Re: [PATCH RFC v2] media: i2c: mt9p031: add OF support

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Prabhakar,

Thank you for the patch.

On Thursday 02 May 2013 12:34:25 Prabhakar Lad wrote:
> On Thu, May 2, 2013 at 12:25 PM, Sascha Hauer wrote:
> > On Thu, May 02, 2013 at 11:52:34AM +0530, Prabhakar Lad wrote:
> >> From: Lad, Prabhakar <prabhakar.csengg@gmail.com>
> >> 
> >> add OF support for the mt9p031 sensor driver.
> >> Alongside this patch sorts the header inclusion alphabetically.
> 
> [Snip]
> 
> >> +#if defined(CONFIG_OF)
> >> +static struct mt9p031_platform_data *
> >> +     mt9p031_get_pdata(struct i2c_client *client)

Please align this line on the left.

> >> +{
> >> +     if (client->dev.of_node) {
> > 
> > By inverting the logic here and returning immediately you can safe an
> > indention level for the bulk of this function.
> 
> OK
> 
> >> +             struct device_node *np;
> >> +             struct mt9p031_platform_data *pdata;
> >> +
> >> +             np = v4l2_of_get_next_endpoint(client->dev.of_node, NULL);
> >> +             if (!np)
> >> +                     return NULL;
> >> +
> >> +             pdata = devm_kzalloc(&client->dev,
> >> +                                  sizeof(struct mt9p031_platform_data),
> >> +                                  GFP_KERNEL);
> >> +             if (!pdata) {
> >> +                     dev_err(&client->dev,
> >> +                             "mt9p031 failed allocate memeory\n");
> >> +                     return NULL;
> > 
> > s/memeory/memory/
> > 
> > Better drop this message completely. If you are really out of memory
> > you'll notice it quite fast anyway.
> 
> alright I'll drop the message.
> 
> >> +             }
> >> +             pdata->reset = of_get_named_gpio(client->dev.of_node,
> >> +                                              "gpio-reset", 0);
> >> +             if (!gpio_is_valid(pdata->reset))
> >> +                     pdata->reset = -1;

I've just sent a patch that converts the manual -1 checks in the driver to 
gpio_is_valid(). You can thus drop these two lines.

> >> +             if (of_property_read_u32(np, "input-clock-frequency",
> >> +                                      &pdata->ext_freq))
> >> +                     return NULL;
> >> +
> >> +             if (of_property_read_u32(np, "pixel-clock-frequency",
> >> +                                      &pdata->target_freq))
> >> +                     return NULL;
> > 
> > returning NULL here means that when these properties are missing the
> > driver bails out with the message "No platform data\n" which is not
> > very helpful for users. How about just ignoring this here and return
> > pdata? The driver will probably print a more useful message later when
> > it notices that the clock params are invalid.
> 
> Yes would be good idea of not returning NULL.
> 
> >> +
> >> +             return pdata;
> >> +     }
> >> +
> >> +     return client->dev.platform_data;
> >> +}
> >> +#else
> >> +static struct mt9p031_platform_data *
> >> +     mt9p031_get_pdata(struct i2c_client *client)
> >> +{
> >> +     return client->dev.platform_data;
> >> +}
> >> +#endif
> >> +
> >> 
> >>  static int mt9p031_probe(struct i2c_client *client,
> >>                        const struct i2c_device_id *did)
> >>  {
> >> -     struct mt9p031_platform_data *pdata = client->dev.platform_data;
> >> +     struct mt9p031_platform_data *pdata = mt9p031_get_pdata(client);
> >> 
> >>       struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
> >>       struct mt9p031 *mt9p031;
> >>       unsigned int i;
> >> @@ -1070,8 +1120,16 @@ static const struct i2c_device_id mt9p031_id[] = {
> >> 
> >>  };
> >>  MODULE_DEVICE_TABLE(i2c, mt9p031_id);
> >> 
> >> +static const struct of_device_id mt9p031_of_match[] = {
> >> +     { .compatible = "aptina,mt9p031", },
> >> +     { .compatible = "aptina,mt9p031m", },
> >> +     {},
> >> +};
> > 
> > I would have expected something like:
> > 
> > static const struct of_device_id mt9p031_of_match[] = {
> >         {
> >                 .compatible = "aptina,mt9p031-sensor",
> >                 .data = (void *)MT9P031_MODEL_COLOR,
> >         }, {
> >                 .compatible = "aptina,mt9p031m-sensor",
> >                 .data = (void *)MT9P031_MODEL_MONOCHROME,
> >         }, {
> >                 /* sentinel */
> >         },
> > };
> > 
> >         of_id = of_match_device(mt9p031_of_match, &client->dev);
> >         if (of_id)
> >                 mt9p031->model = (enum mt9p031_model)of_id->data;
> > 
> > To handle monochrome sensors.
> 
> OK will do the same.

And please guard the table with #ifdef CONFIG_OF.

-- 
Regards,

Laurent Pinchart