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References: <20181217164207.20081-1-tony@atomide.com>
In-Reply-To: <20181217164207.20081-1-tony@atomide.com>
From:   Ricardo Salveti <rsalveti@rsalveti.net>
Date:   Mon, 17 Dec 2018 23:06:53 -0200
Message-ID: <CAHYQr0oXExQeyo1z52hsNeQY78TMH3rt7egMJQ+uDHKS1_pBfw@mail.gmail.com>
Subject: Re: [PATCH] wlcore: Fix bringing up wlan0 again if powered down briefly
To:     Tony Lindgren <tony@atomide.com>
Cc:     Kalle Valo <kvalo@codeaurora.org>, Eyal Reizer <eyalr@ti.com>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Guy Mishol <guym@ti.com>, linux-wireless@vger.kernel.org,
        linux-omap@vger.kernel.org,
        Anders Roxell <anders.roxell@linaro.org>,
        John Stultz <john.stultz@linaro.org>,
        Ulf Hansson <ulf.hansson@linaro.org>
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Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

Hi,

On Mon, Dec 17, 2018 at 2:42 PM Tony Lindgren <tony@atomide.com> wrote:
>
> At least HiKey board can fail to bring up wireless interface again
> if the interface is brought down and up with no delay inbetween.
>
> This can be done tested with:
>
> # while true; do ifconfig wlan0 down; ifconfig wlan0 up; done
>
> According to Ricardo Salveti <rsalveti@rsalveti.net>, we need to
> wait between 30 - 40 ms on HiKey. This seems to happen when we
> get -EBUSY returned by pm_runtime_put() basedon the check in
> rpm_check_suspend_allowed(). But as it still unclear if part of
> the delay needed is because of capacitance, let's always do a
> at least 50 ms msleep even if no -EBUSY is returned.
>
> Cc: Anders Roxell <anders.roxell@linaro.org>
> Cc: Eyal Reizer <eyalr@ti.com>
> Cc: John Stultz <john.stultz@linaro.org>
> Cc: Ricardo Salveti <rsalveti@rsalveti.net>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Reported-by: Ricardo Salveti <rsalveti@rsalveti.net>
> Fixes: 60f36637bbbd ("wlcore: sdio: allow pm to handle sdio power")
> Signed-off-by: Tony Lindgren <tony@atomide.com>
> ---
>
> Uffe, do you have some better ideas on how to fix this issue?
>
> ---
>  drivers/net/wireless/ti/wlcore/sdio.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/ti/wlcore/sdio.c b/drivers/net/wireless/ti/wlcore/sdio.c
> --- a/drivers/net/wireless/ti/wlcore/sdio.c
> +++ b/drivers/net/wireless/ti/wlcore/sdio.c
> @@ -174,7 +174,7 @@ 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;
> +       int error, retries = 5;
>
>         sdio_claim_host(func);
>         sdio_disable_func(func);
> @@ -188,6 +188,17 @@ static int wl12xx_sdio_power_off(struct wl12xx_sdio_glue *glue)
>                 return error;
>         }
>
> +       /* Wait a bit to ensure the card gets power off. Otherwise
> +        * bringing interface down and up again may not power off the
> +        * card inbetween. And then firmware load will fail on trying
> +        * to bring the card up again. We need to wait between 30 - 40
> +        * ms for this based on measurements on HiKey board.
> +        */
> +       do {
> +               msleep(50);
> +       } while (error == -EBUSY && !pm_runtime_suspended(&card->dev) &&
> +                retries--);
> +
>         return 0;
>  }
>
> --
> 2.19.2

Tested with 'while true; do ifconfig wlan0 down; ifconfig wlan0 up;
done' for 3 hours on HiKey, HiKey960 and BeagleBone Black Wireless, no
issues.

Tested-by: Ricardo Salveti <rsalveti@rsalveti.net>

Thanks,
-- 
Ricardo Salveti de Araujo