kernel/linux.git/drivers/gpu/drm/bridge/waveshare-dsi.c, branch v7.1

drm/bridge: waveshare-dsi: Fix signedness bug

2026-03-17T17:04:08+00:00

The function drm_of_get_data_lanes_count_ep() returns negative error codes and dsi->lanes is an unsigned integer, so the check (dsi->lanes < 0) is always impossible. Make the return value of drm_of_get_data_lanes_count_ep() be assigned to ret, check for error, and then assign dsi->lanes to ret. Detected by Smatch: drivers/gpu/drm/bridge/waveshare-dsi.c:70 ws_bridge_attach_dsi() warn: unsigned 'dsi->lanes' is never less than zero. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202603060341.hNj0pl9L-lkp@intel.com/ Fixes: fca11428425e9 ("drm/bridge: waveshare-dsi: Add support for 1..4 DSI data lanes") Signed-off-by: Ethan Tidmore Reviewed-by: Luca Ceresoli Reviewed-by: Marek Vasut Link: https://patch.msgid.link/20260307033245.71666-1-ethantidmore06@gmail.com Signed-off-by: Luca Ceresoli

drm/bridge: waveshare-dsi: Add support for 1..4 DSI data lanes

2026-03-03T13:33:20+00:00

Parse the data lane count out of DT. Limit the supported data lanes to 1..4 which is the maximum available DSI pairs on the connector of any known panels which may use this bridge. Internally, this bridge is an ChipOne ICN6211 which loads its register configuration from a dedicated storage and its I2C does not seem to be accessible. The ICN6211 also supports up to 4 DSI lanes, so this is a hard limit. To avoid any breakage on old DTs where the parsing of data lanes from DT may fail, fall back to the original hard-coded value of 2 lanes and warn user. The lane configuration is preconfigured in the bridge for each of the WaveShare panels. The 13.3" DSI panel works with 4-lane configuration, others seem to use 2-lane configuration. This is a hardware property, so the actual count should come from DT. Reviewed-by: Joseph Guo Signed-off-by: Marek Vasut Reviewed-by: Luca Ceresoli Link: https://patch.msgid.link/20260115024004.660986-2-marek.vasut+renesas@mailbox.org Signed-off-by: Luca Ceresoli

drm/bridge: waveshare-dsi: Register and attach our DSI device at probe

2026-03-03T08:11:14+00:00

In order to avoid any probe ordering issue, the best practice is to move the secondary MIPI-DSI device registration and attachment to the MIPI-DSI host at probe time. Besides solving the probe ordering problems, this makes the bridge work with R-Car DU. The R-Car DU will attempt to locate the DSI host bridge in its own rcar_du_probe()->rcar_du_modeset_init()->rcar_du_encoder_init() by calling of_drm_find_bridge() which calls of_drm_find_and_get_bridge() and iterates over bridge_list to locate the DSI host bridge. However, unless the WS driver calls mipi_dsi_attach() in probe(), the DSI host bridge .attach callback rcar_mipi_dsi_host_attach() is not called and the DSI host bridge is not added into bridge_list. Therefore the of_drm_find_and_get_bridge() called from du_probe() will never find the DSI host bridge and probe will indefinitelly fail with -EPROBE_DEFER. The circular dependency here is, that if rcar_du_encoder_init() would manage to find the DSI host bridge, it would call the WS driver .attach callback ws_bridge_bridge_attach(), but this is too late and can never happen. This change avoids the circular dependency. Reviewed-by: Luca Ceresoli Signed-off-by: Marek Vasut Link: https://patch.msgid.link/20260206125801.78705-1-marek.vasut+renesas@mailbox.org Signed-off-by: Luca Ceresoli

drm/bridge: waveshare-dsi: Fix bailout for devm_drm_bridge_alloc()

2025-09-19T02:52:45+00:00

devm_drm_bridge_alloc() returns ERR_PTR on failure instead of a NULL pointer, so use IS_ERR() to check the returned pointer and turn proper error code on failure by using PTR_ERR(). Fixes: dbdea37add13 ("drm: bridge: Add waveshare DSI2DPI unit driver") Signed-off-by: Liu Ying Reviewed-by: Dmitry Baryshkov Link: https://lore.kernel.org/r/20250806084121.510207-1-victor.liu@nxp.com

drm: bridge: Add waveshare DSI2DPI unit driver

2025-08-06T06:49:33+00:00

Waveshare touchscreen consists of a DPI panel and a driver board. The waveshare driver board consists of ICN6211 and a MCU to convert DSI to DPI and control the backlight. This driver treats the MCU and ICN6211 board as a whole unit. It can support all resolution waveshare DSI2DPI based panel, the timing table should come from 'panel-dpi' panel in the device tree. Signed-off-by: Joseph Guo Suggested-by: Liu Ying Reviewed-by: Neil Armstrong Signed-off-by: Neil Armstrong Link: https://lore.kernel.org/r/20250806-waveshare-v3-3-fd28e01f064f@nxp.com