| Message ID | 20201002230726.242035-1-marex@denx.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/stm: Fix bus_flags handling | expand |
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 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
On 10/16/20 7:44 PM, Sam Ravnborg wrote: > Hi Marek. Hi, > 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? Nope, this is a driver fix, hence the drm/stm tags. > 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. I kinda already have such a patch in the tree to remove this, but I want to have a patch which fixes the problem described here and can be easily backported to stable too. > 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. Yep, that is for another patch though, because if that one breaks something, I want to be able to bisect it.
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);
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> 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(-)