FAILED: patch "[PATCH] drm/i915: set DP Main Stream Attribute for color range on DDI" failed to apply to 4.19-stable tree

From 6209c285e7a5e68dbcdf8fd2456c6dd68433806b Mon Sep 17 00:00:00 2001

The patch below does not apply to the 4.19-stable tree.

If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6209c285e7a5e68dbcdf8fd2456c6dd68433806b Mon Sep 17 00:00:00 2001
From: Jani Nikula <[email protected]>
Date: Tue, 14 Aug 2018 09:00:01 +0300
Subject: [PATCH] drm/i915: set DP Main Stream Attribute for color range on DDI
platforms
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Since Haswell we have no color range indication either in the pipe or port registers for DP. Instead, there's a separate register for setting the DP Main Stream Attributes (MSA) directly. The MSA register definition makes no references to colorimetry, just a vague reference to the DP spec. The connection to the color range was lost.

Apparently we've failed to set the proper MSA bit for limited, or CEA, range ever since the first DDI platforms. We've started setting other MSA parameters since commit dae847991a43 ("drm/i915: add intel_ddi_set_pipe_settings").

Without the crucial bit of information, the DP sink has no way of knowing the source is actually transmitting limited range RGB, leading to "washed out" colors. With the colorimetry information, compliant sinks should be able to handle the limited range properly. Native (i.e. non-LSPCON) HDMI was not affected because we do pass the color range via AVI infoframes.

Though not the root cause, the problem was made worse for DDI platforms with commit 55bc60db5988 ("drm/i915: Add "Automatic" mode for the "Broadcast RGB" property"), which selects limited range RGB automatically based on the mode, as per the DP, HDMI and CEA specs.

After all these years, the fix boils down to flipping one bit.

[Per testing reports, this fixes DP sinks, but not the LSPCON. My
educated guess is that the LSPCON fails to turn the CEA range MSA into AVI infoframes for HDMI.]

Reported-by Michał Kopeć <[email protected]>

Reported-by N. W. <[email protected]>

Reported-by Nicholas Stommel <[email protected]>

Reported-by Tom Yan <[email protected]>

Tested-by Nicholas Stommel <[email protected]>

References: https://bugs.freedesktop.org/show_bug.cgi?id=100023
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107476
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=94921

Cc Paulo Zanoni <[email protected]>

Cc Rodrigo Vivi <[email protected]>

Cc Ville Syrjälä <[email protected]>

Cc <[email protected]> # v3.9+

Reviewed-by Rodrigo Vivi <[email protected]>

Signed-off-by Jani Nikula <[email protected]>

Link https://patchwork.freedesktop.org/patch/msgid/[email protected]

(cherry picked from commit dc5977da99ea28094b8fa4e9bacbd29bedc41de5)

Signed-off-by Rodrigo Vivi <[email protected]>

drivers/gpu/drm/i915/i915_reg.h +1 -0

index 91e7483228e1..08ec7446282e 100644
@@ -9201,6 +9201,7 @@ enum skl_power_gate {
 #define  TRANS_MSA_10_BPC		(2 << 5)
 #define  TRANS_MSA_12_BPC		(3 << 5)
 #define  TRANS_MSA_16_BPC		(4 << 5)
+#define  TRANS_MSA_CEA_RANGE		(1 << 3)
 
 /* LCPLL Control */
 #define LCPLL_CTL			_MMIO(0x130040)

drivers/gpu/drm/i915/intel_ddi.c +4 -0

index 39d66f8493fa..8761513f3532 100644
@@ -1685,6 +1685,10 @@ void intel_ddi_set_pipe_settings(const struct intel_crtc_state *crtc_state)
 	WARN_ON(transcoder_is_dsi(cpu_transcoder));
 
 	temp = TRANS_MSA_SYNC_CLK;
+
+	if (crtc_state->limited_color_range)
+		temp |= TRANS_MSA_CEA_RANGE;
+
 	switch (crtc_state->pipe_bpp) {
 	case 18:
 		temp |= TRANS_MSA_6_BPC;

Quoted 1 line · On Wed, 12 Sep 2018, [email protected] wrote:

The patch below does not apply to the 4.19-stable tree.

Err what? There's no v4.19 stable release yet and the commit in question is in v4.19-rc1. Did I miss a memo?