linux-kernel - Re: [alsa-devel] [PATCH v5 09/17] soundwire: intel: remove platform devices and use 'Master Devices' instead

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Message-ID: <6635bf0b-c20a-7561-bcbf-4a480a077ae4@linux.intel.com>
Date:   Tue, 14 Jan 2020 10:01:04 -0600
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        tiwai@...e.de, broonie@...nel.org, gregkh@...uxfoundation.org,
        jank@...ence.com, srinivas.kandagatla@...aro.org,
        slawomir.blauciak@...el.com,
        Bard liao <yung-chuan.liao@...ux.intel.com>,
        Rander Wang <rander.wang@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>
Subject: Re: [alsa-devel] [PATCH v5 09/17] soundwire: intel: remove platform
 devices and use 'Master Devices' instead


> I am quoting the code in patch, which i pointed in my first reply!
> 
> On 17-12-19, 15:03, Pierre-Louis Bossart wrote:
> 
>> diff --git a/drivers/soundwire/intel_init.c b/drivers/soundwire/intel_init.c
>> index 4b769409f6f8..42f7ae034bea 100644
>> --- a/drivers/soundwire/intel_init.c
> 
> This is intel specific file...
> 
>> +++ b/drivers/soundwire/intel_init.c
> 
> snip ...
> 
>> +static struct sdw_intel_ctx
>> +*sdw_intel_probe_controller(struct sdw_intel_res *res)
> 
> this is intel driver, intel function!
> 
>> -
>> -		link->pdev = pdev;
>> -		link++;
>> +		/* let the SoundWire master driver to its probe */
>> +		md->driver->probe(md, link);
>                              ^^^^^^
> which does this... calls a probe()!
> 
> And my first reply was:
> 
>>> +             /* let the SoundWire master driver to its probe */
>>> +             md->driver->probe(md, link);
>>
>> So you are invoking driver probe here.. That is typically role of driver
>> core to do that.. If we need that, make driver core do that for you!
> 
> I rest my case!

I think you are too focused on the probe case and not realizing the 
extensions suggested by this patchset. A "driver" is not limited to 
'probe' and 'remove' cases.

As mentioned since mid-September, there is a need for an initialization 
of software/kernel structures (which I called probe but should have been 
called init really), and a second step where the hardware is actually 
configured - after all power rail dependencies are under control.

Can you please look at the .startup callback and let me know how a 
'driver core' would handle this?

To the best of my knowledge, there is no .startup in any device model 
functionality, so the only thing I could do to avoid a direct call is 
add a wrapper to avoid a direct call, e.g.

static inline sdw_master_device_startup(struct sdw_master_device *md)
{
     if (md && md->driver && md->driver->startup)
         md->driver->startup(md);
}