We found a bug that i2c transfer sometimes failed on 3066a board with
stabel-4.8, the con register would be updated by uninitialized tuning
value, it made the i2c transfer failed.
So give the tuning value to be zero during rk3x_i2c_v0_calc_timings.
Signed-off-by: David Wu <[email protected]>
---
drivers/i2c/busses/i2c-rk3x.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
index 50702c7..df22066 100644
--- a/drivers/i2c/busses/i2c-rk3x.c
+++ b/drivers/i2c/busses/i2c-rk3x.c
@@ -694,6 +694,8 @@ static int rk3x_i2c_v0_calc_timings(unsigned long clk_rate,
t_calc->div_low--;
t_calc->div_high--;
+ /* Give the tuning value 0, that would not update con register */
+ t_calc->tuning = 0;
/* Maximum divider supported by hw is 0xffff */
if (t_calc->div_low > 0xffff) {
t_calc->div_low = 0xffff;
--
1.9.1
Hi:
On 2016年10月22日 16:43, David Wu wrote:
> We found a bug that i2c transfer sometimes failed on 3066a board with
> stabel-4.8, the con register would be updated by uninitialized tuning
> value, it made the i2c transfer failed.
>
> So give the tuning value to be zero during rk3x_i2c_v0_calc_timings.
>
> Signed-off-by: David Wu <[email protected]>
> ---
> drivers/i2c/busses/i2c-rk3x.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
> index 50702c7..df22066 100644
> --- a/drivers/i2c/busses/i2c-rk3x.c
> +++ b/drivers/i2c/busses/i2c-rk3x.c
> @@ -694,6 +694,8 @@ static int rk3x_i2c_v0_calc_timings(unsigned long clk_rate,
> t_calc->div_low--;
> t_calc->div_high--;
>
> + /* Give the tuning value 0, that would not update con register */
> + t_calc->tuning = 0;
> /* Maximum divider supported by hw is 0xffff */
> if (t_calc->div_low > 0xffff) {
> t_calc->div_low = 0xffff;
rk3066a based board can't boot up(with endless i2c irq messages print
out) from linux-4.8 without this fix.
Tested-by: Andy Yan <[email protected]>
Hi,
On Sat, Oct 22, 2016 at 1:43 AM, David Wu <[email protected]> wrote:
> We found a bug that i2c transfer sometimes failed on 3066a board with
> stabel-4.8, the con register would be updated by uninitialized tuning
> value, it made the i2c transfer failed.
>
> So give the tuning value to be zero during rk3x_i2c_v0_calc_timings.
>
> Signed-off-by: David Wu <[email protected]>
> ---
> drivers/i2c/busses/i2c-rk3x.c | 2 ++
> 1 file changed, 2 insertions(+)
Reviewed-by: Douglas Anderson <[email protected]>
On Sat, Oct 22, 2016 at 04:43:42PM +0800, David Wu wrote:
> We found a bug that i2c transfer sometimes failed on 3066a board with
> stabel-4.8, the con register would be updated by uninitialized tuning
> value, it made the i2c transfer failed.
>
> So give the tuning value to be zero during rk3x_i2c_v0_calc_timings.
>
> Signed-off-by: David Wu <[email protected]>
Added stable and applied to for-current, thanks!
On Sat, Oct 22, 2016 at 04:43:42PM +0800, David Wu wrote:
> We found a bug that i2c transfer sometimes failed on 3066a board with
> stabel-4.8, the con register would be updated by uninitialized tuning
> value, it made the i2c transfer failed.
>
> So give the tuning value to be zero during rk3x_i2c_v0_calc_timings.
>
> Signed-off-by: David Wu <[email protected]>
What I missed to say in my review:
Please use a subject line that describes WHY the change is needed not so
much WHAT is done. Like: "fix missing initialization causing boot
problems"