[alsa-devel] [PATCH v2 4/8] ASoC: topology: ABI - Add name element to snd_soc_tplg_stream

[Lin, Mengdong]

> -----Original Message-----
> From: Mark Brown [mailto:broonie at kernel.org]
> Sent: Wednesday, October 07, 2015 1:37 AM
> To: Lars-Peter Clausen
> Cc: Koul, Vinod; alsa-devel at alsa-project.org; tiwai at suse.de; Lin, Mengdong;
> liam.r.girdwood at linux.intel.com; Kp, Jeeja; Prusty, Subhransu S; Patel,
> Vedang
> Subject: Re: [alsa-devel] [PATCH v2 4/8] ASoC: topology: ABI - Add name
> element to snd_soc_tplg_stream
> 
> On Tue, Oct 06, 2015 at 06:35:28PM +0200, Lars-Peter Clausen wrote:
> > On 10/06/2015 06:25 PM, Mark Brown wrote:
> 
> > > The problem isn't detecting the error, the point is that if someone
> > > upgrades their kernel and someone changed the DAI link name then
> > > their existing userspace will break.  We don't want that error to be
> > > there to be detected in the first place.
> 
> > Another thing to consider is that the topology firmware might be
> > developed against a non-upstream driver. And in order for the driver
> > to go upstream it needs changes that breaks the ABI interface to the
> > firmware which is already shipped and the vendor might not provide
> > support for updating the firmware file. Having these kind of tightly
> > coupled interdependencies between driver and firmware is quite risky
> business.
> 
> Yeah, I think we're kind of stuck with some degree of fairly tight coupling at
> some point though - at some point we're going to need to work out which
> link in the driver corresponds to which link in the firmware file.

There is a 'version' field in struct snd_soc_tplg_hdr, which is a vendor-specific version number.
The driver can check this field of a firmware topology and decide whether to support this firmware or not.

Is this okay?

Thanks
Mengdong