Hi Marek.
On Sat, Oct 03, 2020 at 01:07:26AM +0200, Marek Vasut wrote:
The drm_display_mode_to_videomode() does not populate DISPLAY_FLAGS_DE_LOW or DISPLAY_FLAGS_PIXDATA_NEGEDGE flags in struct videomode.
So after reading this paragrahp I assumed this patch would fix this, alas there is no changes to drm_modes.c. Rather than introducing hacks could we try to fix the root cause here?
Root cause - as you point out is that there is missing some flags in the conversion. Another point is that the stm driver could drop the use of drm_display_mode_to_videomode() - all the information is available in drm_display_mode and using drm_display_mode_to_videomode() does not help much.
If the point is to have easier access to hsync and friendns maybe we should have a few helpers operating direct on display_mode and not this conversion to video_mode which is something that belongs to fbdev and should IMO not be used inside a drm driver.
Sam
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 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
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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