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: b759012c5fa7 ("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 --- V2: Check if ldev->bridge->timings is non-NULL before accessing it V3: get bus_flags from connector (from Yannick) - Display controller could support several connectors (not connected at the same time). ie: stm32mp15c-DK2 board have 2 connectors (HDMI + DSI). Driver check which connector is connected to get the bus flag. V4: get bridge from encoder (from Yannick) --- drivers/gpu/drm/stm/ltdc.c | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c index 6e28e6b60e72..acc9f6694eb6 100644 --- a/drivers/gpu/drm/stm/ltdc.c +++ b/drivers/gpu/drm/stm/ltdc.c @@ -544,13 +544,42 @@ static void ltdc_crtc_mode_set_nofb(struct drm_crtc *crtc) { struct ltdc_device *ldev = crtc_to_ltdc(crtc); struct drm_device *ddev = crtc->dev; + struct drm_connector_list_iter iter; + struct drm_connector *connector = NULL; + struct drm_encoder *encoder = NULL; + struct drm_bridge *bridge = NULL; struct drm_display_mode *mode = &crtc->state->adjusted_mode; struct videomode vm; u32 hsync, vsync, accum_hbp, accum_vbp, accum_act_w, accum_act_h; u32 total_width, total_height; + u32 bus_flags = 0; u32 val; int ret;
+ /* get encoder from crtc */ + drm_for_each_encoder(encoder, ddev) + if (encoder->crtc == crtc) + break; + + if (encoder) { + /* get bridge from encoder */ + list_for_each_entry(bridge, &encoder->bridge_chain, chain_node) + if (bridge->encoder == encoder) + break; + + /* Get the connector from encoder */ + drm_connector_list_iter_begin(ddev, &iter); + drm_for_each_connector_iter(connector, &iter) + if (connector->encoder == encoder) + break; + drm_connector_list_iter_end(&iter); + } + + if (bridge && bridge->timings) + bus_flags = bridge->timings->input_bus_flags; + else if (connector) + bus_flags = connector->display_info.bus_flags; + if (!pm_runtime_active(ddev->dev)) { ret = pm_runtime_get_sync(ddev->dev); if (ret) { @@ -586,10 +615,10 @@ static void ltdc_crtc_mode_set_nofb(struct drm_crtc *crtc) if (vm.flags & DISPLAY_FLAGS_VSYNC_HIGH) val |= GCR_VSPOL;
- if (vm.flags & DISPLAY_FLAGS_DE_LOW) + if (bus_flags & DRM_BUS_FLAG_DE_LOW) val |= GCR_DEPOL;
- if (vm.flags & DISPLAY_FLAGS_PIXDATA_NEGEDGE) + if (bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE) val |= GCR_PCPOL;
reg_update_bits(ldev->regs, LTDC_GCR,