linux-kernel - Re: [PATCH] ARM: rockchip: restore dapswjdp after suspend

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Date:	Thu, 21 May 2015 08:40:55 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	"Huang, Tao" <huangtao@...k-chips.com>
Cc:	Heiko Stuebner <heiko@...ech.de>,
	Russell King <linux@....linux.org.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
	Chris Zhong <zyw@...k-chips.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Tony Xie <tony.xie@...k-chips.com>
Subject: Re: [PATCH] ARM: rockchip: restore dapswjdp after suspend

Huang Tao,

On Wed, May 20, 2015 at 7:02 PM, Huang, Tao <huangtao@...k-chips.com> wrote:
>> It turns out that's not a safe assumption.  In some cases (pending
>> interrupts) it's possible that the WFI might act as a no-op and the
>> MaskROM will never run.
>
>
> I don't think this can happen. It seems we set PMU_GLOBAL_INT_DISABLE
> bit, which means in power off flow, the IRQ will not accepted until the
> ARM is power off. Do you see the SGRF_CPU_CON0[0] is 0 after resume?

>From testing, it appears that it can happen that the WFI might act as a no-op.

...but you're right in pointing out that unless we can solve the
PMU_GLOBAL_INT_DISABLE() problem then this patch here to fix
DAPDEVICEEN isn't too useful.  I was hoping to fix the
PMU_GLOBAL_INT_DISABLE() in
<https://chromium-review.googlesource.com/#/c/272442/> or find a
similar solution.  ...if we can's solve that though, then I'm not sure
what to suggest.


> Anyway, restore the value is okay, which make the code more symmetrically

OK.  Heiko: applying this won't hurt, but it will only be useful if we
find a way to return from the WFI successfully...

-Doug
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