Hi,
On Monday 09 November 2015 14:28:56 Laurent Pinchart wrote:
> Hi Markus,
>
> Thank you for the patch.
>
> On Friday 06 November 2015 14:13:43 Markus Pargmann wrote:
> > Add optional reset and standby gpios. The reset gpio is used to reset
> > the chip in power_on().
> >
> > The standby gpio is not used currently. It is just unset, so the chip is
> > not in standby.
>
> We could use a gpio hog for this, but given that the standby signal should
> eventually get used, and given that specifying it in DT is a good hardware
> description, that looks good to me.
>
> > Signed-off-by: Markus Pargmann <mpa@xxxxxxxxxxxxxx>
> > Reviewed-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> > ---
> > .../devicetree/bindings/media/i2c/mt9v032.txt | 2 ++
> > drivers/media/i2c/mt9v032.c | 23 +++++++++++++++++++
> > 2 files changed, 25 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/media/i2c/mt9v032.txt
> > b/Documentation/devicetree/bindings/media/i2c/mt9v032.txt index
> > 202565313e82..100f0ae43269 100644
> > --- a/Documentation/devicetree/bindings/media/i2c/mt9v032.txt
> > +++ b/Documentation/devicetree/bindings/media/i2c/mt9v032.txt
> > @@ -20,6 +20,8 @@ Optional Properties:
> >
> > - link-frequencies: List of allowed link frequencies in Hz. Each frequency
> > is expressed as a 64-bit big-endian integer.
> > +- reset-gpios: GPIO handle which is connected to the reset pin of the chip.
> > +- standby-gpios: GPIO handle which is connected to the standby pin of the
> > chip.
> >
> > For further reading on port node refer to
> > Documentation/devicetree/bindings/media/video-interfaces.txt.
> > diff --git a/drivers/media/i2c/mt9v032.c b/drivers/media/i2c/mt9v032.c
> > index a68ce94ee097..4aefde9634f5 100644
> > --- a/drivers/media/i2c/mt9v032.c
> > +++ b/drivers/media/i2c/mt9v032.c
> > @@ -24,6 +24,7 @@
> > #include <linux/videodev2.h>
> > #include <linux/v4l2-mediabus.h>
> > #include <linux/module.h>
> > +#include <linux/gpio/consumer.h>
>
> module.h escaped my vigilance, but let's try to keep headers alphabetically
> sorted.
> >
> > #include <media/mt9v032.h>
> > #include <media/v4l2-ctrls.h>
> > @@ -251,6 +252,8 @@ struct mt9v032 {
> >
> > struct regmap *regmap;
> > struct clk *clk;
> > + struct gpio_desc *reset_gpio;
> > + struct gpio_desc *standby_gpio;
> >
> > struct mt9v032_platform_data *pdata;
> > const struct mt9v032_model_info *model;
> > @@ -312,16 +315,26 @@ static int mt9v032_power_on(struct mt9v032 *mt9v032)
> > struct regmap *map = mt9v032->regmap;
> > int ret;
> >
> > + gpiod_set_value_cansleep(mt9v032->reset_gpio, 1);
> > +
> > ret = clk_set_rate(mt9v032->clk, mt9v032->sysclk);
> > if (ret < 0)
> > return ret;
> >
> > + /* system clock has to be enabled before releasing the reset */
>
> Nitpicking, the driver capitalizes the first letter of comments.
>
> > ret = clk_prepare_enable(mt9v032->clk);
> > if (ret)
> > return ret;
> >
> > udelay(1);
> >
> > + gpiod_set_value_cansleep(mt9v032->reset_gpio, 0);
> > +
> > + /*
> > + * After releasing reset, it can take up to 1us until the chip is done
> > + */
> > + udelay(1);
> > +
>
> The delay isn't necessary if there's no reset GPIO. How about
>
> if (mt9v032->reset_gpio) {
> gpiod_set_value_cansleep(mt9v032->reset_gpio, 0);
>
> /* After releasing reset, it can take up to 1us until the
> * chip is done.
> */
> udelay(1);
> }
>
> And, according to the datasheet, the delay is 10 SYSCLK periods. 1µs should be
> safe as the minimum SYSCLK frequency is 13 MHz. I'd still mention it in a
> comment, maybe as
>
> /* After releasing reset we need to wait 10 clock cycles
> * before accessing the sensor over I2C. As the minimum SYSCLK
> * frequency is 13MHz, waiting 1µs will be enough in the worst
> * case.
> */
> udelay(1);
>
> If you're fine with these changes there's no need to resubmit the patch, I can
> fix it when applying it to my tree.
Thanks, I am fine with all your changes. But as there will be a v2 for the
other two patches I could as well send an updated version if you wish.
Thanks,
Markus
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