Re: [PATCH] ALSA: hda - not use regmap for vendor verb 0x781 of Intel HDMI codec

From: "Lin, Mengdong" <mengdong.lin@intel.com>
To: 'Takashi Iwai' <tiwai@suse.de>
Cc: "'alsa-devel@alsa-project.org'" <alsa-devel@alsa-project.org>
Subject: Re: [PATCH] ALSA: hda - not use regmap for vendor verb 0x781 of Intel HDMI codec
Date: Tue, 14 Apr 2015 03:26:10 +0000	[thread overview]
Message-ID: <F46914AEC2663F4A9BB62374E5EEF8F82B826F6A@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <F46914AEC2663F4A9BB62374E5EEF8F82B826848@SHSMSX101.ccr.corp.intel.com>

> -----Original Message-----
> From: Lin, Mengdong
> Sent: Monday, April 13, 2015 9:30 PM

> > > For HDMI codec on Haswell/Broadwell/Skylake platforms, the vendor
> > > verb
> > > 0x781 is used enable DP 1.2 mode as a fixup if BIOS has not done
> > > this, in function intel_haswell_fixup_enable_dp12(). Otherwise, the
> > > display audio playback will be silent.
> > >
> > > Although the verb 0x781 is added to vendor verbs array, but
> > > snd_hdac_regmap_
> > > encode_verb() will translate it to verb 0xf81 and cause regmap_write
> > > IO failure because 0xf81 is not in the vendor verb array and so will
> > > not be taken as a writable register.
> > >
> > > So this patch no longer uses regmap for verb 0x781 but directly send
> > > this command to enable DP1.2 mode.
> >
> > What if just add INTEL_GET_VENDOR_VERB as a vendor verb?
> 
> Yes, it should work. hda_reg_write will drop the GET bit.
> I'll have a test tomorrow.

> > What if just add INTEL_GET_VENDOR_VERB as a vendor verb?
> 
> Yes, it should work. hda_reg_write will drop the GET bit.
> I'll have a test tomorrow.

Hi Takashi,

I've submitted v2 and v3 patches, both can work one my SKL. Please review.

V2: add INTEL_GET_VENDOR_VERB as a vendor verb as you suggested.
   I verified this on a SKL desktop, on which BIOS does not enable DP1.2 mode by default and so we observed the HDMI/DP audio failure.

V3: set GET bit when adding a vendor verb to the codec regmap
   It also works on my SKL. It's more generic than v2, because I observed other HD-A codecs (Conexant, si3054, sigmatel) also add their own vendor SET verbs and may have the same problem.
   However, I have no chance to verify these codecs since I cannot find platforms with them.

Thanks
Mengdong