Re: [PATCH v7 2/3] media: ov8856: Add devicetree support

Robert Foss
2020-05-07T08:39:31Z

On Thu, 7 May 2020 at 10:06, Kao, Ben <ben.kao@intel.com> wrote:
>
> Hi Robert,
>
> On 20-05-05 12:01, Robert Foss wrote:
> > Add match table, enable ov8856_probe() to support both ACPI and DT modes.
> >
> > ACPI and DT modes are primarily distinguished from by checking for ACPI mode
> > and by having resource like be NULL.
> >
> > Signed-off-by: Robert Foss <robert.foss@linaro.org>
> > ---
> >
> > - Changes since v6:
> > * Marco: Bail out of __ov8856_power_on earlier if ACPI mode
> >
> > - Changes since v5:
> > * Maxime & Sakari: Replaced clock tolerance check with warning
> >
> > - Changes since v4:
> > * Maxime & Sakari: Switch to clock-frequency
> >
> > - Changes since v3:
> > * Remove redundant {}-brackets
> > * Compare xvclk_rate to 5% tolerance
> > * Andy: Use dev_fwnode()
> > * Andy: Use %pe instead of %ld + PTR_ERR()
> > * Andy: Invert reset_gpio logic
> > * Andy: Remove dev_dbg() from failing reset_gpio setup
> > * Andy: Use dev_err for logging for failures
> > * Andy: Remove dev_warn from EDEFER/regulator error path
> > * Andy & Sakari: Replaced GPIOD_OUT_XXX with 0/1
> > * Maxime & Sakari: Verify clock frequency from DT
> > * Sakari: Verify the 'xvclk_rate' is set correctly for ACPI/DT devices
> > * Sakari: Remove duplicate ov8856->dev assignment
> >
> > - Changes since v2:
> > * Added "struct device *dev" member to struct ov8856
> > * Andy: Switch to optional version of devm_gpiod_get
> > * Andy: Switch to optional version of devm_clk_get
> > * Fabio: Add reset sleep period
> > * Sakari: Unify defines for 19.2Mhz
> > * Sakari: Remove 24Mhz clock, since it isn't needed for supported modes
> > * Sakari: Replace dev_info() with dev_dbg()
> > * Sakari: Switch induction variable type to unsigned
> > * Sakari: Don't wait for reset_gpio when in ACPI mode
> > * Sakari: Pull reset GPIO high on power on failure
> > * Sakari: Add power on/off to resume/suspend
> > * Sakari: Fix indentation
> > * Sakari: Power off during ov8856_remove()
> > * Sakari: Don't sleep during power-on in ACPI mode
> > * Sakari: Switch to getting xvclk from clk_get_rate
> >
> > - Changes since v1:
> > * Andy & Sakari: Make XVCLK optional since to not break ACPI
> > * 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
> > * Sakari: ARRAY_SIZE() directly instead of through OV8856_NUM_SUPPLIES
> > * Sakari: Use XVCLK rate as provided by DT
> >
> > drivers/media/i2c/ov8856.c | 137 +++++++++++++++++++++++++++++++++----
> > 1 file changed, 123 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/media/i2c/ov8856.c b/drivers/media/i2c/ov8856.c index
> > 8655842af275..e6418a79801e 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>
> > @@ -18,7 +21,7 @@
> > #define OV8856_LINK_FREQ_360MHZ 360000000ULL
> > #define OV8856_LINK_FREQ_180MHZ 180000000ULL
> > #define OV8856_SCLK 144000000ULL
> > -#define OV8856_MCLK 19200000
> > +#define OV8856_XVCLK_19_2 19200000
> > #define OV8856_DATA_LANES 4
> > #define OV8856_RGB_DEPTH 10
> >
> > @@ -64,6 +67,12 @@
> >
> > #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 +575,11 @@ struct ov8856 {
> > struct media_pad pad;
> > struct v4l2_ctrl_handler ctrl_handler;
> >
> > + struct device *dev;
> > + 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 +922,52 @@ 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;
> > +
> > + if (is_acpi_node(dev_fwnode(ov8856->dev)))
> > + return 0;
> > +
> > + ret = clk_prepare_enable(ov8856->xvclk);
> > + if (ret < 0) {
> > + dev_err(&client->dev, "failed to enable xvclk\n");
> > + return ret;
> > + }
> > +
> > + if (ov8856->reset_gpio) {
> > + gpiod_set_value_cansleep(ov8856->reset_gpio, 1);
> > + usleep_range(1000, 2000);
> > + }
> > +
> > + 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, 0);
> > + usleep_range(1500, 1800);
> > +
> > + return 0;
> > +
> > +disable_clk:
> > + gpiod_set_value_cansleep(ov8856->reset_gpio, 1);
> > + clk_disable_unprepare(ov8856->xvclk);
> > +
> > + return ret;
> > +}
> > +
> > +static void __ov8856_power_off(struct ov8856 *ov8856) {
> > + gpiod_set_value_cansleep(ov8856->reset_gpio, 1);
> > + regulator_bulk_disable(ARRAY_SIZE(ov8856_supply_names),
> > + ov8856->supplies);
> > + clk_disable_unprepare(ov8856->xvclk);
> > +}
> > +
> > static int __maybe_unused ov8856_suspend(struct device *dev) {
> > struct i2c_client *client = to_i2c_client(dev); @@ -918,6 +978,7 @@
> > static int __maybe_unused ov8856_suspend(struct device *dev)
> > if (ov8856->streaming)
> > ov8856_stop_streaming(ov8856);
> >
> > + __ov8856_power_off(ov8856);
> > mutex_unlock(&ov8856->mutex);
> >
> > return 0;
> > @@ -931,6 +992,8 @@ static int __maybe_unused ov8856_resume(struct
> > device *dev)
> > int ret;
> >
> > mutex_lock(&ov8856->mutex);
> > +
> > + __ov8856_power_on(ov8856);
> > if (ov8856->streaming) {
> > ret = ov8856_start_streaming(ov8856);
> > if (ret) {
> > @@ -1092,29 +1155,54 @@ static int ov8856_identify_module(struct ov8856
> > *ov8856)
> > return 0;
> > }
> >
> > -static int ov8856_check_hwcfg(struct device *dev)
> > +static int ov8856_get_hwcfg(struct ov8856 *ov8856)
> > {
> > + struct device *dev = ov8856->dev;
> > struct fwnode_handle *ep;
> > struct fwnode_handle *fwnode = dev_fwnode(dev);
> > struct v4l2_fwnode_endpoint bus_cfg = {
> > .bus_type = V4L2_MBUS_CSI2_DPHY
> > };
> > - u32 mclk;
> > + u32 xvclk_rate;
> > int ret;
> > unsigned int i, j;
> >
> > if (!fwnode)
> > return -ENXIO;
> >
> > - ret = fwnode_property_read_u32(fwnode, "clock-frequency", &mclk);
> > + ret = fwnode_property_read_u32(fwnode, "clock-frequency",
> > + &xvclk_rate);
> > if (ret)
> > return ret;
> >
> > - if (mclk != OV8856_MCLK) {
> > - dev_err(dev, "external clock %d is not supported", mclk);
> > - return -EINVAL;
> > + if (!is_acpi_node(fwnode)) {
> > + ov8856->xvclk = devm_clk_get(dev, "xvclk");
> > + if (IS_ERR(ov8856->xvclk)) {
> > + dev_err(dev, "could not get xvclk clock (%pe)\n",
> > + ov8856->xvclk);
> > + return PTR_ERR(ov8856->xvclk);
> > + }
> > +
> > + clk_set_rate(ov8856->xvclk, xvclk_rate);
> > + xvclk_rate = clk_get_rate(ov8856->xvclk);
> > }
> >
> > + if (xvclk_rate != OV8856_XVCLK_19_2)
> > + dev_warn(dev, "external clock rate %d is unsupported",
> > xvclk_rate);
> > +
> > + ov8856->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> > + GPIOD_OUT_LOW);
> > + if (IS_ERR(ov8856->reset_gpio))
> > + 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(dev,
> > ARRAY_SIZE(ov8856_supply_names),
> > + ov8856->supplies);
> > + if (ret)
> > + return ret;
> > +
>
> In case of ACPI this cannot get ov8856->reset_gpio and ov8856->supplies, please add the check for ACPI case:
> if (!is_acpi_node(fwnode)) { }

