Re: [RFC v2 3/5] drm/dsi: Check for used channels

[Archit Taneja]

On 10/30/2015 06:22 PM, Andrzej Hajda wrote:
> On 10/06/2015 11:24 AM, Archit Taneja wrote:
> > We don't check whether a previously registered mipi_dsi_device under the
> > same host shares the same virtual channel.
> >
> > Before registering, check if any of the registered devices doesn't
> > already have the same virtual channel.
> >
> > This wasn't crucial when all the devices under a host were populated via
> > DT. Now that we also support creating devices manually, we could end up
> > in a situation where a driver tries to create a device with a virtual
> > channel already taken by a device populated in DT.
> >
> > Signed-off-by: Archit Taneja <architt@xxxxxxxxxxxxxx>
> Beside few non-blcking nitpicks.
>
> Reviewed-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
>
> > ---
> >   drivers/gpu/drm/drm_mipi_dsi.c | 26 ++++++++++++++++++++++++--
> >   1 file changed, 24 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> > index 46ee515..db6130a 100644
> > --- a/drivers/gpu/drm/drm_mipi_dsi.c
> > +++ b/drivers/gpu/drm/drm_mipi_dsi.c
> > @@ -123,6 +123,22 @@ static const struct device_type mipi_dsi_device_type = {
> >   	.release = mipi_dsi_dev_release,
> >   };
> >
> > +static int __dsi_check_chan_busy(struct device *dev, void *data)
> > +{
> > +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev);
> > +	u32 reg = *(u32 *) data;
> > +
> > +	if (dsi && dsi->channel == reg)
> Maybe simpler would be:
>
>      u32 *reg = data;
>
>      if (dsi && dsi->channel == *reg)

This is better. I'll change it to this.

> > +		return -EBUSY;
> > +
> > +	return 0;
> > +}
> > +
> > +static int mipi_dsi_check_chan_busy(struct mipi_dsi_host *host, u32 reg)
> > +{
> > +	return device_for_each_child(host->dev, &reg, __dsi_check_chan_busy);
> > +}
> > +
> >   struct mipi_dsi_device *mipi_dsi_device_new(struct mipi_dsi_host *host,
> >   					    struct mipi_dsi_device_info *info)
> >   {
> > @@ -150,14 +166,20 @@ struct mipi_dsi_device *mipi_dsi_device_new(struct mipi_dsi_host *host,
> >
> >   	dev_set_name(&dsi->dev, "%s.%d", dev_name(host->dev), info->reg);
> >
> > +	r = mipi_dsi_check_chan_busy(host, info->reg);
>
> I know this r variable was introduced in the 1st patch, but if you will send
> next iteration
> consider replacing it with ret, looks more readable and follows file convention :)

I'll probably end up sending another iteration (or more). I'll change
the name.

Thanks,
Archit

> Regards
> Andrzej
>
> > +	if (r)
> > +		goto err;
> > +
> >   	r = device_register(&dsi->dev);
> >   	if (r) {
> >   		dev_err(dev, "failed to register device: %d\n", r);
> > -		kfree(dsi);
> > -		return ERR_PTR(r);
> > +		goto err;
> >   	}
> >
> >   	return dsi;
> > +err:
> > +	kfree(dsi);
> > +	return ERR_PTR(r);
> >   }
> >   EXPORT_SYMBOL(mipi_dsi_device_new);
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
Forum, hosted by The Linux Foundation
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/