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Date:   Tue, 12 May 2020 09:00:35 +0530
From:   Vinod Koul <vkoul@kernel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Cc:     Bard Liao <yung-chuan.liao@linux.intel.com>,
        alsa-devel@alsa-project.org, tiwai@suse.de,
        gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
        ranjani.sridharan@linux.intel.com, hui.wang@canonical.com,
        broonie@kernel.org, srinivas.kandagatla@linaro.org,
        jank@cadence.com, mengdong.lin@intel.com,
        slawomir.blauciak@intel.com, sanyog.r.kale@intel.com,
        rander.wang@linux.intel.com, bard.liao@intel.com
Subject: Re: [PATCH 3/3] soundwire: bus_type: add sdw_master_device support
Message-ID: <20200512033035.GV1375924@vkoul-mobl>
References: <20200429185145.12891-1-yung-chuan.liao@linux.intel.com>
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 <20200511063227.GS1375924@vkoul-mobl>
 <e214d308-1b92-a7a5-3c76-da05dca99cc5@linux.intel.com>
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On 11-05-20, 14:00, Pierre-Louis Bossart wrote:
> > > +	md = &bus->md;
> > > +	md->dev.bus = &sdw_bus_type;
> > > +	md->dev.type = &sdw_master_type;
> > > +	md->dev.parent = parent;
> > > +	md->dev.of_node = parent->of_node;
> > > +	md->dev.fwnode = fwnode;
> > > +	md->dev.dma_mask = parent->dma_mask;
> > > +
> > > +	dev_set_name(&md->dev, "sdw-master-%d", bus->link_id);
> > 
> > This give nice sdw-master-0. In DT this comes from reg property. I dont
> > seem to recall if the ACPI/Disco spec treats link_id as unique across
> > the system, can you check that please, if not we would need to update
> > this.
> Table 3 in the Disco for Soundwire 1.0 spec: "all LinkID values are relative
> to the immediate parent Device."
> 
> There isn't any known implementation with more than one controller.

But then it can come in "future" right. So lets try to make it future
proof by not using the link_id (we can expose that as a sysfs if people
want to know). So a global unique id needs to allocated (hint: idr or
equivalent) and used as master_id

Thanks
-- 
~Vinod