linux-kernel - Re: [PATCH v2 1/2] ARM: rockchip: add support holding 24Mhz osc during suspend

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Date:	Mon, 22 Jun 2015 13:04:02 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Chris Zhong <zyw@...k-chips.com>
Cc:	Heiko Stübner <heiko@...ech.de>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
	Sonny Rao <sonnyrao@...omium.org>,
	Alexandru Stan <amstan@...gle.com>,
	Dmitry Torokhov <dtor@...gle.com>,
	Russell King <linux@....linux.org.uk>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] ARM: rockchip: add support holding 24Mhz osc
 during suspend

Chris,

On Sun, Jun 21, 2015 at 3:00 AM, Chris Zhong <zyw@...k-chips.com> wrote:
> If we want to wake up system via usb, the 24Mhz osc could not be
> disabled during suspend, read the usb phy SIDDQ bit to decide whether
> to switch to 32khz clock-in.
>
> Signed-off-by: Chris Zhong <zyw@...k-chips.com>
> ---
>
>  arch/arm/mach-rockchip/pm.c | 38 ++++++++++++++++++++++++++++++++++++--
>  1 file changed, 36 insertions(+), 2 deletions(-)

As talked about privately, this patch is ugly.  ...but I don't see a
solution that is less ugly.  This method has the advantages that it is
"automatic"--the system figures out whether it needs the 24MHz clock
automatically based on whether the PHYs were left on.  No other
communication / device tree stuff is needed.


> +       /* if any usb phy is still on(GRF_SIDDQ==0), that means we need the
> +        * function of usb wakeup, so do not switch to 32khz, since the usb phy
> +        * clk does not connect to 32khz osc*/

This is not _quite_ the block commenting style used in this file.  It
would be a bit nicer if it matched.

Other than that:

Reviewed-by: Douglas Anderson <dianders@...omium.org>

On the chromeos-3.14 kernel (with the WIP dwc2 patches):
Tested-by: Douglas Anderson <dianders@...omium.org>
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