On Wed, 29 Apr 2020 at 11:00, Maxime Ripard <maxime@xxxxxxxxxx> wrote:
>
> Hi,
>
> On Tue, Apr 28, 2020 at 08:07:17PM +0200, Robert Foss wrote:
> > Add match table, enable ov8856_probe() to support
> > both ACPI and DT modes.
> >
> > ACPI and DT modes are primarily distinguished from
> > each other by relying on devm_XXX_get_optional()
> > will return NULL instead of a reference for the
> > desired managed resource.
> >
> > Signed-off-by: Robert Foss <robert.foss@xxxxxxxxxx>
> > ---
> >
> > - 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 | 139 +++++++++++++++++++++++++++++++++----
> > 1 file changed, 126 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/media/i2c/ov8856.c b/drivers/media/i2c/ov8856.c
> > index 8655842af275..48b02b8d205f 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;
> > +
> > + ret = clk_prepare_enable(ov8856->xvclk);
> > + if (ret < 0) {
> > + dev_err(&client->dev, "failed to enable xvclk\n");
> > + return ret;
> > + }
> > +
> > + if (is_acpi_node(dev_fwnode(ov8856->dev)))
> > + return 0;
> > +
> > + 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 +1155,58 @@ 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);
> > + 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);
> > + }
> > +
> > + /* external clock must be 19.2MHz, allow 5% tolerance */
>
> Where is that 5% tolerance coming from? Experimentations, datasheets, something
> that looks good enough? Either way, this should be in the comment.
I don't have access to the full datasheet unfortunately. A 24Mhz rate
is as far as I understand it supported and required for higher
bandwidth count modes.
It was suggested to me that adding a tolerance is the best practice,
the ov5645 driver uses a 1% tolerance, which may be more appropriate.
The closest frequency to 19.2Mhz * 1.05 I'm able to generate is 24Mhz,
which works. But unfortunately my testing platform sdm845-db845c is
not able to generate lower frequencies than 19.2Mhz.
This all adds up to a pretty unclear picture of what is supported, if
anyone has access to the full documentation I would like to make the
tolerances and comments reflect that.
>
> Maxime
