Re: [PATCH] ASoC: SOF: Fix snd_sof_ipc_stream_posn()

[Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>]

On Tue, Mar 03, 2020 at 09:36:29AM -0600, Pierre-Louis Bossart wrote:
> 
> 
> > > We're passing "&posn" instead of "posn" so it ends up corrupting
> > > memory instead of doing something useful.
> > [...]
> > >   	/* send IPC to the DSP */
> > >   	err = sof_ipc_tx_message(sdev->ipc,
> > > -				 stream.hdr.cmd, &stream, sizeof(stream), &posn,
> > > +				 stream.hdr.cmd, &stream, sizeof(stream), posn,
> > >   				 sizeof(*posn));
> > 
> > ack, thanks, this is clearly wrong. This function is not used by current
> > platforms, so the bug has gone unnnoticed. Most platforms either rely on
> > direct MMIO queries of the DSP position, or the periodic position updates
> > DSPs send after each ALSA period. This function for host to query DSP
> > position via IPC is thus not used, although it's part of the generic audio
> > DSP IPC interface.
> > 
> > For the SOF folks in CC, I wonder should we keep this function at all?
> > 
> > Anyways, that's probably a longer discussion, so while it's there,
> > the code should be correct, so for the patch:
> > Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
> 
> I checked all the way to 5.2 and it was never used, so indeed wondering what
> the purpose of this function was.

I actually have a patch, removing that function, which I noticed as being unused 
during my VirtIO work. I think it was used by compressed.c before.

Thanks
Guennadi