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

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Message-ID: <20190116154311.GP5544@atomide.com>
Date:   Wed, 16 Jan 2019 07:43:11 -0800
From:   Tony Lindgren <tony@...mide.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Kalle Valo <kvalo@...eaurora.org>, 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>,
        Jan Kiszka <jan.kiszka@....de>, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org
Subject: Re: [PATCH V2] wlcore: sdio: Fixup power on/off sequence

* Ulf Hansson <ulf.hansson@...aro.org> [190116 11:37]:
> 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.

This v2 version works for me as tested with:

# while [ 1 ]; do ifconfig wlan0 down; ifconfig wlan0 up; done
[  181.364990] wlcore: down
[  182.116424] wlcore: firmware booted (Rev 6.3.10.0.141)
[  182.151641] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
[  182.166778] wlcore: down
[  182.773132] wlcore: firmware booted (Rev 6.3.10.0.141)
[  182.811096] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
...

Thanks for fixing this issue properly, and feel free to add:

Tested-by: Tony Lindgren <tony@...mide.com>