Re: [Intel-gfx] [PATCH 01/11] drm/edid: Handle EDID 1.4 range descriptor h/vfreq offsets

Ville Syrjälä
2022-09-02T13:44:28Z

On Fri, Aug 26, 2022 at 06:40:12PM -0700, Navare, Manasi wrote:
> On Sat, Aug 27, 2022 at 12:34:51AM +0300, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > EDID 1.4 introduced some extra flags in the range
> > descriptor to support min/max h/vfreq >= 255. Consult them
> > to correctly parse the vfreq limits.
> >
> > Note that some combinations of the flags are documented
> > as "reserved" (as are some other values in the descriptor)
> > but explicitly checking for those doesn't seem particularly
> > worthwile since we end up with bogus results whether we
> > decode them or not.
> >
> > v2: Increase the storage to u16 to make it work (Jani)
> > Note the "reserved" values situation (Jani)
> > v3: Document the EDID version number in the defines
> > Drop some bogus (u8) casts
> >
> > Cc: stable@vger.kernel.org
> > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6519
> > Reviewed-by: Jani Nikula <jani.nikula@intel.com>
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> > drivers/gpu/drm/drm_debugfs.c | 4 ++--
> > drivers/gpu/drm/drm_edid.c | 24 ++++++++++++++++++------
> > include/drm/drm_connector.h | 4 ++--
> > include/drm/drm_edid.h | 5 +++++
> > 4 files changed, 27 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
> > index 493922069c90..01ee3febb813 100644
> > --- a/drivers/gpu/drm/drm_debugfs.c
> > +++ b/drivers/gpu/drm/drm_debugfs.c
> > @@ -377,8 +377,8 @@ static int vrr_range_show(struct seq_file *m, void *data)
> > if (connector->status != connector_status_connected)
> > return -ENODEV;
> >
> > - seq_printf(m, "Min: %u\n", (u8)connector->display_info.monitor_range.min_vfreq);
> > - seq_printf(m, "Max: %u\n", (u8)connector->display_info.monitor_range.max_vfreq);
> > + seq_printf(m, "Min: %u\n", connector->display_info.monitor_range.min_vfreq);
> > + seq_printf(m, "Max: %u\n", connector->display_info.monitor_range.max_vfreq);
> >
> > return 0;
> > }
> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > index 90a5e26eafa8..4005dab6147d 100644
> > --- a/drivers/gpu/drm/drm_edid.c
> > +++ b/drivers/gpu/drm/drm_edid.c
> > @@ -6020,12 +6020,14 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
> > }
> >
> > static
> > -void get_monitor_range(const struct detailed_timing *timing,
> > - void *info_monitor_range)
> > +void get_monitor_range(const struct detailed_timing *timing, void *c)
> > {
> > - struct drm_monitor_range_info *monitor_range = info_monitor_range;
> > + struct detailed_mode_closure *closure = c;
> > + struct drm_display_info *info = &closure->connector->display_info;
> > + struct drm_monitor_range_info *monitor_range = &info->monitor_range;
> > const struct detailed_non_pixel *data = &timing->data.other_data;
> > const struct detailed_data_monitor_range *range = &data->data.range;
> > + const struct edid *edid = closure->drm_edid->edid;
> >
> > if (!is_display_descriptor(timing, EDID_DETAIL_MONITOR_RANGE))
> > return;
> > @@ -6041,18 +6043,28 @@ void get_monitor_range(const struct detailed_timing *timing,
> >
> > monitor_range->min_vfreq = range->min_vfreq;
> > monitor_range->max_vfreq = range->max_vfreq;
> > +
> > + if (edid->revision >= 4) {
> > + if (data->pad2 & DRM_EDID_RANGE_OFFSET_MIN_VFREQ)
> > + monitor_range->min_vfreq += 255;
> > + if (data->pad2 & DRM_EDID_RANGE_OFFSET_MAX_VFREQ)
> > + monitor_range->max_vfreq += 255;
>
> Yes this makes sense. This looks like added for supporting HRR (high
> refresh rate) panels.
> Do you think we should mention that in the commit message or in the
> comment in the code itself?

Didn't really see any need for that. Should be fairly obvious
a single u8 alone can't represent big values.

>
> Other than that looks good to me:
>
> Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>

Thanks. Pushed this one to drm-misc-fixes.

>
> Manasi
>
> > + }
> > }
> >
> > static void drm_get_monitor_range(struct drm_connector *connector,
> > const struct drm_edid *drm_edid)
> > {
> > - struct drm_display_info *info = &connector->display_info;
> > + const struct drm_display_info *info = &connector->display_info;
> > + struct detailed_mode_closure closure = {
> > + .connector = connector,
> > + .drm_edid = drm_edid,
> > + };
> >
> > if (!version_greater(drm_edid, 1, 1))
> > return;
> >
> > - drm_for_each_detailed_block(drm_edid, get_monitor_range,
> > - &info->monitor_range);
> > + drm_for_each_detailed_block(drm_edid, get_monitor_range, &closure);
> >
> > DRM_DEBUG_KMS("Supported Monitor Refresh rate range is %d Hz - %d Hz\n",
> > info->monitor_range.min_vfreq,
> > diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> > index 248206bbd975..56aee949c6fa 100644
> > --- a/include/drm/drm_connector.h
> > +++ b/include/drm/drm_connector.h
> > @@ -319,8 +319,8 @@ enum drm_panel_orientation {
> > * EDID's detailed monitor range
> > */
> > struct drm_monitor_range_info {
> > - u8 min_vfreq;
> > - u8 max_vfreq;
> > + u16 min_vfreq;
> > + u16 max_vfreq;
> > };
> >
> > /**
> > diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> > index 2181977ae683..1ed61e2b30a4 100644
> > --- a/include/drm/drm_edid.h
> > +++ b/include/drm/drm_edid.h
> > @@ -92,6 +92,11 @@ struct detailed_data_string {
> > u8 str[13];
> > } __attribute__((packed));
> >
> > +#define DRM_EDID_RANGE_OFFSET_MIN_VFREQ (1 << 0) /* 1.4 */
> > +#define DRM_EDID_RANGE_OFFSET_MAX_VFREQ (1 << 1) /* 1.4 */
> > +#define DRM_EDID_RANGE_OFFSET_MIN_HFREQ (1 << 2) /* 1.4 */
> > +#define DRM_EDID_RANGE_OFFSET_MAX_HFREQ (1 << 3) /* 1.4 */
> > +
> > #define DRM_EDID_DEFAULT_GTF_SUPPORT_FLAG 0x00
> > #define DRM_EDID_RANGE_LIMITS_ONLY_FLAG 0x01
> > #define DRM_EDID_SECONDARY_GTF_SUPPORT_FLAG 0x02
> > --
> > 2.35.1
> >

--
Ville Syrjälä
Intel