Re: [alsa-devel] [RFC PATCH 4/5] ASoC: SOF: Intel: hda: add SoundWire stream config/free callbacks

From: Pierre-Louis Bossart
Date: Wed Sep 04 2019 - 09:31:47 EST

On 9/4/19 2:35 AM, Vinod Koul wrote:
On 22-08-19, 08:53, Pierre-Louis Bossart wrote:
Thanks for the review Guennadi

+static int sdw_config_stream(void *arg, void *s, void *dai,
+ void *params, int link_id, int alh_stream_id)

I realise, that these function prototypes aren't being introduced by these
patches, but just wondering whether such overly generic prototype is really
a good idea here, whether some of those "void *" pointers could be given
real types. The first one could be "struct device *" etc.

In this case the 'arg' parameter is actually a private 'struct snd_sof_dev',
as shown below [1]. We probably want to keep this relatively opaque, this is
a context that doesn't need to be exposed to the SoundWire code.

This does look bit ugly.

The dai and params are indeed cases where we could use stronger types, they
are snd_soc_dai and hw_params respectively. I don't recall why the existing
code is this way, Vinod and Sanyog may have the history of this.

Yes we wanted to decouple the sdw and audio bits that is the reason why
none of the audio types are used here, but I think it should be revisited
and perhaps made as:

sdw_config_stream(struct device *sdw, struct sdw_callback_ctx *ctx)

where the callback context contains all the other args. That would make
it look lot neater too and of course use real structs if possible

the suggested sdw_callbback_ctx is really intel-specific at the moment, e.g. the notion of link_id and alh_stream_id are due to the hardware, it's not generic at all. And in the latest code we also pass the dai->id.