linux-kernel - [PATCH v4 09/17] drm/bridge: cdns-dsi: Drop checks that shouldn't be in .mode

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Message-Id: <20250618-cdns-dsi-impro-v4-9-862c841dbe02@ideasonboard.com>
Date: Wed, 18 Jun 2025 12:59:12 +0300
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>, 
 Jayesh Choudhary <j-choudhary@...com>, Dmitry Baryshkov <lumag@...nel.org>
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>, 
 Parth Pancholi <parth.pancholi@...adex.com>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Subject: [PATCH v4 09/17] drm/bridge: cdns-dsi: Drop checks that shouldn't
 be in .mode_valid()

The docs say about mode_valid():

"it is not allowed to look at anything else but the passed-in mode, and
validate it against configuration-invariant hardware constraints"

We're doing a lot more than just looking at the mode. The main issue
here is that we're doing checks based on the pixel clock, before we know
what the pixel clock from the crtc actually is.

So, drop the cdns_dsi_check_conf() call from .mode_valid().

Reviewed-by: Aradhya Bhatia <aradhya.bhatia@...ux.dev>
Tested-by: Parth Pancholi <parth.pancholi@...adex.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
---
 drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
index 000c5a2367fe..b2b6529b1c70 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
@@ -603,8 +603,7 @@ cdns_dsi_bridge_mode_valid(struct drm_bridge *bridge,
 	struct cdns_dsi_input *input = bridge_to_cdns_dsi_input(bridge);
 	struct cdns_dsi *dsi = input_to_dsi(input);
 	struct cdns_dsi_output *output = &dsi->output;
-	struct cdns_dsi_cfg dsi_cfg;
-	int bpp, ret;
+	int bpp;
 
 	/*
 	 * VFP_DSI should be less than VFP_DPI and VFP_DSI should be at
@@ -622,10 +621,6 @@ cdns_dsi_bridge_mode_valid(struct drm_bridge *bridge,
 	if ((mode->hdisplay * bpp) % 32)
 		return MODE_H_ILLEGAL;
 
-	ret = cdns_dsi_check_conf(dsi, mode, &dsi_cfg);
-	if (ret)
-		return MODE_BAD;
-
 	return MODE_OK;
 }
 

-- 
2.43.0