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

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Date:   Wed, 16 Jan 2019 21:26:02 +0100
From:   Jan Kiszka <jan.kiszka@....de>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        Tony Lindgren <tony@...mide.com>, Eyal Reizer <eyalr@...com>,
        linux-wireless@...r.kernel.org
Cc:     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@...r.kernel.org, linux-omap@...r.kernel.org
Subject: Re: [PATCH V2] wlcore: sdio: Fixup power on/off sequence

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.

Jan