Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 28 Apr 2020 13:21:45 +0530
From:   Vinod Koul <vkoul@kernel.org>
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Bard Liao <yung-chuan.liao@linux.intel.com>,
        alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org,
        tiwai@suse.de, broonie@kernel.org, jank@cadence.com,
        srinivas.kandagatla@linaro.org, rander.wang@linux.intel.com,
        ranjani.sridharan@linux.intel.com, hui.wang@canonical.com,
        pierre-louis.bossart@linux.intel.com, sanyog.r.kale@intel.com,
        slawomir.blauciak@intel.com, mengdong.lin@intel.com
Subject: Re: [RFC 1/5] soundwire: bus_type: add sdw_master_device support
Message-ID: <20200428075145.GB56386@vkoul-mobl.Dlink>
References: <20200416205524.2043-1-yung-chuan.liao@linux.intel.com>
 <20200416205524.2043-2-yung-chuan.liao@linux.intel.com>
 <20200420072631.GW72691@vkoul-mobl>
 <20200423142451.GA4181720@kroah.com>
 <20200428043144.GU56386@vkoul-mobl.Dlink>
 <20200428063736.GB990431@kroah.com>
 <20200428064951.GA56386@vkoul-mobl.Dlink>
 <20200428065524.GA992087@kroah.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200428065524.GA992087@kroah.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 28-04-20, 08:55, Greg KH wrote:
> On Tue, Apr 28, 2020 at 12:19:51PM +0530, Vinod Koul wrote:
> > On 28-04-20, 08:37, Greg KH wrote:
> > > On Tue, Apr 28, 2020 at 10:01:44AM +0530, Vinod Koul wrote:
> > > > > > That is not true for everyone, it is only true for Intel, pls call that
> > > > > > out as well...
> > > > > 
> > > > > Why is it not true for everyone?  How else do you get the pm stuff back
> > > > > to your hardware?
> > > > 
> > > > The rest of the world would do using the real controller device. For
> > > > example the soundwire controller on Qualcomm devices is enumerated as a
> > > > DT device and is using these...
> > > > 
> > > > If Intel had a standalone controller or enumerated as individual
> > > > functions, it would have been a PCI device and would manage as such
> > > 
> > > If it is not a standalone controller, what exactly is it?  I thought it
> > > was an acpi device, am I mistaken?
> > > 
> > > What is the device that the proper soundwire controller driver binds to
> > > on an Intel-based system?
> > 
> > The HDA controller which is a PCI device. The device represent HDA
> > function, DSP and Soundwire controller instances (yes it is typically
> > more than one instance)
> 
> Then those "instances" should be split up into individual devices that a
> driver can bind to.  See the work happening on the "virtual" bus for
> examples of how that can be done.

Yes removing platform devices is the goal for Intel now :) Pierre & Bard
have been diligently trying to solve this.

Only difference is the means to end goal. I am not convinced that this
should be in soundwire subsystem.

Looks like folks are trying to review and port to use this bus. Makes
sense to me..
https://lore.kernel.org/netdev/c5197d2f-3840-d304-6b09-d334cae81294@linux.intel.com/

> A platform device better not be being used here, I'm afraid to look at
> the code now...

Well if the plan for 'virtual-bus' goes well, it should be  a simple
replacement of platform->virtual for Intel driver. Rest of the driver
should not be impacted :)

Thanks
-- 
~Vinod