On Fri, Mar 11, 2016 at 04:24:35PM +0200, Jani Nikula wrote:
> On Fri, 11 Mar 2016, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> > [ text/plain ]
> > On Fri, Mar 11, 2016 at 03:36:48PM +0200, Jani Nikula wrote:
> >> On Wed, 09 Mar 2016, ville.syrjala at linux.intel.com wrote:
> >> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> >> >
> >> > SADs may span multiple CEA audio data blocks in the EDID.
> >> >
> >> > CEA-861-E says:
> >> > "The order of the Data Blocks is not constrained. It is also possible
> >> > to have more than one of a specific type of data block if necessary to
> >> > include all of the descriptors needed to describe the sinkâs
> >> > capabilities."
> >> >
> >> > Each audio data block can carry up to 10 SADs, whereas the ELD SAD limit
> >> > is 15 according to HDA 1.0a spec. So we should support at least two data
> >> > blocks. And apparently some devices take a more liberal interpretation
> >> > and stuff only one SAD per data block even when they would fit into one.
> >> >
> >> > So let's try to extract all the SADs we can fit into the ELD even when
> >> > they span multiple data blocks.
> >> >
> >> > While at it, toss in a comment to explain the 13 byte monitor name
> >> > string limit which confused me at first.
> >> >
> >> > Cc: Arturo Pérez <artur999555 at gmail.com>
> >> > Tested-by: Arturo Pérez <artur999555 at gmail.com>
> >> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94197
> >> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> >> > ---
> >> > drivers/gpu/drm/drm_edid.c | 17 +++++++++++------
> >> > 1 file changed, 11 insertions(+), 6 deletions(-)
> >> >
> >> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> >> > index fdb1eb014586..414d7f61aa05 100644
> >> > --- a/drivers/gpu/drm/drm_edid.c
> >> > +++ b/drivers/gpu/drm/drm_edid.c
> >> > @@ -3308,7 +3308,7 @@ void drm_edid_to_eld(struct drm_connector
> >> > *connector, struct edid *edid)
> >> > u8 *cea;
> >> > u8 *name;
> >> > u8 *db;
> >> > - int sad_count = 0;
> >> > + int total_sad_count = 0;
> >> > int mnl;
> >> > int dbl;
> >> >
> >> > @@ -3322,6 +3322,7 @@ void drm_edid_to_eld(struct drm_connector
> >> > *connector, struct edid *edid)
> >> >
> >> > name = NULL;
> >> > drm_for_each_detailed_block((u8 *)edid, monitor_name, &name);
> >> > + /* max: 13 bytes EDID, 16 bytes ELD */
> >> > for (mnl = 0; name && mnl < 13; mnl++) {
> >> > if (name[mnl] == 0x0a)
> >> > break;
> >> > @@ -3350,11 +3351,15 @@ void drm_edid_to_eld(struct drm_connector
> >> > *connector, struct edid *edid)
> >> > dbl = cea_db_payload_len(db);
> >> >
> >> > switch (cea_db_tag(db)) {
> >> > + int sad_count;
> >> > +
> >> > case AUDIO_BLOCK:
> >> > /* Audio Data Block, contains SADs */
> >> > - sad_count = dbl / 3;
> >> > - if (dbl >= 1)
> >> > - memcpy(eld + 20 + mnl, &db[1],
> >> > dbl);
> >> > + sad_count = min(dbl / 3, 15 -
> >> > total_sad_count);
> >>
> >> What if total_sad_count > 15? At a glance, this seems to self correct by
> >> subtracting the excess every second time... ;)
> >
> > Since sad_count will not exceed 15-total_sad_count, total_sad_count will
> > never
> > exceed 15.
>
> Right. I guess it could be spelled out for folks like me. :/
>
> Reviewed-by: Jani Nikula <jani.nikula at intel.com>
>
> If you run out of things to do (that'll be the day), you could follow up
> with replacing some of the magic here for offsets etc. with the
> DRM_ELD_* defines I added in drm_edid.h.
Applied to drm-misc but not yet pushed since I want to roll forward to
latest drm-next as soon as Dave has merged everything.
-Daniel
>
> BR,
> Jani.
>
>
> >
> >>
> >> BR,
> >> Jani.
> >>
> >> > + if (sad_count >= 1)
> >> > + memcpy(eld + 20 + mnl +
> >> > total_sad_count * 3,
> >> > + &db[1], sad_count * 3);
> >> > + total_sad_count += sad_count;
> >> > break;
> >> > case SPEAKER_BLOCK:
> >> > /* Speaker Allocation Data Block */
> >> > @@ -3371,13 +3376,13 @@ void drm_edid_to_eld(struct drm_connector
> >> > *connector, struct edid *edid)
> >> > }
> >> > }
> >> > }
> >> > - eld[5] |= sad_count << 4;
> >> > + eld[5] |= total_sad_count << 4;
> >> >
> >> > eld[DRM_ELD_BASELINE_ELD_LEN] =
> >> > DIV_ROUND_UP(drm_eld_calc_baseline_block_size(eld), 4);
> >> >
> >> > DRM_DEBUG_KMS("ELD size %d, SAD count %d\n",
> >> > - drm_eld_size(eld), sad_count);
> >> > + drm_eld_size(eld), total_sad_count);
> >> > }
> >> > EXPORT_SYMBOL(drm_edid_to_eld);
> >>
> >> --
> >> Jani Nikula, Intel Open Source Technology Center
>
> --
> Jani Nikula, Intel Open Source Technology Center
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
