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SubjectRe: [PATCH 02/14] thermal: exynos: Propagate error value from tmu_read()
Date
On Monday, April 16, 2018 02:16:56 PM Daniel Lezcano wrote:
> On 16/04/2018 12:11, Bartlomiej Zolnierkiewicz wrote:
> > From: Marek Szyprowski <m.szyprowski@samsung.com>
> >
> > tmu_read() in case of Exynos4210 might return error for out of bound
> > values. Current code ignores such value, what leads to reporting critical
> > temperature value. Add proper error code propagation to exynos_get_temp()
> > function.
>
> For me the comment in the function exynos4210_tmu_read
>
> /* "temp_code" should range between 75 and 175 */
>
> ... is strange. I would double check this assertion before dealing with
> the error value.

static int exynos4210_tmu_read(struct exynos_tmu_data *data)
{
int ret = readb(data->base + EXYNOS_TMU_REG_CURRENT_TEMP);

/* "temp_code" should range between 75 and 175 */
return (ret < 75 || ret > 175) ? -ENODATA : ret;
}

The value returned by Exynos4210 hardware should be > 75 && < 175 and
it is later used as the "temp_code" parameter for code_to_temp():

static int code_to_temp(struct exynos_tmu_data *data, u16 temp_code)
{
if (data->cal_type == TYPE_ONE_POINT_TRIMMING)
return temp_code - data->temp_error1 + EXYNOS_FIRST_POINT_TRIM;

return (temp_code - data->temp_error1) *
(EXYNOS_SECOND_POINT_TRIM - EXYNOS_FIRST_POINT_TRIM) /
(data->temp_error2 - data->temp_error1) +
EXYNOS_FIRST_POINT_TRIM;
}

so after the current fix the code finally matches the comment.

> > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> > CC: stable@vger.kernel.org # v4.6+
> > Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> > ---
> > drivers/thermal/samsung/exynos_tmu.c | 9 +++++++--
> > 1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
> > index 986cbd0..ac83f72 100644
> > --- a/drivers/thermal/samsung/exynos_tmu.c
> > +++ b/drivers/thermal/samsung/exynos_tmu.c
> > @@ -892,6 +892,7 @@ static void exynos7_tmu_control(struct platform_device *pdev, bool on)
> > static int exynos_get_temp(void *p, int *temp)
> > {
> > struct exynos_tmu_data *data = p;
> > + int value, ret = 0;
> >
> > if (!data || !data->tmu_read || !data->enabled)
> > return -EINVAL;
> > @@ -899,12 +900,16 @@ static int exynos_get_temp(void *p, int *temp)
> > mutex_lock(&data->lock);
> > clk_enable(data->clk);
> >
> > - *temp = code_to_temp(data, data->tmu_read(data)) * MCELSIUS;
> > + value = data->tmu_read(data);
> > + if (value < 0)
> > + ret = value;
> > + else
> > + *temp = code_to_temp(data, value) * MCELSIUS;
> >
> > clk_disable(data->clk);
> > mutex_unlock(&data->lock);
> >
> > - return 0;
> > + return ret;
> > }
> >
> > #ifdef CONFIG_THERMAL_EMULATION

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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