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

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Date:   Mon, 1 Feb 2021 15:44:14 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        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 21-01-21, 17:23, Srinivas Kandagatla wrote:
> 
> 
> 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.

Yes IIUC there would be one link id per bus.

the ida approach gives us unique id for each master,bus I would like to
propose using that everywhere

> 
> 
> 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

-- 
~Vinod