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SubjectRe: Using regmap_update_bits to update a write only register
On Fri, Mar 6, 2015 at 2:45 PM, Lars-Peter Clausen <> wrote:
> On 03/06/2015 12:21 PM, Mark Brown wrote:
>> On Thu, Mar 05, 2015 at 08:14:14PM +0200, Daniel Baluta wrote:
>>> On Mar 5, 2015 7:54 PM, "Mark Brown" <> wrote:
>>>> Probably, or there's a bug. What should happen is that if the register
>>>> default appeared successfully then the read will get statisfied from the
>>>> cache in the manner you describe - presumably that's gone wrong somehow.
>>>> Have you set num_reg_defaults? That's the obvious thing...
>>> Did that. I will have a closer look. Thanks for the answer.
>> OK, the other thing that springs to mind to check is that the register
>> didn't somehow get marked as volatile.

Checked that! is_volatile_reg returns false for that register.

> There were some bugs in the past were non-readable register automatically
> got marked as volatile, this has been fixed though a few months ago. Try to
> make sure you use the latest upstream version of regmap.

Thanks for pointing this out. I am using 3.19. Changing from
REGCACHE_RBTREE to REGCACHE_FLAT fixed the problem for me.

I will update my sources and try again with REGCACHE_RBTREE when
I'll have some time.


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