Re: [alsa-devel] [Patch v6 1/7] slimbus: Device management on SLIMbus

[Srinivas Kandagatla]

On 11/10/17 05:07, Vinod Koul wrote:
> On Tue, Oct 10, 2017 at 06:21:34PM +0100, Srinivas Kandagatla wrote:
> > On 10/10/17 17:49, Vinod Koul wrote:
>
> > > > > > +static int slim_device_probe(struct device *dev)
> > > > > > +{
> > > > > > +	struct slim_device	*sbdev;
> > > > > > +	struct slim_driver	*sbdrv;
> > > > > > +	int status = 0;
> > > > > > +
> > > > > > +	sbdev = to_slim_device(dev);
> > > > > > +	sbdrv = to_slim_driver(dev->driver);
> > > > > > +
> > > > > > +	sbdev->driver = sbdrv;
> > > > > > +
> > > > > > +	if (sbdrv->probe)
> > > > > > +		status = sbdrv->probe(sbdev);
> > > > > > +
> > > > > > +	if (status)
> > > > > > +		sbdev->driver = NULL;
> > > > > > +	else if (sbdrv->device_up)
> > > > > > +		schedule_slim_report(sbdev->ctrl, sbdev, true);
> > > > >
> > > > > can you please explain what this is trying to do?
> > > >
> > > > It is scheduling a device_up() callback in workqueue for reporting
> > > > discovered device.
> > >
> > > any reason for that? Would the device not announce itself on the bus and
> > > then you can synchronously update the device.
> > You are correct,  Device should announce itself in all cases. core should
> > only call this callback only when device is announced, it does not make
> > sense for this call in slim_device_probe(). Will remove it from here in next
> > version.
>
> Okay great. Btw do you need a notify being scheduled in those cases? I guess
> your controller would get an interrupt and you will handle that in bottom
> half and then cll this, so why not call in the bottom half?
That makes sense, I will optimize this path, It looks like there are 2 
workqueues in this path. We should be able to get rid of one work-queue.



> > > > > > +/**
> > > > > > + * slim_register_controller: Controller bring-up and registration.
> > ...
> > > > > > +
> > > > > > +	mutex_init(&ctrl->m_ctrl);
> > > > > > +	ret = device_register(&ctrl->dev);
> > > > >
> > > > > one more device_register?? Can you explain why
> > > >
> > > > This is a device for each controller.
> > >
> > > wont the controller have its own platform_device?
> >
> > Reason could be that slim_register controller can be called from any code
> > not just platform devices..
>
> ah which cases would those be. I was expecting that you would have a
> platform_device as a slimbus controller which would call slim_register?
As of now there is only one controller which uses platform driver, but 
in future there might be more, but this is something which makes the 
slimbus core more flexible.


>