linux-kernel - [PATCH 10/18] drm/bridge: cdns-dsi: Fix event mode

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Message-Id: <20250320-cdns-dsi-impro-v1-10-725277c5f43b@ideasonboard.com>
Date: Thu, 20 Mar 2025 18:00:05 +0200
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Jyri Sarha <jyri.sarha@....fi>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>, 
 Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 linux-phy@...ts.infradead.org, Francesco Dolcini <francesco@...cini.it>, 
 Aradhya Bhatia <aradhya.bhatia@...ux.dev>, 
 Devarsh Thakkar <devarsht@...com>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Subject: [PATCH 10/18] drm/bridge: cdns-dsi: Fix event mode

The timings calculation gets it wrong for DSI event mode, resulting in
too large hbp value. Fix the issue by taking into account the
pulse/event mode difference.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
---
 drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 33 ++++++++++++++++++--------
 1 file changed, 23 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
index 62811631341b..9797e6faa29d 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
@@ -417,7 +417,8 @@
 #define DSI_OUTPUT_PORT			0
 #define DSI_INPUT_PORT(inputid)		(1 + (inputid))
 
-#define DSI_HBP_FRAME_OVERHEAD		12
+#define DSI_HBP_FRAME_PULSE_OVERHEAD	12
+#define DSI_HBP_FRAME_EVENT_OVERHEAD	16
 #define DSI_HSA_FRAME_OVERHEAD		14
 #define DSI_HFP_FRAME_OVERHEAD		6
 #define DSI_HSS_VSS_VSE_FRAME_OVERHEAD	4
@@ -503,12 +504,18 @@ static int cdns_dsi_mode2cfg(struct cdns_dsi *dsi,
 
 	bpp = mipi_dsi_pixel_format_to_bpp(output->dev->format);
 
-	dsi_cfg->hbp = dpi_to_dsi_timing(dpi_hbp + (sync_pulse ? 0 : dpi_hsa),
-					 bpp, DSI_HBP_FRAME_OVERHEAD);
+	if (sync_pulse) {
+		dsi_cfg->hbp = dpi_to_dsi_timing(dpi_hbp, bpp,
+						 DSI_HBP_FRAME_PULSE_OVERHEAD);
 
-	if (sync_pulse)
-		dsi_cfg->hsa =
-			dpi_to_dsi_timing(dpi_hsa, bpp, DSI_HSA_FRAME_OVERHEAD);
+		dsi_cfg->hsa = dpi_to_dsi_timing(dpi_hsa, bpp,
+						 DSI_HSA_FRAME_OVERHEAD);
+	} else {
+		dsi_cfg->hbp = dpi_to_dsi_timing(dpi_hbp + dpi_hsa, bpp,
+						 DSI_HBP_FRAME_EVENT_OVERHEAD);
+
+		dsi_cfg->hsa = 0;
+	}
 
 	dsi_cfg->hact = dpi_to_dsi_timing(dpi_hact, bpp, 0);
 
@@ -532,9 +539,12 @@ static int cdns_dsi_adjust_phy_config(struct cdns_dsi *dsi,
 	unsigned int dsi_hfp_ext;
 	unsigned int lanes = output->dev->lanes;
 
-	dsi_htotal = dsi_cfg->hbp + DSI_HBP_FRAME_OVERHEAD;
-	if (output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
+	if (output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) {
+		dsi_htotal = dsi_cfg->hbp + DSI_HBP_FRAME_PULSE_OVERHEAD;
 		dsi_htotal += dsi_cfg->hsa + DSI_HSA_FRAME_OVERHEAD;
+	} else {
+		dsi_htotal = dsi_cfg->hbp + DSI_HBP_FRAME_EVENT_OVERHEAD;
+	}
 
 	dsi_htotal += dsi_cfg->hact;
 	dsi_htotal += dsi_cfg->hfp + DSI_HFP_FRAME_OVERHEAD;
@@ -607,9 +617,12 @@ static int cdns_dsi_check_conf(struct cdns_dsi *dsi,
 		return -EINVAL;
 	}
 
-	dsi_hss_hsa_hse_hbp = dsi_cfg->hbp + DSI_HBP_FRAME_OVERHEAD;
-	if (output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
+	if (output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) {
+		dsi_hss_hsa_hse_hbp = dsi_cfg->hbp + DSI_HBP_FRAME_PULSE_OVERHEAD;
 		dsi_hss_hsa_hse_hbp += dsi_cfg->hsa + DSI_HSA_FRAME_OVERHEAD;
+	} else {
+		dsi_hss_hsa_hse_hbp = dsi_cfg->hbp + DSI_HBP_FRAME_EVENT_OVERHEAD;
+	}
 
 	/*
 	 * Make sure DPI(HFP) > DSI(HSS+HSA+HSE+HBP) to guarantee that the FIFO

-- 
2.43.0