linux-kernel - [PATCH RESEND] drm: bridge: dw-mipi-dsi: Allow sync-pulses to override the burst vid-mode

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Date: Wed, 26 Jun 2024 10:47:22 +0200
From: Heiko Stuebner <heiko@...ech.de>
To: andrzej.hajda@...el.com,
	neil.armstrong@...aro.org,
	rfoss@...nel.org
Cc: Laurent.pinchart@...asonboard.com,
	jonas@...boo.se,
	jernej.skrabec@...il.com,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	victor.liu@....com,
	quentin.schulz@...rry.de,
	heiko@...ech.de,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Heiko Stuebner <heiko.stuebner@...rry.de>
Subject: [PATCH RESEND] drm: bridge: dw-mipi-dsi: Allow sync-pulses to override the burst vid-mode

From: Heiko Stuebner <heiko.stuebner@...rry.de>

The state right now is that if the panel has the burst-mode flag it
will take precedence over the sync-pulses mode.

While sync-pulses are only relevant for the video-mode, the burst-mode
flag affects both the video-mode as well as the calculated lane_mbps.

Looking at drivers like the nwl-dsi [0] it only enables burst mode when
the panel's flags do not contain the sync_pulse flag.

So handle things similar for dw-dsi in that it selects the video-mode
with sync-pulses if that flag is set and only after that, checks for
the burst-mode. So panels selecting a combination of both burst and
sync-pulses get the sync-pulse mode.

The case this fixes can be found on the ltk050h3148w . It does need the
lane-rate to be calculated according to burst formulas [1], but without
sync-pulses we see the output shifted around 20 pixels to the right,
meaning that the last 20 pixels from each line appear at the start of
the next display line.

[0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/bridge/nwl-dsi.c#n301
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6c9dbee84cd005bed5f9d07b3a2797ae6414b435

Fixes: 93e82bb4de01 ("drm/bridge: synopsys: dw-mipi-dsi: Fix hcomponent lbcc for burst mode")
Signed-off-by: Heiko Stuebner <heiko.stuebner@...rry.de>
---
resend, because I messed up and somehow forgot to include _all_
mailing lists.

 drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
index 824fb3c65742e..28dd858a751bd 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
@@ -605,10 +605,10 @@ static void dw_mipi_dsi_video_mode_config(struct dw_mipi_dsi *dsi)
 	 */
 	val = ENABLE_LOW_POWER;

-	if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_BURST)
-		val |= VID_MODE_TYPE_BURST;
-	else if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
+	if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
 		val |= VID_MODE_TYPE_NON_BURST_SYNC_PULSES;
+	else if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_BURST)
+		val |= VID_MODE_TYPE_BURST;
 	else
 		val |= VID_MODE_TYPE_NON_BURST_SYNC_EVENTS;

-- 
2.39.2