Re: [PATCH] mfd: intel_soc_pmic_chtdc_ti: Set use_single_read regmap_config flag

[Hans de Goede <hansg@kernel.org>]

Hi Andy,

On 4-Aug-25 10:47 AM, Andy Shevchenko wrote:
> On Mon, Aug 4, 2025 at 10:34 AM Hans de Goede <hansg@kernel.org> wrote:
>>
>> Testing has shown that reading multiple registers at once (for 10 bit
>> adc values) does not work. Set the use_single_read regmap_config flag
>> to make regmap split these for is.
>>
>> This should fix temperature opregion accesses done by
>> drivers/acpi/pmic/intel_pmic_chtdc_ti.c and is also necessary for
>> the upcoming drivers for the ADC and battery MFD cells.
> 
> ...
> 
>> +       /* Reading multiple registers at once is not supported */
>> +       .use_single_read = true,
> 
> By HW or by problem in regmap as being suggested here:
> https://lore.kernel.org/linux-gpio/CALNFmy1ZRqHz6_DD_2qamm-iLQ51AOFQH=ahCWRN7SAk3pfZ_A@mail.gmail.com/
> ?

This is a hw limitation. I tried with i2ctransfer to directly
access the chip and it returns invalid values (1) after
the first byte read.

> As a quick fix I am fine with this.
> Reviewed-by: Andy Shevchenko <andy@kernel.org>

Thank you.

Regards,

Hans


1) I don't remember if it was 0, 0xff or repeating
of the first byte. But it definitely did not work.