[alsa-devel] [PATCH] ASoC: fsl_ssi: remove explicit register defaults

[Maciej S. Szmigiero]

On 01.02.2016 13:25, Maciej S. Szmigiero wrote:
> On 01.02.2016 13:13, Fabio Estevam wrote:
>> Hi Maciej,
>>
>> On Mon, Feb 1, 2016 at 10:07 AM, Maciej S. Szmigiero
>> <mail at maciej.szmigiero.name> wrote:
>>> Is regmap patch from
>>> http://www.spinics.net/lists/kernel/msg2161934.html
>>> applied to the tested tree?
>>
>> Yes, linux-next 20160201 contains this patch.
> 
> Hmm, I will try to build this tree on UDOO board
> today and see what happens.

Looks like the problem occurs because commit
922a9f936e40 ("regmap: mmio: Convert to regmap_bus and fix accessor usage")
has removed ->read callback from MMIO regmap
implementation but it is used (via regmap_raw_read()) by
regcache code to initialize cache if reg default values
weren't provided explicitly.

If I revert this commit the SSI probes successfully again.

Looks like a possible solution would be to change
regmap_raw_read() to do read using _regmap_read in
case the cache is bypassed and there is no ->read
callback defined for regmap implementation.

Maciej