linux-kernel - Re: [PATCH] arm64: dts: hikey: Give wifi some time after power-on

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Date:   Sun, 6 Jan 2019 10:53:05 +0100
From:   Jan Kiszka <jan.kiszka@....de>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        John Stultz <john.stultz@...aro.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Wei Xu <xuwei5@...ilicon.com>, Ryan Grachek <ryan@...ted.us>,
        linux-wireless@...r.kernel.org, "Reizer, Eyal" <eyalr@...com>,
        Valentin Schneider <valentin.schneider@....com>,
        Tony Lindgren <tony@...mide.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        KISHON VIJAY ABRAHAM <kishon@...com>,
        "Mishol, Guy" <guym@...com>,
        Anders Roxell <anders.roxell@...aro.org>,
        Ricardo Salveti <rsalveti@...lveti.net>
Subject: Re: [PATCH] arm64: dts: hikey: Give wifi some time after power-on

On 03.01.19 22:32, Ulf Hansson wrote:
> On Wed, 2 Jan 2019 at 23:21, John Stultz <john.stultz@...aro.org> wrote:
>>
>> Adding a few folks to cc from the thread here:
>> https://patchwork.kernel.org/patch/10734021/
>>
>> As this sounds like a very similar issue.
>> thanks
>> -john
> 
> John, thanks for looping me in.
> 
>>
>> On Sun, Dec 30, 2018 at 3:38 AM Jan Kiszka <jan.kiszka@....de> wrote:
>>>
>>> From: Jan Kiszka <jan.kiszka@...mens.com>
>>>
>>> Somewhere along recent changes to power control of the wl1835, power-on
>>> became very unreliable on the hikey, failing like this:
>>>
>>> wl1271_sdio: probe of mmc2:0001:1 failed with error -16
>>> wl1271_sdio: probe of mmc2:0001:2 failed with error -16
>>>
>>> After playing with some dt parameters and comparing to other users of
>>> this chip, it turned out we need some power-on delay to make things
>>> stable again. In contrast to those other users which define 200 ms, the
>>> hikey is already very happy with 1 ms.
> 
> According to the discussions we had so far, this doesn't sound like
> the correct solution.
> 
> I am intending to post patch soon, however, I am not sure exactly what
> solution to pick yet. I will keep you on cc - and of course I
> appreciate if you could help to test.
> 

FWIW, the Ultra96 is also affected. Here I worked around it by using a 10 ms 
power-on delay. The original workaround from the other thread did not help. 
Looking forward to the proper fix now!

Jan

> Kind regards
> Uffe
> 
>>>
>>> Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
>>> ---
>>>
>>> Tested with 4.19 and linus/master.
>>>
>>>    arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts | 1 +
>>>    1 file changed, 1 insertion(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
>>> b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
>>> index f4964bee6a1a..1e771bf201b9 100644
>>> --- a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
>>> +++ b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
>>> @@ -118,6 +118,7 @@
>>>                  reset-gpios = <&gpio0 5 GPIO_ACTIVE_LOW>;
>>>                  clocks = <&pmic>;
>>>                  clock-names = "ext_clock";
>>> +               post-power-on-delay-ms = <1>;
>>>                  power-off-delay-us = <10>;
>>>          };
>>>
>>> --
>>> 2.16.4