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SubjectRE: [PATCH] usb: musb: fix context save over suspend.
Date
Hi,

I faced the same issue on OMAP4 and made similar fix a week ago: http://review.omapzoom.org/31700 but in this patch I also check is the MUSB is already suspended (so the context is already saved) in .suspend callback so reading/writing to MUSB register is more safe.
It is almost same solution as we had a long time ago.

--
Best regards,
Ruslan Bilovol

________________________________________
From: linux-usb-owner@vger.kernel.org [linux-usb-owner@vger.kernel.org] on behalf of Igor Grinberg [grinberg@compulab.co.il]
Sent: Tuesday, January 22, 2013 11:12 AM
To: NeilBrown
Cc: Balbi, Felipe; Greg Kroah-Hartman; linux-usb@vger.kernel.org; linux-kernel@vger.kernel.org; linux-omap@vger.kernel.org; Kevin Hilman
Subject: Re: [PATCH] usb: musb: fix context save over suspend.

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It looks like Kevin has a new address:
Kevin Hilman <khilman@deeprootsystems.com>

On 01/21/13 23:38, NeilBrown wrote:
> On Mon, 21 Jan 2013 13:38:59 +0200 Igor Grinberg <grinberg@compulab.co.il>
> wrote:
>
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>
>> Hi Neil,
>
>> On 01/21/13 11:28, NeilBrown wrote:
>>>
>>>
>>> The standard suspend sequence involves runtime_resuming
>>> devices before suspending the system.
>>> So just saving context in runtime_suspend and restoring it
>>> in runtime resume isn't enough. We must also save in "suspend"
>>> and restore in "resume".
>>>
>>> Without this patch, and OMAP3 system with off_mode enabled will find
>>> the musb port non-functional after suspend/resume. With the patch it
>>> works perfectly.
>
>> Hmmm... Some time ago, this has been removed in
>> 5d193ce8 (usb: musb: PM: fix context save/restore in suspend/resume path)
>
>> Am I missing something? Or things changed and now this patch is correct?
>
> Hi Igor,
> thanks for alerting me to that patch .... does anyone else get the feeling
> that power management to too complex to be understood by a mere human?
>
> That commit (5d193ce8) suggests that the musb-hdrc device is an
> 'omap_device', or maybe has a PM domain set to something else.
> However it isn't/doesn't. dev->pm_domain is NULL. So no PM domain layer
> will ever call the musb_core musb_runtime_suspend/resume.
>
> The parent device - musb-omap2430 - is an omap device, does have pm_domain
> set, and does have its omap2430_runtime_suspend/resume called for system
> suspend and so the context for that device is saved and restored.
> However that doesn't help the context for musb-hdrc.
>
> Whether musb ever was an omap_device is beyond my archaeological skills to
> determine.
>
> Kevin: Was musb-hdrc ever a device with a pm_domain? or was it only ever
> the various possible parents that had domains?
> Are you able to defend your earlier patch in today's kernel? It
> certainly causes my device not to work properly.
>
> Thanks,
> NeilBrown
>
>
>
>
>>>
>>> Signed-off-by: NeilBrown <neilb@suse.de>
>>>
>>> diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
>>> index fd34867..b6ccc02 100644
>>> --- a/drivers/usb/musb/musb_core.c
>>> +++ b/drivers/usb/musb/musb_core.c
>>> @@ -2225,6 +2225,7 @@ static int musb_suspend(struct device *dev)
>>> }
>>>
>>> spin_unlock_irqrestore(&musb->lock, flags);
>>> + musb_save_context(musb);
>>> return 0;
>>> }
>>>
>>> @@ -2234,6 +2235,8 @@ static int musb_resume_noirq(struct device *dev)
>>> * unless for some reason the whole soc powered down or the USB
>>> * module got reset through the PSC (vs just being disabled).
>>> */
>>> + struct musb *musb = dev_to_musb(dev);
>>> + musb_restore_context(musb);
>>> return 0;
>>> }
>>>
>
>> - --
>> Regards,
>> Igor.
>>


- --
Regards,
Igor.
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