From: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
To: Vinod Koul <vinod.koul-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: Laxman Dewangan
<ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
djbw-b10kYP2dOMg@public.gmane.org,
linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] dma: tegra: implement suspend/resume callbacks
Date: Thu, 02 May 2013 12:42:30 -0600 [thread overview]
Message-ID: <5182B396.308@wwwdotorg.org> (raw)
In-Reply-To: <20130430103046.GD1960-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
On 04/30/2013 04:30 AM, Vinod Koul wrote:
> On Wed, Apr 24, 2013 at 03:24:27PM +0530, Laxman Dewangan wrote:
>> Implement suspend/resume callbacks to store APB DMA channel's
>> register on suspend and restore APB DMA channel's register on
>> resume.
...
> You dont seem to handle suspend when DMA is active? Otherwise looks fine.
> Stephen, you okay with this patch?
Yes, I think this looks fine. Sorry for the slow response; I was on
vacation.
One question though: Laxman mentioned that DMA clients were responsible
for suspending their DMA accesses themselves. Does the dmaengine core
define the semantics here; are DMA drivers supposed to handle suspend
with active DMAs, or should DMA clients suspend their DMA accesses
themselves as Laxman suggests? If the latter, I wonder if we actually
need to save/restore all the registers, since after resume, a new DMA
access would be started in all cases, which would then reprogram the HW.
WARNING: multiple messages have this Message-ID (diff)
From: Stephen Warren <swarren@wwwdotorg.org>
To: Vinod Koul <vinod.koul@intel.com>
Cc: Laxman Dewangan <ldewangan@nvidia.com>,
djbw@fb.com, linux-tegra@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] dma: tegra: implement suspend/resume callbacks
Date: Thu, 02 May 2013 12:42:30 -0600 [thread overview]
Message-ID: <5182B396.308@wwwdotorg.org> (raw)
In-Reply-To: <20130430103046.GD1960@intel.com>
On 04/30/2013 04:30 AM, Vinod Koul wrote:
> On Wed, Apr 24, 2013 at 03:24:27PM +0530, Laxman Dewangan wrote:
>> Implement suspend/resume callbacks to store APB DMA channel's
>> register on suspend and restore APB DMA channel's register on
>> resume.
...
> You dont seem to handle suspend when DMA is active? Otherwise looks fine.
> Stephen, you okay with this patch?
Yes, I think this looks fine. Sorry for the slow response; I was on
vacation.
One question though: Laxman mentioned that DMA clients were responsible
for suspending their DMA accesses themselves. Does the dmaengine core
define the semantics here; are DMA drivers supposed to handle suspend
with active DMAs, or should DMA clients suspend their DMA accesses
themselves as Laxman suggests? If the latter, I wonder if we actually
need to save/restore all the registers, since after resume, a new DMA
access would be started in all cases, which would then reprogram the HW.
next prev parent reply other threads:[~2013-05-02 18:42 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-24 9:54 [PATCH] dma: tegra: implement suspend/resume callbacks Laxman Dewangan
2013-04-24 9:54 ` Laxman Dewangan
[not found] ` <1366797267-29567-1-git-send-email-ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2013-04-30 10:30 ` Vinod Koul
2013-04-30 10:30 ` Vinod Koul
[not found] ` <20130430103046.GD1960-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2013-04-30 12:42 ` Laxman Dewangan
2013-04-30 12:42 ` Laxman Dewangan
2013-05-02 18:42 ` Stephen Warren [this message]
2013-05-02 18:42 ` Stephen Warren
[not found] ` <5182B396.308-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2013-05-03 3:50 ` Vinod Koul
2013-05-03 3:50 ` Vinod Koul
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