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Subject: Re: [alsa-devel] [RFC PATCH 4/5] ASoC: SOF: Intel: hda: add SoundWire
 stream config/free callbacks
To:     Vinod Koul <vkoul@kernel.org>
Cc:     Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>,
        alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org,
        tiwai@suse.de, broonie@kernel.org, gregkh@linuxfoundation.org,
        jank@cadence.com, srinivas.kandagatla@linaro.org,
        slawomir.blauciak@intel.com,
        Bard liao <yung-chuan.liao@linux.intel.com>,
        Rander Wang <rander.wang@linux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@linux.intel.com>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Jaroslav Kysela <perex@perex.cz>,
        Takashi Iwai <tiwai@suse.com>,
        Zhu Yingjiang <yingjiang.zhu@linux.intel.com>,
        YueHaibing <yuehaibing@huawei.com>,
        Kai Vehmanen <kai.vehmanen@linux.intel.com>,
        Arnd Bergmann <arnd@arndb.de>
References: <20190821201720.17768-1-pierre-louis.bossart@linux.intel.com>
 <20190821201720.17768-5-pierre-louis.bossart@linux.intel.com>
 <20190822071835.GA30262@ubuntu>
 <f73796d6-fcfa-97c8-69ae-0a183edbbd97@linux.intel.com>
 <20190904073549.GL2672@vkoul-mobl>
From:   Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Message-ID: <4de9613c-2da4-8d39-6f99-3039811673b8@linux.intel.com>
Date:   Wed, 4 Sep 2019 08:31:42 -0500
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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.