media: i2c: imx258: Use V4L2 legacy sensor clock helper

Several camera sensor drivers access the "clock-frequency" property
directly to retrieve the external clock rate, or modify the clock rate
of the external clock programmatically. Both behaviours are valid on a
subset of ACPI platforms, but are considered deprecated on OF platforms,
and do not support ACPI platforms that implement MIPI DisCo for Imaging.
Implementing them manually in drivers is deprecated, as that can
encourage copying deprecated behaviour for OF platforms in new drivers,
and lead to differences in behaviour between drivers. Instead, drivers
that need to preserve the deprecated OF behaviour should use the
devm_v4l2_sensor_clk_get_legacy() helper.

This driver supports ACPI and OF platforms. The "clocks" property was
not initially specified as mandatory in the DT bindings, and the
"clock-frequency" property has never been  allowed. The driver retrieves
the clock and its rate if present, and falls back to retrieving the rate
from the "clock-frequency" property otherwise. If the rate does not
match the expected rate, the driver fails probing. This is correct
behaviour for ACPI, and deprecated behaviour for OF.

Switch to using the devm_v4l2_sensor_clk_get_legacy() helper. This
preserves setting the clock rate on OF platforms. Should support for OF
platforms that set the clock rate through clock-frequency be considered
unneeded in the future, the driver will only need to switch to
devm_v4l2_sensor_clk_get() without any other change.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mehdi Djait <mehdi.djait@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

diff --git a/drivers/media/i2c/imx258.c b/drivers/media/i2c/imx258.c
index 88d0d7f9d4be1ccc87a662d06fdff0c4ed350003..e50dcfd830f52131e27fa7814788991eba4c1eb1 100644 (file)
--- a/drivers/media/i2c/imx258.c
+++ b/drivers/media/i2c/imx258.c
@@ -1375,18 +1375,13 @@ static int imx258_probe(struct i2c_client *client)
                return dev_err_probe(imx258->dev, ret,
                                     "failed to get regulators\n");
 
-       imx258->clk = devm_clk_get_optional(imx258->dev, NULL);
+       imx258->clk = devm_v4l2_sensor_clk_get_legacy(imx258->dev, NULL, false,
+                                                     0);
        if (IS_ERR(imx258->clk))
                return dev_err_probe(imx258->dev, PTR_ERR(imx258->clk),
                                     "error getting clock\n");
-       if (!imx258->clk) {
-               dev_dbg(imx258->dev,
-                       "no clock provided, using clock-frequency property\n");
 
-               device_property_read_u32(imx258->dev, "clock-frequency", &val);
-       } else {
-               val = clk_get_rate(imx258->clk);
-       }
+       val = clk_get_rate(imx258->clk);
 
        switch (val) {
        case 19200000: