[Intel-gfx] [PATCH v2] drm/i915/display: relax 2big checking around initial fb

[Lee, Shawn C]

On Wed, 26 May 2021 at 12:49 p.m, Matthew Auld <matthew.auld at intel.com> wrote:

>From: Chris Wilson <chris at chris-wilson.co.uk>
>
>The kernel prefers enabling fbc over the initial fb, since this leads to actual runtime power savings, so if the initial fb is deemed too big using some heuristic, then we simply skip allocating stolen for it.
>However if the kernel is not configured with fbcon then it should be possible to relax this, since unlike with fbcon the display server shouldn't preserve it when later replacing it, and so we should be able to re-use the stolen memory for fbc and friends. This patch is reported to fix some flicker seen during boot splash on some devices.
>
>v2: s/FRAMEBUFFER_CONSOLE/CONFIG_FRAMEBUFFER_CONSOLE
>
>Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>Signed-off-by: Matthew Auld <matthew.auld at intel.com>
>Cc: Lee Shawn C <shawn.c.lee at intel.com>
>Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
>Cc: Daniel Vetter <daniel.vetter at intel.com>
>Reviewed-by: Imre Deak <imre.deak at intel.com>

Verify on my DUT and no flicker issue seen during boot splash. Thanks!

>---
> drivers/gpu/drm/i915/display/intel_display.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
>index 0bb2e582c87f..db97a92dc84e 100644
>--- a/drivers/gpu/drm/i915/display/intel_display.c
>+++ b/drivers/gpu/drm/i915/display/intel_display.c
>@@ -1690,7 +1690,8 @@ initial_plane_vma(struct drm_i915_private *i915,
> 	 * important and we should probably use that space with FBC or other
> 	 * features.
> 	 */
>-	if (size * 2 > i915->stolen_usable_size)
>+	if (IS_ENABLED(CONFIG_FRAMEBUFFER_CONSOLE) &&
>+	    size * 2 > i915->stolen_usable_size)
> 		return NULL;
> 
> 	obj = i915_gem_object_create_stolen_for_preallocated(i915, base, size);
>--
>2.26.3
>