Re: [PATCH] thermal: rockchip: fix handling of invalid readings

Caesar Wang
2015-08-10T06:31:50Z

Dear Dmitry,

Thanks your patch.

The code looks like fine,but I don't think the TS-ADC will work on
rk3288 SoC.

在 2015年08月08日 04:59, Dmitry Torokhov 写道:
> We attempted to signal invalid code by returning -EAGAIN from
> rk_tsadcv2_code_to_temp(), unfortunately the return value was stuffed
> directly into the temperature pointer, potentially confusing upper
> layers with temperature of -EINVAL.
>
> Let's split temperature from error/success indicator to avoid such
> confusion.
>
> Also change the way we scan the temperature table to start with the 2nd
> element so that we do not need to worry that we may reference out of
> bounds element while doing binary search and keep checking that we end
> up with 'mid' equal to 0 (since we are looking for the temperature that
> would fall into interval between the 'mid' and 'mid - 1') .
>
> Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
> ---
> drivers/thermal/rockchip_thermal.c | 28 +++++++++++++---------------
> 1 file changed, 13 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/thermal/rockchip_thermal.c b/drivers/thermal/rockchip_thermal.c
> index c89ffb2..93ee307 100644
> --- a/drivers/thermal/rockchip_thermal.c
> +++ b/drivers/thermal/rockchip_thermal.c
> @@ -124,7 +124,7 @@ struct rockchip_thermal_data {
> #define TSADCV2_AUTO_PERIOD_HT_TIME 50 /* msec */
>
> struct tsadc_table {
> - unsigned long code;
> + u32 code;
> long temp;
> };
>
> @@ -164,7 +164,6 @@ static const struct tsadc_table v2_code_table[] = {
> {3452, 115000},
> {3437, 120000},
> {3421, 125000},
> - {0, 125000},
> };
>
> static u32 rk_tsadcv2_temp_to_code(long temp)
> @@ -191,19 +190,21 @@ static u32 rk_tsadcv2_temp_to_code(long temp)
> return 0;
> }
>
> -static int rk_tsadcv2_code_to_temp(u32 code)
> +static int rk_tsadcv2_code_to_temp(u32 code, int *temp)
> {
> - unsigned int low = 0;
> + unsigned int low = 1;
> unsigned int high = ARRAY_SIZE(v2_code_table) - 1;
> unsigned int mid = (low + high) / 2;
> unsigned int num;
> unsigned long denom;
>
> - /* Invalid code, return -EAGAIN */
> - if (code > TSADCV2_DATA_MASK)
> - return -EAGAIN;
> + BUILD_BUG_ON(ARRAY_SIZE(v2_code_table) < 2);
>
> - while (low <= high && mid) {
> + code &= TSADCV2_DATA_MASK;
> + if (code < v2_code_table[high].code)
> + return -EAGAIN; /* Incorrect reading */
> +
> + while (low <= high) {
> if (code >= v2_code_table[mid].code &&
> code < v2_code_table[mid - 1].code)
> break;
> @@ -223,7 +224,9 @@ static int rk_tsadcv2_code_to_temp(u32 code)
> num = v2_code_table[mid].temp - v2_code_table[mid - 1].temp;
> num *= v2_code_table[mid - 1].code - code;
> denom = v2_code_table[mid - 1].code - v2_code_table[mid].code;
> - return v2_code_table[mid - 1].temp + (num / denom);
> + *temp = v2_code_table[mid - 1].temp + (num / denom);
> +
> + return 0;
> }
>
> /**
> @@ -281,14 +284,9 @@ static int rk_tsadcv2_get_temp(int chn, void __iomem *regs, int *temp)
> {
> u32 val;
>
> - /* the A/D value of the channel last conversion need some time */
> val = readl_relaxed(regs + TSADCV2_DATA(chn));
> - if (val == 0)
> - return -EAGAIN;
> -

if we reserve the above code, that will get the ADC value.

> - *temp = rk_tsadcv2_code_to_temp(val);
>
> - return 0;
> + return rk_tsadcv2_code_to_temp(val, temp);
> }
>
> static void rk_tsadcv2_tshut_temp(int chn, void __iomem *regs, long temp)