From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Ujfalusi <peter.ujfalusi@ti.com>
Subject: Re: [PATCH 1/2] mfd: twl6040: Fix deferred probe handling for clk32k
Date: Mon, 21 Sep 2015 12:55:46 +0300
Message-ID: <55FFD422.2080506@ti.com>
References: <1442593745-16725-1-git-send-email-tony@atomide.com>
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To: Tony Lindgren <tony@atomide.com>, linux-omap@vger.kernel.org
Cc: Samuel Ortiz <sameo@linux.intel.com>, "Dr. H. Nikolaus Schaller" <hns@goldelico.com>, Grazvydas Ignotas <notasas@gmail.com>, Benoit Cousson <bcousson@baylibre.com>, Lee Jones <lee.jones@linaro.org>, linux-arm-kernel@lists.infradead.org
List-Id: linux-omap@vger.kernel.org

On 09/18/2015 07:29 PM, Tony Lindgren wrote:
> Commit 68bab8662f49 ("mfd: twl6040: Optional clk32k clock handling")
> added clock handling for the 32k clock from palmas-clk. However, that
> patch did not consider a typical situation where twl6040 is built-in,
> and palmas-clk is a loadable module like we have in omap2plus_defconfig.
> =

> If palmas-clk is not loaded before twl6040 probes, we will get a
> "clk32k is not handled" warning during booting. This means that any
> drivers relying on this clock will mysteriously fail, including
> omap5-uevm WLAN and audio.
> =

> Note that for WLAN, we probably should also eventually get
> the clk32kgaudio for MMC3 directly as that's shared between
> audio and WLAN SDIO at least for omap5-uevm. It seems the
> WLAN chip cannot get it as otherwise MMC3 won't get properly
> probed.

While this is going to 'fix' the WLAN because currently the twl6040 is powe=
red
on all the time (32k clock is enabled). My plan is to finally implement the
power state handling for the twl6040, which means that w/o audio activity t=
he
twl6040 will be turned off. This will imply that any clock which is only us=
ed
by twl6040 will be off as well.
The proper solution would be to add clock handling to the WLAN driver stack.

Otherwise:
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

> Fixes: 68bab8662f49 ("mfd: twl6040: Optional clk32k clock handling")
> Cc: Benoit Cousson <bcousson@baylibre.com>
> Cc: Dr. H. Nikolaus Schaller <hns@goldelico.com>
> Cc: Grazvydas Ignotas <notasas@gmail.com>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
> Cc: Samuel Ortiz <sameo@linux.intel.com>
> Cc: Sourav Poddar <sourav.poddar@ti.com>
> Signed-off-by: Tony Lindgren <tony@atomide.com>
> ---
>  drivers/mfd/twl6040.c | 2 ++
>  1 file changed, 2 insertions(+)
> =

> --- a/drivers/mfd/twl6040.c
> +++ b/drivers/mfd/twl6040.c
> @@ -647,6 +647,8 @@ static int twl6040_probe(struct i2c_client *client,
>  =

>  	twl6040->clk32k =3D devm_clk_get(&client->dev, "clk32k");
>  	if (IS_ERR(twl6040->clk32k)) {
> +		if (PTR_ERR(twl6040->clk32k) =3D=3D -EPROBE_DEFER)
> +			return -EPROBE_DEFER;
>  		dev_info(&client->dev, "clk32k is not handled\n");
>  		twl6040->clk32k =3D NULL;
>  	}
> =



-- =

P=E9ter