Re: [PATCH] brcmfmac: add support for external 32khz clock

[Arend van Spriel <arend.vanspriel@broadcom.com>]

+ Stefan

On 11/7/2017 2:31 PM, Simon Shields wrote:
> Hi Arend,
>
> On Tue, Nov 07, 2017 at 12:09:23PM +0100, Arend van Spriel wrote:
>> On 11/6/2017 12:27 PM, Simon Shields wrote:
>>> On Mon, Nov 06, 2017 at 11:59:37AM +0100, Arend van Spriel wrote:
>>>> On 11/4/2017 2:24 PM, Simon Shields wrote:
>>>>> Some boards use an external 32khz clock for low-power
>>>>> mode timing. Make sure the clock is powered on while the chipset
>>>>> is active.
>>>>
>>>> Do you have such a board? With the little documentation I can get my hands
>>>> on here I wonder whether the clock needs to be enabled before the device is
>>>> powered. If you have the hardware I would like to check some registers in
>>>> the device.
>>>>
>>>
>>> Yes. Trats2 (exynos4412-based) has such a setup. The BCM4334 works fine
>>> with this patch and one more that enables the WL_REG_EN pin when
>>> brcmfmac is probed.
>>
>> Ok. So this is exactly the thing I was wondering about. So it makes me
>> curious how the WL_REG_EN patch looks like. Can you provide that?
>>
>
> Here[0] is a link to the patch in its current state. Obviously, it's not
> ready at all for mainlining :-)
>
> [0]: https://github.com/fourkbomb/linux/commit/436e59e58b44d856c186fc4767560cecbcbc0c59.patch

Thanks. Indeed doing it in module_init of brcmfmac is not going to fly. 
Actually the MMC stack has a mechanism to power the SDIO device. This 
can be configured through the device tree [1]. I just checked and it 
actually includes specifying the external clock as well.

Regards,
Arend

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt