Vaibhav Hiremath <vaibhav.hiremath@xxxxxxxxxx> writes:
> From: "Jett.Zhou" <jtzhou@xxxxxxxxxxx>
>
> According to some test in emei_dkb, we found some i2c slave device
> (eg. camera sensor ov2659 power up) introduce noise on sda, so detect
> i2c controller busy, and assert reset to i2c controller to recover as
> early as possible to avoid more latency on the entire i2c transaction.
>
> Signed-off-by: Jett.Zhou <jtzhou@xxxxxxxxxxx>
> [vaibhav.hiremath@xxxxxxxxxx: Removed reduction in timeout value, as I
> do not have goot explanation for it. Logically it is not required.
> And also Updated changelog]
> Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@xxxxxxxxxx>
>
> Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@xxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-pxa.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
> index d4c798a..a76c901 100644
> --- a/drivers/i2c/busses/i2c-pxa.c
> +++ b/drivers/i2c/busses/i2c-pxa.c
> @@ -314,6 +314,10 @@ static int i2c_pxa_wait_bus_not_busy(struct pxa_i2c *i2c)
> {
> int timeout = DEF_TIMEOUT;
>
> + if (readl(_ISR(i2c)) & (ISR_IBB | ISR_UB))
> + i2c_pxa_reset(i2c);
The pxa27x manual states in the Developer Manual, chapter 9.4.13 "Reset
Conditions" :
Software must ensure that (1) the I 2 C unit is not busy before it
asserts a reset
Given that, I don't agree with this patch. Moreover, reseting unconditionaly the
i2c bus on each busy state on a write transaction for one single corner case is
not something that has my agreement. A quirk might overcome my reluctance.
Cheers.
--
Robert
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