linux-kernel - Re: [PATCH 3/3] soundwire: bus: clear parity interrupt before the mask is enabled

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Date:   Mon, 1 Feb 2021 10:29:44 -0600
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Vinod Koul <vkoul@...nel.org>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, jank@...ence.com,
        srinivas.kandagatla@...aro.org, rander.wang@...ux.intel.com,
        ranjani.sridharan@...ux.intel.com, hui.wang@...onical.com,
        sanyog.r.kale@...el.com, bard.liao@...el.com
Subject: Re: [PATCH 3/3] soundwire: bus: clear parity interrupt before the
 mask is enabled


>>   	 * Set SCP_INT1_MASK register, typically bus clash and
>> diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
>> index f7ba1a77a1df..c1fdc85d0a74 100644
>> --- a/drivers/soundwire/intel.c
>> +++ b/drivers/soundwire/intel.c
>> @@ -1286,7 +1286,8 @@ static int sdw_master_read_intel_prop(struct sdw_bus *bus)
>>   	if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE)
>>   		prop->hw_disabled = true;
>>   
>> -	prop->quirks = SDW_MASTER_QUIRKS_CLEAR_INITIAL_CLASH;
>> +	prop->quirks = SDW_MASTER_QUIRKS_CLEAR_INITIAL_CLASH |
>> +		SDW_MASTER_QUIRKS_CLEAR_INITIAL_PARITY;
> 
> move this to intel patch please..
> 
>>   
>>   	return 0;
>>   }
>> diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
>> index a2766c3b603d..30415354d419 100644
>> --- a/include/linux/soundwire/sdw.h
>> +++ b/include/linux/soundwire/sdw.h
>> @@ -426,6 +426,7 @@ struct sdw_master_prop {
>>   };
>>   
>>   #define SDW_MASTER_QUIRKS_CLEAR_INITIAL_CLASH	BIT(0)
>> +#define SDW_MASTER_QUIRKS_CLEAR_INITIAL_PARITY	BIT(1)
> 
> Why not add this quirk in patch 1..?

There is an element of history here. We first found out about the bus 
clash on multiple devices and dealt with a specific bug number. Then we 
spend weeks on the parity issue on a new platform and ultimately showed 
we needed a similar work-around.

All these problems are not typical from a user perspective; they appear 
when loading/unloading modules in loops, at some point it seems some 
hardware devices don't always reset properly or there's something 
problematic in power delivery.

I don't think it's an issue if we refactor the code to add the quirks 
first, and add the intel.c patches later. We probably want 2 intel 
changes to keep the references to the bugs though and the detailed 
explanations.

> Also add comments about each quirk, hopefully it wont be a big table

Sounds fine.