From: t.figa@samsung•com (Tomasz Figa)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2] ARM: save/restore diagnostic register on Cortex-A9 suspend/resume
Date: Tue, 24 Jun 2014 19:40:27 +0200 [thread overview]
Message-ID: <53A9B80B.7020608@samsung.com> (raw)
In-Reply-To: <20140624163320.GM9121@arm.com>
Hi Will,
On 24.06.2014 18:33, Will Deacon wrote:
> On Tue, Jun 24, 2014 at 05:28:54PM +0100, Tomasz Figa wrote:
>> Hi Shawn,
>>
>> On 22.06.2014 12:15, Shawn Guo wrote:
>>> The CP15 diagnostic register holds ARM errata bits on Cortex-A9, so it
>>> needs to be saved/restored on suspend/resume. Otherwise, the
>>> effectiveness of errata workaround gets lost together with diagnostic
>>> register bit across suspend/resume cycle.
>>>
>>> The patch adds a couple of Cortex-A9 specific suspend and resume
>>> functions to handle the diagnostic register across suspend/resume cycle.
>>
>> [snip]
>>
>>> +ENTRY(cpu_ca9mp_do_resume)
>>> + ldmia r0!, {r4}
>>> + mcr p15, 0, r4, c15, c0, 1 @ Diagnostic register
>>
>> What about platforms running in non-secure mode in which the register is
>> read-only?
>
> On A9, it should be write-ignore. Are you seeing problems on a real SoC?
I'm observing a complete system hang on Exynos4412-based Trats2 board if
I try to write this register in resume from system-wide sleep.
Note that the board is running under secure firmware, but there is no
support for suspend/resume of such boards in mainline yet, so I'm
testing on a work in progress (but mostly finished) series that is yet
to be sent.
Best regards,
Tomasz
next prev parent reply other threads:[~2014-06-24 17:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-22 10:15 [PATCH v2] ARM: save/restore diagnostic register on Cortex-A9 suspend/resume Shawn Guo
2014-06-24 16:28 ` Tomasz Figa
2014-06-24 16:33 ` Will Deacon
2014-06-24 17:40 ` Tomasz Figa [this message]
2014-06-24 18:17 ` Will Deacon
2014-07-01 14:44 ` Russell King - ARM Linux
2014-07-01 16:26 ` Tomasz Figa
2014-07-02 12:34 ` Will Deacon
2014-07-02 14:01 ` Lorenzo Pieralisi
2014-07-02 14:26 ` Russell King - ARM Linux
2014-07-04 3:31 ` Shawn Guo
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