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linux/drivers/gpu/drm/stm
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Marek Vasut 9f075cb088 drm/stm: Fix bus_flags handling 
[ Upstream commit 99e360442f ]

The drm_display_mode_to_videomode() does not populate DISPLAY_FLAGS_DE_LOW
or DISPLAY_FLAGS_PIXDATA_NEGEDGE flags in struct videomode. Therefore, no
matter what polarity the next bridge or display might require, these flags
are never set, and thus the LTDC GCR_DEPOL and GCR_PCPOL bits are never set
and the LTDC behaves as if both DISPLAY_FLAGS_PIXDATA_POSEDGE and
DISPLAY_FLAGS_DE_HIGH were always set.

The fix for this problem is taken almost verbatim from MXSFB driver. In
case there is a bridge attached to the LTDC, the bridge might have extra
polarity requirements, so extract bus_flags from the bridge and use them
for LTDC configuration. Otherwise, extract bus_flags from the connector,
which is the display.

Fixes: b759012c5f ("drm/stm: Add STM32 LTDC driver")
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Antonio Borneo <antonio.borneo@st.com>
Cc: Benjamin Gaignard <benjamin.gaignard@st.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Philippe Cornu <philippe.cornu@st.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Vincent Abriou <vincent.abriou@st.com>
Cc: Yannick Fertre <yannick.fertre@st.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-stm32@st-md-mailman.stormreply.com
To: dri-devel@lists.freedesktop.org
Tested-by: Yannick Fertre <yannick.fertre@foss.st.com>
Signed-off-by: Philippe Cornu <philippe.cornu@foss.st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210127110756.125570-1-marex@denx.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2021-05-14 09:50:22 +02:00
..
drv.c drm/stm: Set GEM CMA functions with DRM_GEM_CMA_DRIVER_OPS_WITH_DUMB_CREATE 2020-06-10 09:05:32 +02:00
dw_mipi_dsi-stm.c drm/stm: dsi: stm mipi dsi doesn't print error on probe deferral 2020-02-04 11:47:43 +01:00
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
ltdc.c drm/stm: Fix bus_flags handling 2021-05-14 09:50:22 +02:00
ltdc.h drm/stm: Convert to struct drm_crtc_helper_funcs.get_scanout_position() 2020-02-13 13:09:22 +01:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00