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@xxxxxxx>
Cc: Alexandre Torgue <alexandre.torgue@xxxxxx>
Cc: Antonio Borneo <antonio.borneo@xxxxxx>
Cc: Benjamin Gaignard <benjamin.gaignard@xxxxxx>
Cc: Maxime Coquelin <mcoquelin.stm32@xxxxxxxxx>
Cc: Philippe Cornu <philippe.cornu@xxxxxx>
Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
Cc: Vincent Abriou <vincent.abriou@xxxxxx>
Cc: Yannick Fertre <yannick.fertre@xxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
To: dri-devel@xxxxxxxxxxxxxxxxxxxxx
---
drivers/gpu/drm/stm/ltdc.c | 22 ++++++++++++++++++++--
drivers/gpu/drm/stm/ltdc.h | 2 ++
2 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index 07c73079293c..a282a1553497 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -546,11 +546,17 @@ static void ltdc_crtc_mode_set_nofb(struct drm_crtc *crtc)
struct drm_device *ddev = crtc->dev;
struct drm_display_mode *mode = &crtc->state->adjusted_mode;
struct videomode vm;
+ u32 bus_flags = 0;
u32 hsync, vsync, accum_hbp, accum_vbp, accum_act_w, accum_act_h;
u32 total_width, total_height;
u32 val;
int ret;
+ if (ldev->bridge)
+ bus_flags = ldev->bridge->timings->input_bus_flags;
+ else if (ldev->connector)
+ bus_flags = ldev->connector->display_info.bus_flags;
+
if (!pm_runtime_active(ddev->dev)) {
ret = pm_runtime_get_sync(ddev->dev);
if (ret) {
@@ -586,10 +592,10 @@ 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,
@@ -1098,6 +1104,8 @@ static const struct drm_encoder_helper_funcs ltdc_encoder_helper_funcs = {
static int ltdc_encoder_init(struct drm_device *ddev, struct drm_bridge *bridge)
{
+ struct ltdc_device *ldev = ddev->dev_private;
+ struct drm_connector_list_iter iter;
struct drm_encoder *encoder;
int ret;
@@ -1119,6 +1127,16 @@ static int ltdc_encoder_init(struct drm_device *ddev, struct drm_bridge *bridge)
return -EINVAL;
}
+ ldev->bridge = bridge;
+
+ /*
+ * Get hold of the connector. This is a bit of a hack, until the bridge
+ * API gives us bus flags and formats.
+ */
+ drm_connector_list_iter_begin(ddev, &iter);
+ ldev->connector = drm_connector_list_iter_next(&iter);
+ drm_connector_list_iter_end(&iter);
+
DRM_DEBUG_DRIVER("Bridge encoder:%d created\n", encoder->base.id);
return 0;
diff --git a/drivers/gpu/drm/stm/ltdc.h b/drivers/gpu/drm/stm/ltdc.h
index f153b908c70e..d0d2c81de29a 100644
--- a/drivers/gpu/drm/stm/ltdc.h
+++ b/drivers/gpu/drm/stm/ltdc.h
@@ -38,6 +38,8 @@ struct ltdc_device {
u32 irq_status;
struct fps_info plane_fpsi[LTDC_MAX_LAYER];
struct drm_atomic_state *suspend_state;
+ struct drm_bridge *bridge;
+ struct drm_connector *connector;
};
int ltdc_load(struct drm_device *ddev);
--
2.28.0
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