From mboxrd@z Thu Jan  1 00:00:00 1970
From: Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v7 04/13] slimbus: core: Add slim controllers support
Date: Fri, 17 Nov 2017 09:13:22 +0100
Message-ID: <20171117081322.GF10671@kroah.com>
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To: Vinod Koul <vinod.koul@intel.com>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>, broonie@kernel.org, alsa-devel@alsa-project.org, sdharia@codeaurora.org, bp@suse.de, poeschel@lemonage.de, treding@nvidia.com, andreas.noever@gmail.com, alan@linux.intel.com, mathieu.poirier@linaro.org, daniel@ffwll.ch, jkosina@suse.cz, sharon.dvir1@mail.huji.ac.il, joe@perches.com, davem@davemloft.net, james.hogan@imgtec.com, michael.opdenacker@free-electrons.com, robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, arnd@arndb.de
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On Fri, Nov 17, 2017 at 10:12:22AM +0530, Vinod Koul wrote:
> On Thu, Nov 16, 2017 at 05:29:35PM +0000, Srinivas Kandagatla wrote:
> > thanks for the comments.
> > 
> > 
> > On 16/11/17 16:42, Vinod Koul wrote:
> > >On Wed, Nov 15, 2017 at 02:10:34PM +0000, srinivas.kandagatla@linaro.org wrote:
> > >
> > >>+static void slim_dev_release(struct device *dev)
> > >>+{
> > >>+	struct slim_device *sbdev = to_slim_device(dev);
> > >>+
> > >>+	put_device(sbdev->ctrl->dev);
> > >
> > >which device would that be?
> > This is controller device
> > 
> > >
> > >>+static int slim_add_device(struct slim_controller *ctrl,
> > >>+			   struct slim_device *sbdev,
> > >>+			   struct device_node *node)
> > >>+{
> > >>+	sbdev->dev.bus = &slimbus_bus;
> > >>+	sbdev->dev.parent = ctrl->dev;
> > >>+	sbdev->dev.release = slim_dev_release;
> > >>+	sbdev->dev.driver = NULL;
> > >>+	sbdev->ctrl = ctrl;
> > >>+
> > >>+	dev_set_name(&sbdev->dev, "%x:%x:%x:%x",
> > >>+				  sbdev->e_addr.manf_id,
> > >>+				  sbdev->e_addr.prod_code,
> > >>+				  sbdev->e_addr.dev_index,
> > >>+				  sbdev->e_addr.instance);
> > >>+
> > >>+	get_device(ctrl->dev);
> > >
> > >is this controller device and you ensuring it doesnt go away while you have
> > >slaves on it?
> > 
> > Yes.
> 
> I thought since you are marking ctrl->dev as parent, the device core should
> ensure that parent doesn't go off when you have child device?
> 
> Greg, is that understanding correct, if so we may not need these calls.

That understanding should be correct, as the reference count is
incremented on the parent when a child is added.

It would be trivial for this to be tested, and yes, I am pretty sure you
don't need this call.

thanks,

greg k-h