From cdf26e1462c220629bb79d487263b66f8b679eab Mon Sep 17 00:00:00 2001 From: Marek Vasut Date: Sat, 10 Jan 2026 18:14:10 +0100 Subject: [PATCH] drm/imx: parallel-display: Prefer bus format set via legacy "interface-pix-fmt" DT property Prefer bus format set via legacy "interface-pix-fmt" DT property over panel bus format. This is necessary to retain support for DTs which configure the IPUv3 parallel output as 24bit DPI, but connect 18bit DPI panels to it with hardware swizzling. This used to work up to Linux 6.12, but stopped working in 6.13, reinstate the behavior to support old DTs. Cc: stable@vger.kernel.org Fixes: 5f6e56d3319d ("drm/imx: parallel-display: switch to drm_panel_bridge") Signed-off-by: Marek Vasut Reviewed-by: Philipp Zabel Signed-off-by: Philipp Zabel Link: https://patch.msgid.link/20260110171510.692666-1-marex@nabladev.com --- drivers/gpu/drm/imx/ipuv3/parallel-display.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/imx/ipuv3/parallel-display.c b/drivers/gpu/drm/imx/ipuv3/parallel-display.c index 4ce772bc3cb3..a356f0b764cb 100644 --- a/drivers/gpu/drm/imx/ipuv3/parallel-display.c +++ b/drivers/gpu/drm/imx/ipuv3/parallel-display.c @@ -110,8 +110,7 @@ imx_pd_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge, output_fmt = imxpd->bus_format ? : MEDIA_BUS_FMT_RGB888_1X24; /* Now make sure the requested output format is supported. */ - if ((imxpd->bus_format && imxpd->bus_format != output_fmt) || - !imx_pd_format_supported(output_fmt)) { + if (!imx_pd_format_supported(output_fmt)) { *num_input_fmts = 0; return NULL; } @@ -121,7 +120,17 @@ imx_pd_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge, if (!input_fmts) return NULL; - input_fmts[0] = output_fmt; + /* + * Prefer bus format set via legacy "interface-pix-fmt" DT property + * over panel bus format. This is necessary to retain support for + * DTs which configure the IPUv3 parallel output as 24bit, but + * connect 18bit DPI panels to it with hardware swizzling. + */ + if (imxpd->bus_format && imxpd->bus_format != output_fmt) + input_fmts[0] = imxpd->bus_format; + else + input_fmts[0] = output_fmt; + return input_fmts; }