linux-kernel - Re: [PATCH 2/2] regmap: mmio: Parse endianness definitions from DT

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Date:	Thu, 31 Mar 2016 15:23:44 +0900
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Mark Brown <broonie@...nel.org>
Cc:	Alexander Stein <alexander.stein@...tec-electronic.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] regmap: mmio: Parse endianness definitions from DT

On Thu, Mar 31, 2016 at 3:09 PM, Krzysztof Kozlowski
<k.kozlowski@...sung.com> wrote:
> On Wed, Mar 30, 2016 at 4:41 AM, Mark Brown <broonie@...nel.org> wrote:
>> Since we changed to do formatting in the bus we now skip all the format
>> parsing that the core does for its data marshalling code.  This means
>> that we skip the DT parsing it does which breaks some systems, we need
>> to add an explict call in the MMIO code to do this.
>>
>> Reported-by: Alexander Stein <alexander.stein@...tec-electronic.com>
>> Signed-off-by: Mark Brown <broonie@...nel.org>
>
> This breaks my syscon reboot handler (Exynos4412, Trats2):
> ###############
> -sh-4.1# reboot
> Rebooting.
> [   37.056210] reboot: Restarting system
> [   38.058649] Unable to restart system
> [   39.060987] Reboot failed -- System halted
> ###############
>
> I added a printk before switch and:
> config->val_format_endian: REGMAP_ENDIAN_DEFAULT
> regmap_get_val_endian(): REGMAP_ENDIAN_BIG,
>

... and the big-endian is coming from the last return in
regmap_get_val_endian() (/* Use this if no other value was found */).
I don't have endian property in DTS for the syscon device so it always
ended with default which in the regmap_mmio_gen_context() was mapped
to little endian. Now default is big endian.

I guess the big/little endian property should be required in that case.

Best regards,
Krzysztof