[PATCH] drm/i915/display: use old bpp as a base when modeset is not allowed

[Lee, Shawn C]

This patch works properly. Thanks!

Tested-by: Shawn C Lee <shawn.c.lee at intel.com>

>
>We are currently observing failure on refresh rate change on VRR setup if full modeset is not allowed. This is caused by the mismatch in bpp configured by GOP and bpp value calculated by our driver. Changing bpp to value calculated by our driver would require full mode set.
>
>We don't have mechanism to communicate current bpp to userspace -> Userspace can't request to use current bpp. Changing bpp means full modeset. This becomes a problem when userspace haven't allowed full mode set.
>
>Complete solution here would mean adding mechanism to communicate current bpp to userspace. User space should use this bpp to avoid changing bpp if it wants to avoid full mode set.
>
>Tackle this for now in our driver by using existing bpp if full modeset is not allowed.
>
>Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
>---
> drivers/gpu/drm/i915/display/intel_display.c | 33 ++++++++++++++------
> 1 file changed, 23 insertions(+), 10 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
>index 9049b9a1209d8..7b805998b280a 100644
>--- a/drivers/gpu/drm/i915/display/intel_display.c
>+++ b/drivers/gpu/drm/i915/display/intel_display.c
>@@ -4385,21 +4385,34 @@ compute_baseline_pipe_bpp(struct intel_atomic_state *state,
> 			  struct intel_crtc *crtc)
> {
> 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
>-	struct intel_crtc_state *crtc_state =
>+	struct intel_crtc_state *new_crtc_state =
> 		intel_atomic_get_new_crtc_state(state, crtc);
>+	struct intel_crtc_state *old_crtc_state =
>+		intel_atomic_get_old_crtc_state(state, crtc);
> 	struct drm_connector *connector;
> 	struct drm_connector_state *connector_state;
> 	int bpp, i;
> 
>-	if ((IS_G4X(dev_priv) || IS_VALLEYVIEW(dev_priv) ||
>-	    IS_CHERRYVIEW(dev_priv)))
>-		bpp = 10*3;
>-	else if (DISPLAY_VER(dev_priv) >= 5)
>-		bpp = 12*3;
>-	else
>-		bpp = 8*3;
>+	/*
>+	 * TODO: We don't have mechanism to communicate current bpp to
>+	 * userspace -> Userspace can't request to use current bpp. Changing bpp
>+	 * means full modeset. This becomes a problem when userspace wants to
>+	 * avoid full modeset. Tackle this on our driver by using existing bpp
>+	 * if full modeset is not allowed.
>+	 */
>+	if (!state->base.allow_modeset) {
>+		bpp = old_crtc_state->pipe_bpp;
>+	} else {
>+		if ((IS_G4X(dev_priv) || IS_VALLEYVIEW(dev_priv) ||
>+		     IS_CHERRYVIEW(dev_priv)))
>+			bpp = 10 * 3;
>+		else if (DISPLAY_VER(dev_priv) >= 5)
>+			bpp = 12 * 3;
>+		else
>+			bpp = 8 * 3;
>+	}
> 
>-	crtc_state->pipe_bpp = bpp;
>+	new_crtc_state->pipe_bpp = bpp;
> 
> 	/* Clamp display bpp to connector max bpp */
> 	for_each_new_connector_in_state(&state->base, connector, connector_state, i) { @@ -4408,7 +4421,7 @@ compute_baseline_pipe_bpp(struct intel_atomic_state *state,
> 		if (connector_state->crtc != &crtc->base)
> 			continue;
> 
>-		ret = compute_sink_pipe_bpp(connector_state, crtc_state);
>+		ret = compute_sink_pipe_bpp(connector_state, new_crtc_state);
> 		if (ret)
> 			return ret;
> 	}
>--
>2.34.1
>