[alsa-devel] [PATCH 4/5] ASoC: fsl_ssi: use flat regmap cache

[Marek Vasut]

On 09/22/2016 04:37 PM, Maciej S. Szmigiero wrote:
> On 22.09.2016 12:45, Mark Brown wrote:
>> On Thu, Sep 22, 2016 at 01:33:47AM +0200, Maciej S. Szmigiero wrote:
>>
>>> In you patch 5/5 there is backtrace with flat cache, but I meant a
>>> backtrace with original RB tree cache code when warning about allocation
>>> being done in atomic context was generated.
>>
>> I think the conclusion of this and some IRC discussion yesterday is that
>> removing patch 5 fixes things - is that right?
> 
> There are three possible solutions:
> 1) Go back to RB tree cache (revert patch 4) and debug the lockdep warning,
> 2) Keep the flat cache introduced by patch 4 but debug the oops at
> cache init time (while keeping defaults read from hardware),
> 3) Keep both patches and risk the same issues that were previously
> caused by hardcoded register defaults in driver.
> However, Marek says the device works fine for him with the patches.
> 
> It looks to me 1) is an easier and safer solution, especially that
> the driver previously worked fine with RB tree cache.
> I would test this myself but unfortunately I don't have access to
> hardware this week.

I believe switching to flat cache is harmless and it should be a better
mode for devices with small mmio address spaces. After some discussion
on IRC, I believe [1] should resolve the RBTREE crash (?).

[1]
http://git.kernel.org/cgit/linux/kernel/git/broonie/regmap.git/commit/?h=for-next&id=b2c7f5d9c939a37c1ce7f86a642de70e3033ee9e

> Maciej
> 


-- 
Best regards,
Marek Vasut