On 11/10/11 9:55 AM, Christopher White wrote:
> On 11/10/11 8:55 AM, Wu Fengguang wrote:
>> On Thu, Nov 10, 2011 at 03:33:50PM +0800, Wu Fengguang wrote:
>>> Wow I reproduced the bug and got a very interesting dmesg:
>>>
>>> gfx =>         [ 4561.287980] [drm:intel_write_eld], ELD on 
>>> [CONNECTOR:12:HDMI-A-2], [ENCODER:11:TMDS-11]
>>> gfx =>         [ 4561.291730] [drm:ironlake_write_eld], ELD on pipe B
>>> gfx =>         [ 4561.293804] [drm:ironlake_write_eld], Audio 
>>> directed to unknown port
>>> gfx =>         [ 4561.295273] [drm:ironlake_write_eld],
>>>        alsa =>  [ 4561.295486] HDMI hot plug event: Codec=3 Pin=6 
>>> Presence_Detect=1 ELD_Valid=0
>>>        alsa =>  [ 4561.295564] HDMI status: Codec=3 Pin=6 
>>> Presence_Detect=1 ELD_Valid=0
>>> gfx =>         [ 4561.300020] ELD size 13
>>>        alsa =>  [ 4561.300697] HDMI hot plug event: Codec=3 Pin=6 
>>> Presence_Detect=1 ELD_Valid=1
>>>        alsa =>  [ 4561.303322] HDMI status: Codec=3 Pin=6 
>>> Presence_Detect=1 ELD_Valid=1
>>>        alsa =>  [ 4561.311120] ALSA hda_eld.c:259 HDMI: Unknown ELD 
>>> version 0
>>>
>>> Hey the two parts are interleaved!
>>>
>>> But still it should work all fine, since the gfx driver does
>>>
>>>          set ELD_Valid = 0
>>>          write ELD
>>>          set ELD_Valid = 1
>>>
>>> So the audio driver would read the correct ELD unless the ELD content
>>> and flag writes are somehow _reordered_ underneath. Or the ELD content
>>> writes take some time to take effect?
>> Just confirmed that adding 1s delay can fix it!
>>
>> New dmesg is:
>>
>> [   48.564923] [drm:drm_crtc_helper_set_mode], [ENCODER:11:TMDS-11] 
>> set [MODE:34:]
>> [   48.567481] [drm:intel_hdmi_mode_set], Enabling HDMI audio on pipe B
>> [   48.568975] [drm:intel_write_eld], ELD on [CONNECTOR:12:HDMI-A-2], 
>> [ENCODER:11:TMDS-11]
>> [   48.571728] [drm:ironlake_write_eld], ELD on pipe B
>> [   48.572882] [drm:ironlake_write_eld], Audio directed to unknown port
>> [   48.575252] [drm:ironlake_write_eld],
>> [   48.575400] HDMI hot plug event: Codec=3 Pin=6 Presence_Detect=1 
>> ELD_Valid=0
>> [   48.575487] HDMI status: Codec=3 Pin=6 Presence_Detect=1 ELD_Valid=0
>> [   48.580116] ELD size 13
>> [   48.580795] HDMI hot plug event: Codec=3 Pin=6 Presence_Detect=1 
>> ELD_Valid=1
>> [   48.583340] HDMI status: Codec=3 Pin=6 Presence_Detect=1 ELD_Valid=1
>> [   48.632514] [drm:intel_wait_for_vblank], vblank wait timed out
>> [   48.685322] [drm:intel_wait_for_vblank], vblank wait timed out
>> [   48.687438] [drm:ironlake_update_wm], FIFO watermarks For pipe A - 
>> plane 5, cursor: 6
>> [   48.687438] [drm:ironlake_update_wm], FIFO watermarks For pipe A - 
>> plane 5, cursor: 6
>> [   48.690106] [drm:ironlake_update_wm], FIFO watermarks For pipe B - 
>> plane 42, cursor: 6
>> [   48.745204] [drm:intel_wait_for_vblank], vblank wait timed out
>> [   48.798035] [drm:intel_wait_for_vblank], vblank wait timed out
>> [   48.799633] [drm:ironlake_fdi_link_train], FDI_RX_IIR 0x100
>> [   48.802686] [drm:ironlake_fdi_link_train], FDI train 1 done.
>> [   48.805103] [drm:ironlake_fdi_link_train], FDI_RX_IIR 0x600
>> [   48.807246] [drm:ironlake_fdi_link_train], FDI train 2 done.
>> [   48.809426] [drm:ironlake_fdi_link_train], FDI train done
>> [   48.813960] [drm:intel_update_fbc],
>> [   48.814782] [drm:drm_crtc_helper_set_config], Setting connector 
>> DPMS state to on
>> [   48.818093] [drm:drm_crtc_helper_set_config],        
>> [CONNECTOR:12:HDMI-A-2] set DPMS on
>> [   48.828633] [drm:intel_prepare_page_flip], preparing flip with no 
>> unpin work?
>> [   49.618962] HDMI: detected monitor RX-V1800 at connection type HDMI
>> [   49.621013] HDMI: available speakers: FL/FR LFE FC RL/RR RC RLC/RRC
>> [   49.622304] HDMI: supports coding type LPCM: channels = 2, rates = 
>> 32000 44100 48000 96000 176400 192000 384000, bits = 16 20 24
>> [   49.625069] HDMI: supports coding type LPCM: channels = 8, rates = 
>> 32000 44100 48000 96000 176400 192000 384000, bits = 16 20 24
>> [   49.628535] HDMI: supports coding type AC-3: channels = 6, rates = 
>> 32000 44100 48000, max bitrate = 640000
>> [   49.630810] HDMI: supports coding type DTS: channels = 7, rates = 
>> 32000 44100 48000 96000 176400, max bitrate = 1536000
>> [   49.633148] HDMI: supports coding type DSD (One Bit Audio): 
>> channels = 6, rates = 44100
>> [   49.635039] HDMI: supports coding type E-AC-3/DD+ (Dolby Digital 
>> Plus): channels = 8, rates = 44100 48000
>> [   49.637130] HDMI: supports coding type MLP (Dolby TrueHD): 
>> channels = 8, rates = 48000 176400 384000
>> [   49.639172] HDMI: supports coding type DTS-HD: channels = 8, rates 
>> = 48000 176400 384000
>>
>> Thanks,
>> Fengguang
> Wow, you were able to reproduce it! That's the best news ever. I will 
> be applying this patch and rebuilding now to see what happens. So it 
> was some sort of timing issue after all.
>
> Expect me to reply within 1h, but rebuild takes some time.
I still had the old build directory and only had to rebuild one module 
which only took 5 minutes. The rest of the delay was me doing an hour of 
tests as well as being on a 45 minute phone call. Anyway, now the result:

Success!

So we know it's a timing issue somewhere. Wow, real progress and near a 
solution. Finally! The big question now is what causes the audio driver 
to read the ELD while it is empty, and why the 1 second delay fixes it.

Look at speakertest.txt here. It's beautiful. ;-) Playing digital 
multichannel sound over the HDMI PCH bus, and I can hear every channel 
in their proper location on my speaker system. It's beautiful. I've 
waited for this moment since building this Linux HTPC back in April. ;-) 
(I'm an astonishingly patient man hehe).

Now as for why we needed a 1 second delay, any ideas? Could it be that 
the audio driver was reading the ELD while it wasn't written to the 
register yet?


Christopher