linux-kernel - Re: [PATCH] soundwire: debugfs: use controller id instead of link

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Message-ID: <feee8676-33fe-7929-8b6c-6abe3a09159a@linaro.org>
Date:   Thu, 21 Jan 2021 17:23:15 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Vinod Koul <vkoul@...nel.org>
Cc:     gregkh@...uxfoundation.org, alsa-devel@...a-project.org,
        yung-chuan.liao@...ux.intel.com, linux-kernel@...r.kernel.org,
        sanyog.r.kale@...el.com
Subject: Re: [PATCH] soundwire: debugfs: use controller id instead of link_id



On 21/01/2021 15:12, Pierre-Louis Bossart wrote:
> 
> 
> On 1/21/21 6:03 AM, Srinivas Kandagatla wrote:
>>
>>
>> On 19/01/2021 19:09, Pierre-Louis Bossart wrote:
>>>
>>>> currently we have
>>>> /sys/kernel/debug/soundwire/master-*
>>>>
>>>> Are you suggesting that we have something like this:
>>>>
>>>> /sys/kernel/debug/soundwire/xyz-controller/master-<LINK-ID> ??
>>>
>>> Yes this is what I was thinking about.
>>
>> Vinod/Pierre,
>>
>> One Question here,
>>
>> Why is link_id part of "struct sdw_bus", should it not be part of 
>> "struct sdw_master_device " ?
>>
>> Given that "There is one Link per each Master"
> 
> it's true that link == master == bus at the concept level.
> 
> but we have an existing code base with different structures and we can't 
> break too many things at once.
> 
> In the existing flow, the 'bus' is created and setup first, the 
> sdw_bus_master_add() routine takes a 'bus' argument, and the link_id is 
> already set. This routine only creates a device and in the rest of the 
> code we keep using the 'bus' pointer, so there's no real short-term 
> scope for moving the information into the 'sdw_master_device' structure 
> - that would be a lot of surgery when nothing is really broken.

I totally agree!

If I understand it correctly in Intel case there will be only one Link 
ID per bus.


Does this change look good to you?

---------------->cut<---------------

diff --git a/drivers/soundwire/debugfs.c b/drivers/soundwire/debugfs.c
index b6cad0d59b7b..f22868614f09 100644
--- a/drivers/soundwire/debugfs.c
+++ b/drivers/soundwire/debugfs.c
@@ -19,13 +19,14 @@ void sdw_bus_debugfs_init(struct sdw_bus *bus)
                 return;

         /* create the debugfs master-N */
+       bus->controller_debugfs = debugfs_create_dir(dev_name(bus->dev), 
sdw_debugfs_root);
         snprintf(name, sizeof(name), "master-%d", bus->link_id);
-       bus->debugfs = debugfs_create_dir(name, sdw_debugfs_root);
+       bus->debugfs = debugfs_create_dir(name, bus->controller_debugfs);
  }

  void sdw_bus_debugfs_exit(struct sdw_bus *bus)
  {
-       debugfs_remove_recursive(bus->debugfs);
+       debugfs_remove_recursive(bus->controller_debugfs);
  }

  #define RD_BUF (3 * PAGE_SIZE)
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index b198f471bea8..242bde30d8bd 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -877,6 +877,7 @@ struct sdw_bus {
         struct sdw_master_prop prop;
         struct list_head m_rt_list;
  #ifdef CONFIG_DEBUG_FS
+       struct dentry *controller_debugfs;
         struct dentry *debugfs;
  #endif
         struct sdw_defer defer_msg;

---------------->cut<---------------

With this change I get something like this on my board:

~# find /sys/kernel/debug/soundwire/
/sys/kernel/debug/soundwire/
/sys/kernel/debug/soundwire/sdw-master-2
/sys/kernel/debug/soundwire/sdw-master-2/master-0
/sys/kernel/debug/soundwire/sdw-master-2/master-0/sdw:0:217:2110:0:4
/sys/kernel/debug/soundwire/sdw-master-2/master-0/sdw:0:217:2110:0:4/registers
/sys/kernel/debug/soundwire/sdw-master-2/master-0/sdw:0:217:2110:0:3
/sys/kernel/debug/soundwire/sdw-master-2/master-0/sdw:0:217:2110:0:3/registers
/sys/kernel/debug/soundwire/sdw-master-1
/sys/kernel/debug/soundwire/sdw-master-1/master-0
/sys/kernel/debug/soundwire/sdw-master-1/master-0/sdw:0:217:10d:0:3
/sys/kernel/debug/soundwire/sdw-master-1/master-0/sdw:0:217:10d:0:3/registers
/sys/kernel/debug/soundwire/sdw-master-0
/sys/kernel/debug/soundwire/sdw-master-0/master-0
/sys/kernel/debug/soundwire/sdw-master-0/master-0/sdw:0:217:10d:0:4
/sys/kernel/debug/soundwire/sdw-master-0/master-0/sdw:0:217:10d:0:4/registers



Thanks,
srini