Date:   Mon, 21 Jan 2019 15:40:38 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Jan Kiszka <jan.kiszka@....de>
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 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.

Kind regards
Uffe

View attachment "0001-wlcore-sdio-mmc-Debug-for-runtime-PM-and-power-on-of.patch" of type "text/x-patch" (8009 bytes)

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