linux-kernel - Re: [PATCH V2] wlcore: sdio: Fixup power on/off sequence

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Date:   Fri, 18 Jan 2019 13:09:42 +0100
From:   Jan Kiszka <jan.kiszka@....de>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Kalle Valo <kvalo@...eaurora.org>,
        Tony Lindgren <tony@...mide.com>, Eyal Reizer <eyalr@...com>,
        linux-wireless@...r.kernel.org,
        Ricardo Salveti <rsalveti@...lveti.net>,
        Kishon Vijay Abraham I <kishon@...com>,
        Anders Roxell <anders.roxell@...aro.org>,
        John Stultz <john.stultz@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-omap <linux-omap@...r.kernel.org>
Subject: Re: [PATCH V2] wlcore: sdio: Fixup power on/off sequence

On 17.01.19 10:54, Ulf Hansson wrote:
> On Wed, 16 Jan 2019 at 21:26, Jan Kiszka <jan.kiszka@....de> wrote:
>>
>> On 16.01.19 12:37, Ulf Hansson wrote:
>>> During "wlan-up", we are programming the FW into the WiFi-chip. However,
>>> re-programming the FW doesn't work, unless a power cycle of the WiFi-chip
>>> is made in-between the programmings.
>>>
>>> To conform to this requirement and to fix the regression in a simple way,
>>> let's start by allowing that the SDIO card (WiFi-chip) may stay powered on
>>> (runtime resumed) when wl12xx_sdio_power_off() returns. The intent with the
>>> current code is to treat this scenario as an error, but unfortunate this
>>> doesn't work as expected, so let's fix this.
>>>
>>> The other part is to guarantee that a power cycle of the SDIO card has been
>>> completed when wl12xx_sdio_power_on() returns, as to allow the FW
>>> programming to succeed. However, relying solely on runtime PM to deal with
>>> this isn't sufficient. For example, userspace may prevent runtime suspend
>>> via sysfs for the device that represents the SDIO card, leading to that the
>>> mmc core also keeps it powered on. For this reason, let's instead do a
>>> brute force power cycle in wl12xx_sdio_power_on().
>>>
>>> Fixes: 728a9dc61f13 ("wlcore: sdio: Fix flakey SDIO runtime PM handling")
>>> Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
>>> ---
>>>
>>> Changes in v2:
>>>        - Keep the SDIO host claimed when calling mmc_hw_reset().
>>>        - Add a fixes tag.
>>> ---
>>>    drivers/net/wireless/ti/wlcore/sdio.c | 15 +++++++--------
>>>    1 file changed, 7 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/net/wireless/ti/wlcore/sdio.c b/drivers/net/wireless/ti/wlcore/sdio.c
>>> index bd10165d7eec..4d4b07701149 100644
>>> --- a/drivers/net/wireless/ti/wlcore/sdio.c
>>> +++ b/drivers/net/wireless/ti/wlcore/sdio.c
>>> @@ -164,6 +164,12 @@ static int wl12xx_sdio_power_on(struct wl12xx_sdio_glue *glue)
>>>        }
>>>
>>>        sdio_claim_host(func);
>>> +     /*
>>> +      * To guarantee that the SDIO card is power cycled, as required to make
>>> +      * the FW programming to succeed, let's do a brute force HW reset.
>>> +      */
>>> +     mmc_hw_reset(card->host);
>>> +
>>>        sdio_enable_func(func);
>>>        sdio_release_host(func);
>>>
>>> @@ -174,20 +180,13 @@ static int wl12xx_sdio_power_off(struct wl12xx_sdio_glue *glue)
>>>    {
>>>        struct sdio_func *func = dev_to_sdio_func(glue->dev);
>>>        struct mmc_card *card = func->card;
>>> -     int error;
>>>
>>>        sdio_claim_host(func);
>>>        sdio_disable_func(func);
>>>        sdio_release_host(func);
>>>
>>>        /* Let runtime PM know the card is powered off */
>>> -     error = pm_runtime_put(&card->dev);
>>> -     if (error < 0 && error != -EBUSY) {
>>> -             dev_err(&card->dev, "%s failed: %i\n", __func__, error);
>>> -
>>> -             return error;
>>> -     }
>>> -
>>> +     pm_runtime_put(&card->dev);
>>>        return 0;
>>>    }
>>>
>>>
>>
>> Just tested on both HiKey (620) and Ultra96 but it fails to fix the issue on
>> both. I'm getting
>>
>> wl1271_sdio: probe of mmc2:0001:1 failed with error -16
>>
>> during boot again, and the interface is not available.
>
> Okay, sounds like this may be a different problem then. Can you share
> the complete log and the kernel config?

You can find the config here [1], log from the HiKey boot attached.

> I can prepare a debug patch as well, if you are willing to re-run the test?

Sure, send it over, I can run it.

>
> Adding a post-power-on-delay-ms of 1 ms as you suggested [1], doesn't
> sounds like the correct solution to me, unless I am overlooking some
> things. The point is, since the mmc core succeeds to detect and
> initialize the SDIO card, the power sequence seems to be correct.

Yeah, I'm not claiming at all I know what I'm doing there, just that it happens
to work.

Jan

[1]
https://github.com/siemens/jailhouse-images/blob/next/recipes-kernel/linux/files/arm64_defconfig_4.19

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