Re: [v2 2/3] media: ov8856: Add devicetree support

Sakari Ailus
2020-03-13T12:18:52Z

Hi Robert,

On Fri, Mar 13, 2020 at 12:03:49PM +0100, Robert Foss wrote:
> Add devicetree match table, and enable ov8856_probe()
> to initialize power, clocks and reset pins.
>
> Signed-off-by: Robert Foss <robert.foss@linaro.org>
> ---
>
> - Changes since v1:
> * Fabio: Change n_shutdown_gpio name to reset_gpio
> * Fabio: Invert reset_gpio due to GPIO_ACTIVE_HIGH -> GPIO_ACTIVE_LOW change
> * Fabio: Remove empty line
> * Fabio: Remove real error from devm_gpiod_get() failures
> * Andy & Sakari: Make XVCLK optional since to not break ACPI
> * Sakari: ARRAY_SIZE() directly instead of through OV8856_NUM_SUPPLIES
> * Sakari: Use XVCLK rate as provided by DT
>
> drivers/media/i2c/ov8856.c | 109 ++++++++++++++++++++++++++++++++++++-
> 1 file changed, 107 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/i2c/ov8856.c b/drivers/media/i2c/ov8856.c
> index 8655842af275..db61eed223e8 100644
> --- a/drivers/media/i2c/ov8856.c
> +++ b/drivers/media/i2c/ov8856.c
> @@ -3,10 +3,13 @@
>
> #include <asm/unaligned.h>
> #include <linux/acpi.h>
> +#include <linux/clk.h>
> #include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> #include <linux/i2c.h>
> #include <linux/module.h>
> #include <linux/pm_runtime.h>
> +#include <linux/regulator/consumer.h>
> #include <media/v4l2-ctrls.h>
> #include <media/v4l2-device.h>
> #include <media/v4l2-fwnode.h>
> @@ -19,6 +22,8 @@
> #define OV8856_LINK_FREQ_180MHZ 180000000ULL
> #define OV8856_SCLK 144000000ULL
> #define OV8856_MCLK 19200000
> +#define OV8856_XVCLK_19_2 19200000

Please use a single macro to refer to 19,2 MHz clock.

> +#define OV8856_XVCLK_24 24000000

This doesn't seem to be needed

> #define OV8856_DATA_LANES 4
> #define OV8856_RGB_DEPTH 10
>
> @@ -64,6 +69,12 @@
>
> #define to_ov8856(_sd) container_of(_sd, struct ov8856, sd)
>
> +static const char * const ov8856_supply_names[] = {
> + "dovdd", /* Digital I/O power */
> + "avdd", /* Analog power */
> + "dvdd", /* Digital core power */
> +};
> +
> enum {
> OV8856_LINK_FREQ_720MBPS,
> OV8856_LINK_FREQ_360MBPS,
> @@ -566,6 +577,10 @@ struct ov8856 {
> struct media_pad pad;
> struct v4l2_ctrl_handler ctrl_handler;
>
> + struct clk *xvclk;
> + struct gpio_desc *reset_gpio;
> + struct regulator_bulk_data supplies[ARRAY_SIZE(ov8856_supply_names)];
> +
> /* V4L2 Controls */
> struct v4l2_ctrl *link_freq;
> struct v4l2_ctrl *pixel_rate;
> @@ -908,6 +923,46 @@ static int ov8856_set_stream(struct v4l2_subdev *sd, int enable)
> return ret;
> }
>
> +static int __ov8856_power_on(struct ov8856 *ov8856)
> +{
> + struct i2c_client *client = v4l2_get_subdevdata(&ov8856->sd);
> + int ret;
> +
> + ret = clk_prepare_enable(ov8856->xvclk);
> + if (ret < 0) {
> + dev_err(&client->dev, "failed to enable xvclk\n");
> + return ret;
> + }
> +
> + gpiod_set_value_cansleep(ov8856->reset_gpio, GPIOD_OUT_HIGH);
> +
> + ret = regulator_bulk_enable(ARRAY_SIZE(ov8856_supply_names),
> + ov8856->supplies);
> + if (ret < 0) {
> + dev_err(&client->dev, "failed to enable regulators\n");
> + goto disable_clk;
> + }
> +
> + gpiod_set_value_cansleep(ov8856->reset_gpio, GPIOD_OUT_LOW);
> +
> + usleep_range(1500, 1800);

I think you could omit the delay on ACPI based systems. Or just bail out
early in that case.

> +
> + return 0;
> +
> +disable_clk:

How about the GPIO here?

