Patch "drm/i915: Fix scaler init during CRTC HW state readout" has been added to the 4.12-stable tree

This is a note to let you know that I've just added the patch titled

drm/i915: Fix scaler init during CRTC HW state readout

to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-i915-fix-scaler-init-during-crtc-hw-state-readout.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Imre Deak <[email protected]>
Date: Thu, 20 Jul 2017 14:28:20 +0300
Subject: drm/i915: Fix scaler init during CRTC HW state readout
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From: Imre Deak <[email protected]>

commit 283d6860d64f5091565bf729b0a6d6af14ae6c27 upstream.

The scaler allocation code depends on a non-zero default value for the crtc scaler_id, so make sure we initialize the scaler state accordingly even if the crtc is off. This fixes at least an initial YUV420 modeset (added in a follow-up patchset by Shashank) when booting with the screen
off: after the initial HW readout and modeset which enables the scaler a subsequent modeset will disable the scaler which isn't properly allocated. This results in a funky HW state where the pipe scaler HW registers can't be modified and the normally black screen is grey and shifted to the right or jitters.

The problem was revealed by Shashank's YUV420 patchset and first reported by Ville.

v2:
- In the stable tag also include versions which need backporting (Jani)

---
 drivers/gpu/drm/i915/intel_display.c |   14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

@@ -9085,6 +9085,13 @@ static bool haswell_get_pipe_config(stru
 	u64 power_domain_mask;
 	bool active;
 
+	if (INTEL_GEN(dev_priv) >= 9) {
+		intel_crtc_init_scalers(crtc, pipe_config);
+
+		pipe_config->scaler_state.scaler_id = -1;
+		pipe_config->scaler_state.scaler_users &= ~(1 << SKL_CRTC_INDEX);
+	}
+
 	power_domain = POWER_DOMAIN_PIPE(crtc->pipe);
 	if (!intel_display_power_get_if_enabled(dev_priv, power_domain))
 		return false;

@@ -9113,13 +9120,6 @@ static bool haswell_get_pipe_config(stru
 	pipe_config->gamma_mode =
 		I915_READ(GAMMA_MODE(crtc->pipe)) & GAMMA_MODE_MODE_MASK;
 
-	if (INTEL_GEN(dev_priv) >= 9) {
-		intel_crtc_init_scalers(crtc, pipe_config);
-
-		pipe_config->scaler_state.scaler_id = -1;
-		pipe_config->scaler_state.scaler_users &= ~(1 << SKL_CRTC_INDEX);
-	}
-
 	power_domain = POWER_DOMAIN_PIPE_PANEL_FITTER(crtc->pipe);
 	if (intel_display_power_get_if_enabled(dev_priv, power_domain)) {
 		power_domain_mask |= BIT_ULL(power_domain);

Patches currently in stable-queue which might be from [email protected] are

queue-4.12/drm-i915-fix-scaler-init-during-crtc-hw-state-readout.patch