Date:   Wed, 23 Jan 2019 21:17:34 +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 23.01.19 09:50, Ulf Hansson wrote:
> On Tue, 22 Jan 2019 at 17:08, Jan Kiszka <jan.kiszka@....de> wrote:
>>
>> On 21.01.19 15:40, Ulf Hansson wrote:
>>> On Fri, 18 Jan 2019 at 16:09, Ulf Hansson <ulf.hansson@...aro.org> wrote:
>>>>
>>>> On Fri, 18 Jan 2019 at 13:09, Jan Kiszka <jan.kiszka@....de> wrote:
>>>>>
>>>>> 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.
>>>>
>>>> Alright, sounds great. However, I need to defer that to Monday/Tuesday
>>>> next week.
>>>>
>>>>>
>>>>>>
>>>>>> 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.
>>>>
>>>> I see. Good to know, thanks!
>>>>
>>>>>
>>>>> Jan
>>>>>
>>>>> [1]
>>>>> https://github.com/siemens/jailhouse-images/blob/next/recipes-kernel/linux/files/arm64_defconfig_4.19
>>>>
>>>> I have looked through the log and the defconfig. No obvious things
>>>> found at this point. Thanks for sharing them!
>>>>
>>>
>>> So, I have put together a debug patch, mostly to verify that things
>>> seems to be correct in regards to runtime PM. It should produce some
>>> prints to the log, particular during power on/off of the SDIO card and
>>> during probe of the wifi driver. Please re-run the test on top of the
>>> v2 version of the $subject patch.
>>>
>>
>> Log attached.
>
> Thanks! Okay, so the re-initialization of the SDIO card is failing,
> that's very valuable information.
>
> I noticed one difference while comparing your log with the one I
> received (offlist) from Anders... In your case the initialization
> frequency that works the first time is 300KHz, while in Anders case
> it's 100KHz. This sounds a bit fishy to me, so maybe there are some
> problems with the pwrseq after all.
>
> Let me think a bit and see what I can come up with as a possible solution.
>
> In the meantime, can you re-run the test with same debug patch, but
> change the post-power-on-delay-ms to let's say 10 ms in the DTS? I am
> going to ask Anders to do the same test on his side, as to see if we
> get different values of the found initialization frequency.

Here is a log with 10 ms power-on-delay.

Jan

View attachment "wlan-ok.log" of type "text/x-log" (33079 bytes)

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