linux-kernel - Re: [PATCH 4/7] soundwire: intel: add definitions for shim

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Date:   Fri, 20 Mar 2020 09:13:03 -0500
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>,
        Hui Wang <hui.wang@...onical.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>
Subject: Re: [PATCH 4/7] soundwire: intel: add definitions for shim_mask


>> diff --git a/drivers/soundwire/intel.h b/drivers/soundwire/intel.h
>> index 568c84a80d79..cfc83120b8f9 100644
>> --- a/drivers/soundwire/intel.h
>> +++ b/drivers/soundwire/intel.h
>> @@ -16,6 +16,7 @@
>>    * @ops: Shim callback ops
>>    * @dev: device implementing hw_params and free callbacks
>>    * @shim_lock: mutex to handle access to shared SHIM registers
>> + * @shim_mask: global pointer to check SHIM register initialization
>>    */
>>   struct sdw_intel_link_res {
>>   	struct platform_device *pdev;
>> @@ -27,6 +28,7 @@ struct sdw_intel_link_res {
>>   	const struct sdw_intel_ops *ops;
>>   	struct device *dev;
>>   	struct mutex *shim_lock; /* protect shared registers */
>> +	u32 *shim_mask;
> 
> You have a pointer, okay where is it initialized

same answer as shim_lock, it's initialized at the higher level

https://github.com/thesofproject/linux/blob/9c7487b33072040ab755d32ca173b75151c0160c/drivers/soundwire/intel_init.c#L252


>>   };
>>   
>>   #endif /* __SDW_INTEL_LOCAL_H */
>> diff --git a/include/linux/soundwire/sdw_intel.h b/include/linux/soundwire/sdw_intel.h
>> index 979b41b5dcb4..120ffddc03d2 100644
>> --- a/include/linux/soundwire/sdw_intel.h
>> +++ b/include/linux/soundwire/sdw_intel.h
>> @@ -115,6 +115,7 @@ struct sdw_intel_slave_id {
>>    * links
>>    * @link_list: list to handle interrupts across all links
>>    * @shim_lock: mutex to handle concurrent rmw access to shared SHIM registers.
>> + * @shim_mask: flags to track initialization of SHIM shared registers
>>    */
>>   struct sdw_intel_ctx {
>>   	int count;
>> @@ -126,6 +127,7 @@ struct sdw_intel_ctx {
>>   	struct sdw_intel_slave_id *ids;
>>   	struct list_head link_list;
>>   	struct mutex shim_lock; /* lock for access to shared SHIM registers */
>> +	u32 shim_mask;
> 
> And a integer, question: why do you need pointer and integer, why not
> use only one..?

You may have missed that the structures are different.

the sdw_intel_ctx is global for all links, so that the shim_mask integer 
value.
the sdw_intel_link_res is link-specific and use a pointer to the same 
shim_mask value, protected by shim_lock.