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

From: Andrzej Hajda
Date: Fri Oct 30 2015 - 08:52:14 EST


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)



> + 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 :)

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);
>

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