On Fri, 11 Mar 2016, Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > [ text/plain ] > On Fri, Mar 11, 2016 at 03:36:48PM +0200, Jani Nikula wrote: >> On Wed, 09 Mar 2016, ville.syrjala@xxxxxxxxxxxxxxx wrote: >> > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> >> > >> > 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 sink’s 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@xxxxxxxxx> >> > Tested-by: Arturo Pérez <artur999555@xxxxxxxxx> >> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94197 >> > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> >> > --- >> > 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@xxxxxxxxx> 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. 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 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
