Hi Bryan,
On 7/14/24 12:33 AM, Bryan O'Donoghue wrote:
The ov5675 specification says that the gap between XSHUTDN deassert and the first I2C transaction should be a minimum of 8192 XVCLK cycles.
Right now we use a usleep_rage() that gives a sleep time of between about 430 and 860 microseconds.
On the Lenovo X13s we have observed that in about 1/20 cases the current timing is too tight and we start transacting before the ov5675's reset cycle completes, leading to I2C bus transaction failures.
The reset racing is sometimes triggered at initial chip probe but, more usually on a subsequent power-off/power-on cycle e.g.
[ 71.451662] ov5675 24-0010: failed to write reg 0x0103. error = -5 [ 71.451686] ov5675 24-0010: failed to set plls
The current quiescence period we have is too tight. Instead of expressing the post reset delay in terms of the current XVCLK this patch converts the power-on and power-off delays to the maximum theoretical delay @ 6 MHz with an additional buffer.
1.365 milliseconds on the power-on path is 1.5 milliseconds with grace. 85.3 microseconds on the power-off path is 90 microseconds with grace.
Fixes: 49d9ad719e89 ("media: ov5675: add device-tree support and support runtime PM") Cc: stable@vger.kernel.org Signed-off-by: Bryan O'Donoghue bryan.odonoghue@linaro.org
Reviewed-by: Quentin Schulz quentin.schulz@cherry.de
Doesn't seem to break my camera on RK3399 Puma on Haikou with Haikou Video Demo adapter, so:
Tested-by: Quentin Schulz quentin.schulz@cherry.de # RK3399 Puma with Haikou Video Demo
Thanks! Quentin