence, mode)
- * - new fb is too large to fit in compressed buffer
- * - going to an unsupported config (interlace, pixel multiply, etc.)
- */
drm_crtc = intel_fbc_find_crtc(dev_priv);
if (!drm_crtc) {
set_no_fbc_reason(dev_priv, "no output");