From: Jisheng Zhang <jszhang@marvell.com>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: <wsa@the-dreams.de>, <linux-i2c@vger.kernel.org>,
<linux-kernel@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] i2c: designware: separate ops for system_sleep_pm and runtime_pm
Date: Tue, 19 May 2015 20:32:42 +0800 [thread overview]
Message-ID: <20150519203242.74617ad6@xhacker> (raw)
In-Reply-To: <20150518082823.GH1490@lahna.fi.intel.com>
Dear Mika,
On Mon, 18 May 2015 11:28:23 +0300
Mika Westerberg <mika.westerberg@linux.intel.com> wrote:
> On Fri, May 15, 2015 at 08:31:39PM +0800, Jisheng Zhang wrote:
> > Commit 1fc2fe204cb9 ("i2c: designware: Add runtime PM hooks") adds
> > runtime pm support using the same ops for system sleep and runtime pm.
> > When suspend to ram, the i2c host may have been runtime suspended, thus
> > i2c_dw_disable() hangs.
>
> It hangs because it has already been powered off, right?
Either be powered off or clock gated or even both.
>
> > This patch fixes this issue by separating ops for system sleep pm and
> > runtime pm, and in the system suspend/resume path, runtime pm apis are
> > used to ensure the device is at correct state.
>
> I can see that this fixes the issue with the platform driver (as the
> platform bus core doesn't power on the device automatically as opposed
> to other buses, like PCI). However, I'm thinking that can we do better
> here.
>
> Instead of powering the device on again, can't we leave it in low power
> state? Recently added 'dev->power.direct_complete' may be used to
> achieve that, I think.
how to handle runtime suspended via just being clock gated? Currently the
only solution is using the runtime pm apis to ensure the device is in a working
state during s2ram. What's your opinion?
Thanks,
Jisheng
next prev parent reply other threads:[~2015-05-19 12:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-15 12:31 [PATCH] i2c: designware: separate ops for system_sleep_pm and runtime_pm Jisheng Zhang
2015-05-18 8:28 ` Mika Westerberg
2015-05-19 12:32 ` Jisheng Zhang [this message]
2015-05-19 13:15 ` Mika Westerberg
2015-05-20 11:34 ` Jisheng Zhang
2015-05-20 12:05 ` Jisheng Zhang
2015-05-20 12:15 ` Mika Westerberg
2015-05-20 12:34 ` Jisheng Zhang
2015-05-20 12:38 ` Jisheng Zhang
2015-05-20 12:55 ` Mika Westerberg
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