This is a note to let you know that I've just added the patch titled
media: ov5640: Handle delays when no reset_gpio set
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
media-ov5640-handle-delays-when-no-reset_gpio-set.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 5c8cac4885355d3768c3838a5da5b63d6b8ebfb3
Author: Jai Luthra <j-luthra@xxxxxx>
Date: Tue Jan 3 13:27:36 2023 +0100
media: ov5640: Handle delays when no reset_gpio set
[ Upstream commit d7ff69139908842adf824be4f50c7e9ac5886c04 ]
Some module manufacturers [1][2] don't expose the RESETB and PWDN pins
of the sensor directly through the 15-pin FFC connector. Instead wiring
~PWDN gpio to the sensor pins with appropriate delays.
In such cases, reset_gpio will not be available to the driver, but it
will still be toggled when the sensor is powered on, and thus we should
still honor the wait time of >= 5ms + 1ms + 20ms (see figure 2-3 in [3])
before attempting any i/o operations over SCCB.
Also, rename the function to ov5640_powerup_sequence to better match the
datasheet (section 2.7).
[1] https://digilent.com/reference/_media/reference/add-ons/pcam-5c/pcam_5c_sch.pdf
[2] https://www.alinx.com/public/upload/file/AN5641_User_Manual.pdf
[3] https://cdn.sparkfun.com/datasheets/Sensors/LightImaging/OV5640_datasheet.pdf
Fixes: 19a81c1426c1 ("[media] add Omnivision OV5640 sensor driver")
Reported-by: Nishanth Menon <nm@xxxxxx>
Signed-off-by: Jai Luthra <j-luthra@xxxxxx>
Reviewed-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>
Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
index f31b096e018f2..873087e180561 100644
--- a/drivers/media/i2c/ov5640.c
+++ b/drivers/media/i2c/ov5640.c
@@ -2425,11 +2425,22 @@ static void ov5640_power(struct ov5640_dev *sensor, bool enable)
gpiod_set_value_cansleep(sensor->pwdn_gpio, enable ? 0 : 1);
}
-static void ov5640_reset(struct ov5640_dev *sensor)
+/*
+ * From section 2.7 power up sequence:
+ * t0 + t1 + t2 >= 5ms Delay from DOVDD stable to PWDN pull down
+ * t3 >= 1ms Delay from PWDN pull down to RESETB pull up
+ * t4 >= 20ms Delay from RESETB pull up to SCCB (i2c) stable
+ *
+ * Some modules don't expose RESETB/PWDN pins directly, instead providing a
+ * "PWUP" GPIO which is wired through appropriate delays and inverters to the
+ * pins.
+ *
+ * In such cases, this gpio should be mapped to pwdn_gpio in the driver, and we
+ * should still toggle the pwdn_gpio below with the appropriate delays, while
+ * the calls to reset_gpio will be ignored.
+ */
+static void ov5640_powerup_sequence(struct ov5640_dev *sensor)
{
- if (!sensor->reset_gpio)
- return;
-
if (sensor->pwdn_gpio) {
gpiod_set_value_cansleep(sensor->reset_gpio, 0);
@@ -2478,8 +2489,7 @@ static int ov5640_set_power_on(struct ov5640_dev *sensor)
goto xclk_off;
}
- ov5640_reset(sensor);
- ov5640_power(sensor, true);
+ ov5640_powerup_sequence(sensor);
ret = ov5640_init_slave_id(sensor);
if (ret)
