RE: [PATCH v4] hwmon: (pmbus/max31785) Add delay between bus accesses

[Lakshmi Yadlapati]

On 10/26/23, 6:02 PM, "Guenter Roeck" <groeck7@xxxxxxxxx <mailto:groeck7@xxxxxxxxx> on behalf of linux@xxxxxxxxxxxx <mailto:linux@xxxxxxxxxxxx>> wrote:


On 10/26/23 15:17, Lakshmi Yadlapati wrote:
> The MAX31785 has shown erratic behaviour across multiple system
> designs, unexpectedly clock stretching and NAKing transactions.
> 
> Experimentation shows that this seems to be triggered by a register access
> directly back to back with a previous register write. Experimentation also
> shows that inserting a small delay after register writes makes the issue go
> away.
> 
> Use a similar solution to what the max15301 driver does to solve the same
> problem. Create a custom set of bus read and write functions that make sure
> that the delay is added.
> 
> Signed-off-by: Lakshmi Yadlapati <lakshmiy@xxxxxxxxxx <mailto:lakshmiy@xxxxxxxxxx>>
> ---
> V3 -> V4: Fixed warnings realted to this commit


>I also asked about the use of udelay() instead of usleep_range() or fsleep().
>I see you did not change the code. Fine, but please explain why the use of
>udelay() instead of the alternative is desirable or needed here, and don't
>just ignore review feedback.

Sorry, I missed the comment, I will make changes and send it again.

Thanks,
Lakshmi

>Thanks,
>Guenter