linux-kernel - Re: [PATCH v5 05/13] pm: at91: move the copying the sram function to the sram initializationi phase

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Date:	Fri, 30 Jan 2015 14:20:48 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	"Yang, Wenyou" <Wenyou.Yang@...el.com>,
	"Ferre, Nicolas" <Nicolas.FERRE@...el.com>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>
CC:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"alexandre.belloni@...e-electrons.com" 
	<alexandre.belloni@...e-electrons.com>,
	"sylvain.rochet@...secur.com" <sylvain.rochet@...secur.com>,
	"peda@...ntia.se" <peda@...ntia.se>,
	"linux@...im.org.za" <linux@...im.org.za>
Subject: Re: [PATCH v5 05/13] pm: at91: move the copying the sram function
 to the sram initializationi phase

Hello.

On 1/30/2015 9:54 AM, Yang, Wenyou wrote:

> Thank you for your review and suggestion.

    Not at all.

>> -----Original Message-----
>> From: Sergei Shtylyov [mailto:sergei.shtylyov@...entembedded.com]
>> Sent: Thursday, January 29, 2015 6:11 PM
>> To: Yang, Wenyou; Ferre, Nicolas; linux@....linux.org.uk
>> Cc: linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org;
>> alexandre.belloni@...e-electrons.com; sylvain.rochet@...secur.com;
>> peda@...ntia.se; linux@...im.org.za
>> Subject: Re: [PATCH v5 05/13] pm: at91: move the copying the sram function to
>> the sram initializationi phase

>> Hello.

>> On 1/29/2015 9:38 AM, Wenyou Yang wrote:

>>> To decrease the suspend time, move the copying the sram function to
>>> the sram initialization phase, instead of every time go to suspend.

>>> In the meanwhile, if there is no sram allocated for PM, the PM is not supported.

>>> Signed-off-by: Wenyou Yang <wenyou.yang@...el.com>
>>> Acked-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
>>> ---
>>>    arch/arm/mach-at91/pm.c |   12 +++++++-----
>>>    1 file changed, 7 insertions(+), 5 deletions(-)

>>> diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c index
>>> daa998d..6df0152 100644
>>> --- a/arch/arm/mach-at91/pm.c
>>> +++ b/arch/arm/mach-at91/pm.c
>>> @@ -163,10 +163,6 @@ static int at91_pm_enter(suspend_state_t state)
>>>    			 * turning off the main oscillator; reverse on wakeup.
>>>    			 */
>>>    			if (slow_clock) {
>>> -#ifdef CONFIG_AT91_SLOW_CLOCK
>>> -				/* copy slow_clock handler to SRAM, and call it */
>>> -				memcpy(slow_clock, at91_slow_clock,
>>> at91_slow_clock_sz);
>>> -#endif
>>>    				slow_clock(at91_pmc_base, at91_ramc_base[0],
>>>    					   at91_ramc_base[1],
>>>    					   at91_pm_data.memctrl);
>>> @@ -311,6 +307,9 @@ static void __init at91_pm_sram_init(void)
>>>    	sram_pbase = gen_pool_virt_to_phys(sram_pool, sram_base);
>>>    	slow_clock = __arm_ioremap_exec(sram_pbase, at91_slow_clock_sz,
>>> false);
>>>
>>> +	/* Copy the slow_clock handler to SRAM */
>>> +	memcpy(slow_clock, at91_slow_clock, at91_slow_clock_sz);

>>      AFAIU (looking at the code above and below), __arm_ioremap_exec() can return
>> NULL and in this case memcpy() will cause kernel oops.

> Will add a condition before copying
> 	if (sram_pbase)

    I rather meant *if* (slow_clock).

[...]

> Best Regards,
> Wenyou Yang

WBR, Sergei

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