Do you prefer the explicit check for clarity reasons or for functional reasons?

As far as I understand it, reset_gpio will be NULL and supplies will
be populated with dummy supplies in the ACPI case.
Both can be treated as if they were initialized fully during later
calls to their respective APIs.

>
> Thanks.
> Ben
>
> > ep = fwnode_graph_get_next_endpoint(fwnode, NULL);
> > if (!ep)
> > return -ENXIO;
> > @@ -1169,6 +1257,8 @@ static int ov8856_remove(struct i2c_client *client)
> > pm_runtime_disable(&client->dev);
> > mutex_destroy(&ov8856->mutex);
> >
> > + __ov8856_power_off(ov8856);
> > +
> > return 0;
> > }
> >
> > @@ -1177,22 +1267,31 @@ static int ov8856_probe(struct i2c_client *client)
> > struct ov8856 *ov8856;
> > int ret;
> >
> > - ret = ov8856_check_hwcfg(&client->dev);
> > + ov8856 = devm_kzalloc(&client->dev, sizeof(*ov8856), GFP_KERNEL);
> > + if (!ov8856)
> > + return -ENOMEM;
> > +
> > + ov8856->dev = &client->dev;
> > +
> > + ret = ov8856_get_hwcfg(ov8856);
> > if (ret) {
> > - dev_err(&client->dev, "failed to check HW configuration: %d",
> > + dev_err(&client->dev, "failed to get HW configuration: %d",
> > ret);
> > return ret;
> > }
> >
> > - ov8856 = devm_kzalloc(&client->dev, sizeof(*ov8856), GFP_KERNEL);
> > - if (!ov8856)
> > - return -ENOMEM;
> > -
> > v4l2_i2c_subdev_init(&ov8856->sd, client, &ov8856_subdev_ops);
> > +
> > + ret = __ov8856_power_on(ov8856);
> > + if (ret) {
> > + dev_err(&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 +1337,9 @@ 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);
> > +
> > return ret;
> > }
> >
> > @@ -1254,11 +1356,18 @@ 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,
> > --
> > 2.25.1
>