[PATCH] drm: mxsfb: Set proper default bus format when using a bridge

From: "Guido Günther" <agx@sigxcpu.org>
To: Marek Vasut <marex@denx.de>, Stefan Agner <stefan@agner.ch>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Sam Ravnborg <sam@ravnborg.org>,
	Lucas Stach <l.stach@pengutronix.de>,
	dri-devel@lists.freedesktop.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH] drm: mxsfb: Set proper default bus format when using a bridge
Date: Tue, 28 Sep 2021 10:55:35 +0200	[thread overview]
Message-ID: <YVLYh/SgBritG/RJ@qwark.sigxcpu.org> (raw)

If a bridge doesn't do any bus format handling MEDIA_BUS_FMT_FIXED is
returned. Fallback to a reasonable default (MEDIA_BUS_FMT_RGB888_1X24) in
that case.

This unbreaks e.g. using mxsfb with the nwl bridge and mipi panels.

Fixes: b776b0f00f24 ("drm: mxsfb: Use bus_format from the nearest bridge if present")

Signed-off-by: Guido Günther <agx@sigxcpu.org>
---

I'll look at what needs to be done in nwl separately but this also
unbreaks other bridge seupts that don't to format negotiation yet.

 drivers/gpu/drm/mxsfb/mxsfb_kms.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index af6c620adf6e..4ef94cf686b0 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -369,6 +369,8 @@ static void mxsfb_crtc_atomic_enable(struct drm_crtc *crtc,
 			drm_atomic_get_new_bridge_state(state,
 							mxsfb->bridge);
 		bus_format = bridge_state->input_bus_cfg.format;
+		if (bus_format == MEDIA_BUS_FMT_FIXED)
+			bus_format = MEDIA_BUS_FMT_RGB888_1X24;
 	}
 
 	/* If there is no bridge, use bus format from connector */
-- 
2.33.0
