From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH 1/3] [media] mt9v032: Add reset and standby gpios Date: Mon, 09 Nov 2015 14:28:56 +0200 Message-ID: <1763974.WDKlRvPG0G@avalon> References: <1446815625-18413-1-git-send-email-mpa@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1446815625-18413-1-git-send-email-mpa@pengutronix.de> Sender: linux-media-owner@vger.kernel.org To: Markus Pargmann Cc: Hans Verkuil , Philipp Zabel , devicetree@vger.kernel.org, linux-media@vger.kernel.org List-Id: devicetree@vger.kernel.org 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(). >=20 > 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 sho= uld=20 eventually get used, and given that specifying it in DT is a good hardw= are=20 description, that looks good to me. > Signed-off-by: Markus Pargmann > Reviewed-by: Philipp Zabel > --- > .../devicetree/bindings/media/i2c/mt9v032.txt | 2 ++ > drivers/media/i2c/mt9v032.c | 23 ++++++++++++= +++++++ > 2 files changed, 25 insertions(+) >=20 > 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: >=20 > - link-frequencies: List of allowed link frequencies in Hz. Each fre= quency > is expressed as a 64-bit big-endian integer. > +- reset-gpios: GPIO handle which is connected to the reset pin of th= e chip. > +- standby-gpios: GPIO handle which is connected to the standby pin o= f the > chip. >=20 > 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 > #include > #include > +#include module.h escaped my vigilance, but let's try to keep headers alphabetic= ally=20 sorted. >=20 > #include > #include > @@ -251,6 +252,8 @@ struct mt9v032 { >=20 > struct regmap *regmap; > struct clk *clk; > + struct gpio_desc *reset_gpio; > + struct gpio_desc *standby_gpio; >=20 > struct mt9v032_platform_data *pdata; > const struct mt9v032_model_info *model; > @@ -312,16 +315,26 @@ static int mt9v032_power_on(struct mt9v032 *mt9= v032) > struct regmap *map =3D mt9v032->regmap; > int ret; >=20 > + gpiod_set_value_cansleep(mt9v032->reset_gpio, 1); > + > ret =3D clk_set_rate(mt9v032->clk, mt9v032->sysclk); > if (ret < 0) > return ret; >=20 > + /* system clock has to be enabled before releasing the reset */ Nitpicking, the driver capitalizes the first letter of comments. > ret =3D clk_prepare_enable(mt9v032->clk); > if (ret) > return ret; >=20 > udelay(1); >=20 > + gpiod_set_value_cansleep(mt9v032->reset_gpio, 0); > + > + /* > + * After releasing reset, it can take up to 1us until the chip is d= one > + */ > + 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. 1=B5s = should be=20 safe as the minimum SYSCLK frequency is 13 MHz. I'd still mention it in= a=20 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 1=B5s 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=20 fix it when applying it to my tree. > /* Reset the chip and stop data read out */ > ret =3D regmap_write(map, MT9V032_RESET, 1); > if (ret < 0) > @@ -954,6 +967,16 @@ static int mt9v032_probe(struct i2c_client *clie= nt, > if (IS_ERR(mt9v032->clk)) > return PTR_ERR(mt9v032->clk); >=20 > + mt9v032->reset_gpio =3D devm_gpiod_get_optional(&client->dev, "rese= t", > + GPIOD_OUT_HIGH); > + if (IS_ERR(mt9v032->reset_gpio)) > + return PTR_ERR(mt9v032->reset_gpio); > + > + mt9v032->standby_gpio =3D devm_gpiod_get_optional(&client->dev, "st= andby", > + GPIOD_OUT_LOW); > + if (IS_ERR(mt9v032->standby_gpio)) > + return PTR_ERR(mt9v032->standby_gpio); > + > mutex_init(&mt9v032->power_lock); > mt9v032->pdata =3D pdata; > mt9v032->model =3D (const void *)did->driver_data; --=20 Regards, Laurent Pinchart