> + clk_disable_unprepare(ov8856->xvclk);
> +
> + return ret;
> +}
> +
> +static void __ov8856_power_off(struct ov8856 *ov8856)
> +{
> + gpiod_set_value_cansleep(ov8856->reset_gpio, GPIOD_OUT_HIGH);
> + regulator_bulk_disable(ARRAY_SIZE(ov8856_supply_names),
> + ov8856->supplies);
> + clk_disable_unprepare(ov8856->xvclk);
> +}

You'll need to call the two in the driver's suspend and resume functions.

> +
> static int __maybe_unused ov8856_suspend(struct device *dev)
> {
> struct i2c_client *client = to_i2c_client(dev);
> @@ -1175,7 +1230,7 @@ static int ov8856_remove(struct i2c_client *client)
> static int ov8856_probe(struct i2c_client *client)
> {
> struct ov8856 *ov8856;
> - int ret;
> + int i, ret;

unsigned int?

>
> ret = ov8856_check_hwcfg(&client->dev);
> if (ret) {
> @@ -1189,10 +1244,50 @@ static int ov8856_probe(struct i2c_client *client)
> return -ENOMEM;
>
> v4l2_i2c_subdev_init(&ov8856->sd, client, &ov8856_subdev_ops);
> + ov8856->xvclk = devm_clk_get(&client->dev, "xvclk");
> + if (PTR_ERR(ov8856->xvclk) == -ENOENT) {
> + dev_info(&client->dev, "xvclk clock not defined, continuing...\n");

How about dev_dbg()?

> + ov8856->xvclk = NULL;
> + } else if (IS_ERR(ov8856->xvclk)) {
> + dev_err(&client->dev, "could not get xvclk clock (%ld)\n",
> + PTR_ERR(ov8856->xvclk));
> + return PTR_ERR(ov8856->xvclk);
> + }
> +
> + ret = clk_set_rate(ov8856->xvclk, OV8856_XVCLK_24);

This should either come from platform data, or perhaps it'd be even better
to get the clock rate and use assigned-clock-rates. I guess that's
preferred nowadays.

> + if (ret < 0) {
> + dev_err(&client->dev, "failed to set xvclk rate (24MHz)\n");
> + return ret;
> + }
> +
> + ov8856->reset_gpio = devm_gpiod_get(&client->dev, "reset",
> + GPIOD_OUT_HIGH);

Indentation.

What if no gpio is defined?

> + if (IS_ERR(ov8856->reset_gpio)) {
> + dev_err(&client->dev, "failed to get reset-gpios\n");
> + return PTR_ERR(ov8856->reset_gpio);
> + }
> +
> + for (i = 0; i < ARRAY_SIZE(ov8856_supply_names); i++)
> + ov8856->supplies[i].supply = ov8856_supply_names[i];
> +
> + ret = devm_regulator_bulk_get(&client->dev,
> + ARRAY_SIZE(ov8856_supply_names),
> + ov8856->supplies);

What happens if there are no regulators?

> + if (ret) {
> + dev_warn(&client->dev, "failed to get regulators\n");
> + return ret;
> + }
> +
> + ret = __ov8856_power_on(ov8856);
> + if (ret) {
> + dev_warn(&client->dev, "failed to power on\n");
> + return ret;
> + }
> +
> ret = ov8856_identify_module(ov8856);
> if (ret) {
> dev_err(&client->dev, "failed to find sensor: %d", ret);
> - return ret;
> + goto probe_power_off;
> }
>
> mutex_init(&ov8856->mutex);
> @@ -1238,6 +1333,9 @@ static int ov8856_probe(struct i2c_client *client)
> v4l2_ctrl_handler_free(ov8856->sd.ctrl_handler);
> mutex_destroy(&ov8856->mutex);
>
> +probe_power_off:
> + __ov8856_power_off(ov8856);
> +

Also remember to power off the device in remove().

> return ret;
> }
>
> @@ -1254,11 +1352,18 @@ static const struct acpi_device_id ov8856_acpi_ids[] = {
> MODULE_DEVICE_TABLE(acpi, ov8856_acpi_ids);
> #endif
>
> +static const struct of_device_id ov8856_of_match[] = {
> + { .compatible = "ovti,ov8856" },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, ov8856_of_match);
> +
> static struct i2c_driver ov8856_i2c_driver = {
> .driver = {
> .name = "ov8856",
> .pm = &ov8856_pm_ops,
> .acpi_match_table = ACPI_PTR(ov8856_acpi_ids),
> + .of_match_table = ov8856_of_match,
> },
> .probe_new = ov8856_probe,
> .remove = ov8856_remove,

--
Regards,

Sakari Ailus