On Monday, December 13, 2021 at 02:36 p.m, Ville Syrjälä wrote: >On Mon, Dec 13, 2021 at 02:09:33PM +0000, Lee, Shawn C wrote: >> >> On Monday, December 13, 2021 at 12:45 p.m, Ville Syrjälä wrote: >> >On Mon, Dec 13, 2021 at 12:42:22PM +0000, Lee, Shawn C wrote: >> >> >> >> On Monday, December 13, 2021 8:31 PM, Ville Syrjälä wrote: >> >> >On Sun, Dec 12, 2021 at 11:33:31PM +0800, Lee Shawn C wrote: >> >> >> According to CEA-861-F chapter 7.5.4. It says "The VSDB shall contain >> >> >> the >> >> >> 3 bytes of the IEEE OUI as well as any additional payload bytes needed." >> >> >> Now DRM driver check HDMI OUI but VSDB payload size at least five bytes. >> >> >> That may caused some HDMI monitors' audio feature can't be enabled. >> >> >> Because of they only have three bytes payload (OUI only) in VSDB. >> >> > >> >> >HDMI 1.4a says >> >> >"Sinks shall contain an HDMI VSDB minimally containing a 2-byte Source Physical Address field following the 24-bit identifier. ... >> >> > The minimum value of N (length) is 5 and the maximum value of N is 31." >> >> > >> >> >Do you actually have an EDID that violates that? >> >> > >> >> >> >> Yes! User report when connect to HDMI port on Acer V226HQL. Audio is not working. >> >> But windows system did not have the same problem. We found its VSDB just have 3 bytes >> >> payload (OUI). Then we share this patch to user then they report audio works properly >> >> with this patch. >> > >> >Hrm. This deserves a comment then since it clearly violates the spec. >> >Also a link to the bug if you have one would be nice to include here. >> > >> >> Let me create an issue and update monitor's EDID for you reference. >> But I'm not sure which community is suitable to report this problem. >> It looks to me should belong to DRM driver https://gitlab.freedesktop.org/drm/misc/-/issues. > >That seems fine to me. > Here is the link, thanks! https://gitlab.freedesktop.org/drm/misc/-/issues/28 >> Do you have any suggestion? Thanks! >> >> >> >> >> Best regards, >> >> Shawn >> >> >> >> >> >> >> >> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> >> >> >> Cc: Adam Jackson <ajax@xxxxxxxxxx> >> >> >> Cc: Dave Airlie <airlied@xxxxxxxxxx> >> >> >> Signed-off-by: Lee Shawn C <shawn.c.lee@xxxxxxxxx> >> >> >> --- >> >> >> drivers/gpu/drm/drm_edid.c | 2 +- >> >> >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> >> >> >> >> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c >> >> >> index 12893e7be89b..5aa4a6bf4a13 100644 >> >> >> --- a/drivers/gpu/drm/drm_edid.c >> >> >> +++ b/drivers/gpu/drm/drm_edid.c >> >> >> @@ -4205,7 +4205,7 @@ static bool cea_db_is_hdmi_vsdb(const u8 *db) >> >> >> if (cea_db_tag(db) != VENDOR_BLOCK) >> >> >> return false; >> >> >> >> >> >> - if (cea_db_payload_len(db) < 5) >> >> >> + if (cea_db_payload_len(db) < 3) >> >> >> return false; >> >> >> >> >> >> return oui(db[3], db[2], db[1]) == HDMI_IEEE_OUI; >> >> >> -- >> >> >> 2.31.1 >> >> > >> >> >-- >> >> >Ville Syrjälä >> >> >Intel >> >> > >
