* Re: [PATCH v2] iio: adc: mt6360: Handle error in cleanup path correctly
2025-09-29 16:24 ` [PATCH v2] iio: adc: mt6360: Handle error in cleanup path correctly Haotian Zhang
@ 2025-10-04 14:31 ` Jonathan Cameron
0 siblings, 0 replies; 2+ messages in thread
From: Jonathan Cameron @ 2025-10-04 14:31 UTC (permalink / raw)
To: Haotian Zhang
Cc: linux-iio, Lars-Peter Clausen, Matthias Brugger,
AngeloGioacchino Del Regno, Abhash Jha, Al Viro, linux-kernel,
linux-arm-kernel, linux-mediatek
On Tue, 30 Sep 2025 00:24:53 +0800
Haotian Zhang <vulab@iscas.ac.cn> wrote:
> The return value of a regmap_raw_write() and regmap_update_bits()
> in the cleanup path was being ignored.
>
> Fix this by checking the return value and warn on error.
>
> Fixes: 1f4877218f7e ("iio: adc: mt6360: Add ADC driver for MT6360")
> Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
>
> ---
> Changes in v2:
> - Do not propagate cleanup path errors.
> - Log a warning on failure instead of overwriting the return value, as
> suggested by the maintainer.
As below. I think dev_err() is appropriate.
> - Also check the return value of regmap_update_bits() for consistency.
> ---
> drivers/iio/adc/mt6360-adc.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/adc/mt6360-adc.c b/drivers/iio/adc/mt6360-adc.c
> index 69b3569c90e5..9ee7247aacbe 100644
> --- a/drivers/iio/adc/mt6360-adc.c
> +++ b/drivers/iio/adc/mt6360-adc.c
> @@ -70,6 +70,7 @@ static int mt6360_adc_read_channel(struct mt6360_adc_data *mad, int channel, int
> ktime_t predict_end_t, timeout;
> unsigned int pre_wait_time;
> int ret;
> + int cleanup_ret;
>
> mutex_lock(&mad->adc_lock);
>
> @@ -130,11 +131,16 @@ static int mt6360_adc_read_channel(struct mt6360_adc_data *mad, int channel, int
> out_adc_conv:
> /* Only keep ADC enable */
> adc_enable = cpu_to_be16(MT6360_ADCEN_MASK);
> - regmap_raw_write(mad->regmap, MT6360_REG_PMUADCCFG, &adc_enable, sizeof(adc_enable));
> + cleanup_ret = regmap_raw_write(mad->regmap, MT6360_REG_PMUADCCFG,
> + &adc_enable, sizeof(adc_enable));
> + if (cleanup_ret)
> + dev_warn(mad->dev, "Failed to reset ADC config: %d\n", cleanup_ret);
Why warn? If this happens it's definite and error and may bite us later.
> mad->last_off_timestamps[channel] = ktime_get();
> /* Config prefer channel to NO_PREFER */
> - regmap_update_bits(mad->regmap, MT6360_REG_PMUADCRPT1, MT6360_PREFERCH_MASK,
> + cleanup_ret = regmap_update_bits(mad->regmap, MT6360_REG_PMUADCRPT1, MT6360_PREFERCH_MASK,
> MT6360_NO_PREFER << MT6360_PREFERCH_SHFT);
> + if (cleanup_ret)
> + dev_warn(mad->dev, "Failed to reset prefer channel: %d\n", cleanup_ret);
> out_adc_lock:
> mutex_unlock(&mad->adc_lock);
>
Maybe it is worth trying to surface the error if nothing else has already gone wrong. That is a little fiddly
to do but something like
if (cleanup_ret) {
dev_err()
ret = ret ?: cleanup_ret;
}
I'm not sure it is worth the complexity however, so perhaps see if others have comments on this
in next few days before spinning a v3.
Thanks,
Jonathan
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