On Mon, 27 Feb 2023, Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > Remove the bogus csync check and replace it with something that: > - triggers for all forms of csync, not just the basic analog variant > - actually populates the mode csync flags so that drivers can > decide what to do with the mode > > Originally the code tried to outright reject csync, but that > apparently broke some bogus LCD monitor that claimed to have > a detailed mode that uses analog csync, despite also claiming > the monitor only support separate sync: > https://bugzilla.redhat.com/show_bug.cgi?id=540024 > Potentially that monitor should just be quirked or something. > > Anyways, what we are dealing with now is some kind of funny i915 > JSL machine with eDP where the panel claims to support a sensible > 60Hz separate sync mode, and a 50Hz mode with bipolar analog > csync. The 50Hz mode does not work so we want to not use it. > Easiest way is to just correctly flag it as csync and the driver > will reject it. > > TODO: or should we just reject any form of csync (or at least > the analog variants) for digital display interfaces? > > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8146 > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > --- > drivers/gpu/drm/drm_edid.c | 23 +++++++++++++++-------- > include/drm/drm_edid.h | 12 +++++++++--- > 2 files changed, 24 insertions(+), 11 deletions(-) > > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c > index ebab862b8b1a..fa20b1107ce3 100644 > --- a/drivers/gpu/drm/drm_edid.c > +++ b/drivers/gpu/drm/drm_edid.c > @@ -3424,10 +3424,6 @@ static struct drm_display_mode *drm_mode_detailed(struct drm_connector *connecto > connector->base.id, connector->name); > return NULL; > } > - if (!(pt->misc & DRM_EDID_PT_SEPARATE_SYNC)) { > - drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Composite sync not supported\n", > - connector->base.id, connector->name); > - } > > /* it is incorrect if hsync/vsync width is zero */ > if (!hsync_pulse_width || !vsync_pulse_width) { > @@ -3474,10 +3470,21 @@ static struct drm_display_mode *drm_mode_detailed(struct drm_connector *connecto > if (info->quirks & EDID_QUIRK_DETAILED_SYNC_PP) { > mode->flags |= DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC; > } else { > - mode->flags |= (pt->misc & DRM_EDID_PT_HSYNC_POSITIVE) ? > - DRM_MODE_FLAG_PHSYNC : DRM_MODE_FLAG_NHSYNC; > - mode->flags |= (pt->misc & DRM_EDID_PT_VSYNC_POSITIVE) ? > - DRM_MODE_FLAG_PVSYNC : DRM_MODE_FLAG_NVSYNC; > + switch (pt->misc & DRM_EDID_PT_SYNC_MASK) { > + case DRM_EDID_PT_ANALOG_CSYNC: > + case DRM_EDID_PT_BIPOLAR_ANALOG_CSYNC: > + case DRM_EDID_PT_DIGITAL_CSYNC: > + drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Composite sync!\n", > + connector->base.id, connector->name); > + mode->flags |= DRM_MODE_FLAG_CSYNC | DRM_MODE_FLAG_NCSYNC; Not sure it makes a huge difference, and I expect this case to be rare, but what's the _N_ CSYNC based on here? I also observe the spec appears to indicate "Horizontal Sync is Negative (outside of V-sync)" and "Horizontal Sync is Positive (outside of V-sync)" bit is valid also for Digital Composite Sync. See how the bits for vertical sync have "1 1 0" or "1 1 1" but for horizontal sync it's "1 _ _ 0" and "1 _ _ 1". Does that indicate the polarity for digital composite sync?! The spec is not super clear. > + break; > + case DRM_EDID_PT_DIGITAL_SEPARATE_SYNC: > + mode->flags |= (pt->misc & DRM_EDID_PT_HSYNC_POSITIVE) ? > + DRM_MODE_FLAG_PHSYNC : DRM_MODE_FLAG_NHSYNC; > + mode->flags |= (pt->misc & DRM_EDID_PT_VSYNC_POSITIVE) ? > + DRM_MODE_FLAG_PVSYNC : DRM_MODE_FLAG_NVSYNC; I think this is the good stuff, we shouldn't be looking at these flags and setting PHSYNC/NHSYNC/PVSYNC/NVSYNC unless we have digital separate sync. Overall I think Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx> Although it's not all completely clear. But I think being explicit is better than assuming something and simply debug logging about csync and not really doing anything about it. > + break; > + } > } > > set_size: > diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h > index 70ae6c290bdc..49ee10272603 100644 > --- a/include/drm/drm_edid.h > +++ b/include/drm/drm_edid.h > @@ -61,9 +61,15 @@ struct std_timing { > u8 vfreq_aspect; > } __attribute__((packed)); > > -#define DRM_EDID_PT_HSYNC_POSITIVE (1 << 1) > -#define DRM_EDID_PT_VSYNC_POSITIVE (1 << 2) > -#define DRM_EDID_PT_SEPARATE_SYNC (3 << 3) > +#define DRM_EDID_PT_SYNC_MASK (3 << 3) > +# define DRM_EDID_PT_ANALOG_CSYNC (0 << 3) > +# define DRM_EDID_PT_BIPOLAR_ANALOG_CSYNC (1 << 3) > +# define DRM_EDID_PT_DIGITAL_CSYNC (2 << 3) > +# define DRM_EDID_PT_CSYNC_ON_RGB (1 << 1) /* analog csync only */ > +# define DRM_EDID_PT_CSYNC_SERRATE (1 << 2) > +# define DRM_EDID_PT_DIGITAL_SEPARATE_SYNC (3 << 3) > +# define DRM_EDID_PT_HSYNC_POSITIVE (1 << 1) > +# define DRM_EDID_PT_VSYNC_POSITIVE (1 << 2) > #define DRM_EDID_PT_STEREO (1 << 5) > #define DRM_EDID_PT_INTERLACED (1 << 7) -- Jani Nikula, Intel Open Source Graphics Center
