Hi Javier,
Thankk you for the patch.
On Monday 04 January 2016 09:25:31 Javier Martinez Canillas wrote:
> After power-up, the tvp5150 decoder is in a unknown state until the
> RESETB pin is driven LOW which reset all the registers and restarts
> the chip's internal state machine.
>
> The init sequence has some timing constraints and the RESETB signal
> can only be used if the PDN (Power-down) pin is first released.
>
> So, the initialization sequence is as follows:
>
> 1- PDN (active-low) is driven HIGH so the chip is power-up
> 2- A 20 ms delay is needed before sending a RESETB (active-low) signal.
> 3- The RESETB pulse duration is 500 ns.
> 4- A 200 us delay is needed for the I2C client to be active after reset.
>
> This patch used as a reference the logic in the IGEPv2 board file from
> the ISEE 2.6.37 vendor tree.
>
> Signed-off-by: Javier Martinez Canillas <javier@xxxxxxxxxxxxxxx>
> ---
>
> drivers/media/i2c/tvp5150.c | 35 +++++++++++++++++++++++++++++++++++
> 1 file changed, 35 insertions(+)
>
> diff --git a/drivers/media/i2c/tvp5150.c b/drivers/media/i2c/tvp5150.c
> index caac96a577f8..fed89a811ab7 100644
> --- a/drivers/media/i2c/tvp5150.c
> +++ b/drivers/media/i2c/tvp5150.c
> @@ -5,6 +5,7 @@
> * This code is placed under the terms of the GNU General Public License v2
> */
>
> +#include <linux/of_gpio.h>
Let's keep the headers sorted alphabetically if you don't mind :-)
> #include <linux/i2c.h>
> #include <linux/slab.h>
> #include <linux/videodev2.h>
> @@ -1197,6 +1198,36 @@ static int tvp5150_detect_version(struct tvp5150
> *core) return 0;
> }
>
> +static inline int tvp5150_init(struct i2c_client *c)
> +{
> + struct gpio_desc *pdn_gpio;
> + struct gpio_desc *reset_gpio;
> +
> + pdn_gpio = devm_gpiod_get_optional(&c->dev, "powerdown", GPIOD_OUT_HIGH);
> + if (IS_ERR(pdn_gpio))
> + return PTR_ERR(pdn_gpio);
> +
> + if (pdn_gpio) {
> + gpiod_set_value_cansleep(pdn_gpio, 0);
> + /* Delay time between power supplies active and reset */
> + msleep(20);
How about usleep_range() instead ?
> + }
> +
> + reset_gpio = devm_gpiod_get_optional(&c->dev, "reset", GPIOD_OUT_HIGH);
> + if (IS_ERR(reset_gpio))
> + return PTR_ERR(reset_gpio);
> +
> + if (reset_gpio) {
> + /* RESETB pulse duration */
> + ndelay(500);
Is the timing so sensitive that we need a delay, or could we use
usleep_range() ?
> + gpiod_set_value_cansleep(reset_gpio, 0);
> + /* Delay time between end of reset to I2C active */
> + usleep_range(200, 250);
> + }
> +
> + return 0;
> +}
> +
> static int tvp5150_probe(struct i2c_client *c,
> const struct i2c_device_id *id)
> {
> @@ -1209,6 +1240,10 @@ static int tvp5150_probe(struct i2c_client *c,
> I2C_FUNC_SMBUS_READ_BYTE | I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
> return -EIO;
>
> + res = tvp5150_init(c);
> + if (res)
> + return res;
> +
> core = devm_kzalloc(&c->dev, sizeof(*core), GFP_KERNEL);
> if (!core)
> return -ENOMEM;
--
Regards,
Laurent Pinchart
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
