netdev - Re: [PATCH v5 08/24] wfx: add bus

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Date:   Wed, 07 Apr 2021 15:00:17 +0300
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Jérôme Pouiller <jerome.pouiller@...abs.com>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        driverdevel <devel@...verdev.osuosl.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "David S . Miller" <davem@...emloft.net>,
        DTML <devicetree@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        Pali Rohár <pali@...nel.org>
Subject: Re: [PATCH v5 08/24] wfx: add bus_sdio.c

Ulf Hansson <ulf.hansson@...aro.org> writes:

>> If I follow what has been done in other drivers I would write something
>> like:
>>
>>   static int wfx_sdio_suspend(struct device *dev)
>>   {
>>           struct sdio_func *func = dev_to_sdio_func(dev);
>>           struct wfx_sdio_priv *bus = sdio_get_drvdata(func);
>>
>>           config_reg_write_bits(bus->core, CFG_IRQ_ENABLE_DATA, 0);
>>           // Necessary to keep device firmware in RAM
>>           return sdio_set_host_pm_flags(func, MMC_PM_KEEP_POWER);
>
> This will tell the mmc/sdio core to keep the SDIO card powered on
> during system suspend. Thus, it doesn't need to re-initialize it at
> system resume - and the firmware should not need to be re-programmed.
>
> On the other hand, if you don't plan to support system wakeups, it
> would probably be better to power off the card, to avoid wasting
> energy while the system is suspended. I assume that means you need to
> re-program the firmware as well. Normally, it's these kinds of things
> that need to be managed from a ->resume() callback.

Many mac80211 drivers do so that the device is powered off during
interface down (ifconfig wlan0 down), and as mac80211 does interface
down automatically during suspend, suspend then works without extra
handlers.

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