linux-kernel - Re: [PATCH 1/2] power: reset: at91: add sama5d3 reset function

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Date:	Fri, 10 Jul 2015 09:59:53 +0800
From:	Josh Wu <josh.wu@...el.com>
To:	Guenter Roeck <linux@...ck-us.net>
CC:	Nicolas Ferre <nicolas.ferre@...el.com>,
	<linux-arm-kernel@...ts.infradead.org>,
	Wei Yongjun <yongjun_wei@...ndmicro.com.cn>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Ben Dooks <ben.dooks@...ethink.co.uk>,
	<linux-kernel@...r.kernel.org>,
	"Krzysztof Kozlowski" <k.kozlowski.k@...il.com>,
	Sebastian Reichel <sre@...nel.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Fabian Frederick <fabf@...net.be>, <linux-pm@...r.kernel.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>
Subject: Re: [PATCH 1/2] power: reset: at91: add sama5d3 reset function

Hi, Guenter

On 7/10/2015 1:37 AM, Guenter Roeck wrote:
> On Thu, Jul 09, 2015 at 06:15:46PM +0800, Josh Wu wrote:
>> As since sama5d3, to reset the chip, we don't need to shutdown the ddr
>> controller.
>>
>> So add a new compatible string and new restart function for sama5d3 and
>> later chips. As we don't use sama5d3 ddr controller, so remove it as
>> well.
>>
> That sounds like it should be two separate patches, or am I missing something ?

I think using one patch makes more sense. Maybe the commit log is not 
clear enough. How about put it this way:

This patch introduces a new compatible string: "atmel,sama5d3-rstc" for 
the reset driver of sama5d3 and later chips.
As in sama5d3 or later chips, we don't have to shutdown the DDR 
controller before reset. Shutdown the DDR controller before reset is a 
workaround to avoid DDR signal driving the bus, but since sama5d3 and 
later chips there is no such a conflict.
That means:
   1. the sama5d3 reset function only need to write the rstc register 
and return.
   2. for sama5d3, we can remove the code related with DDR controller as 
we don't use it at all.

Best Regards,
Josh Wu
>
> Guenter
>
>> Signed-off-by: Josh Wu <josh.wu@...el.com>
>> Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
>> ---
>>
>>   drivers/power/reset/at91-reset.c | 30 +++++++++++++++++++++---------
>>   1 file changed, 21 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
>> index 36dc52f..8944b63 100644
>> --- a/drivers/power/reset/at91-reset.c
>> +++ b/drivers/power/reset/at91-reset.c
>> @@ -123,6 +123,14 @@ static int at91sam9g45_restart(struct notifier_block *this, unsigned long mode,
>>   	return NOTIFY_DONE;
>>   }
>>   
>> +static int sama5d3_restart(struct notifier_block *this, unsigned long mode,
>> +			void *cmd)
>> +{
>> +	writel(cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST),
>> +				at91_rstc_base);
>> +	return NOTIFY_DONE;
>> +}
>> +
>>   static void __init at91_reset_status(struct platform_device *pdev)
>>   {
>>   	u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
>> @@ -155,13 +163,13 @@ static void __init at91_reset_status(struct platform_device *pdev)
>>   static const struct of_device_id at91_ramc_of_match[] = {
>>   	{ .compatible = "atmel,at91sam9260-sdramc", },
>>   	{ .compatible = "atmel,at91sam9g45-ddramc", },
>> -	{ .compatible = "atmel,sama5d3-ddramc", },
>>   	{ /* sentinel */ }
>>   };
>>   
>>   static const struct of_device_id at91_reset_of_match[] = {
>>   	{ .compatible = "atmel,at91sam9260-rstc", .data = at91sam9260_restart },
>>   	{ .compatible = "atmel,at91sam9g45-rstc", .data = at91sam9g45_restart },
>> +	{ .compatible = "atmel,sama5d3-rstc", .data = sama5d3_restart },
>>   	{ /* sentinel */ }
>>   };
>>   
>> @@ -181,17 +189,21 @@ static int at91_reset_of_probe(struct platform_device *pdev)
>>   		return -ENODEV;
>>   	}
>>   
>> -	for_each_matching_node(np, at91_ramc_of_match) {
>> -		at91_ramc_base[idx] = of_iomap(np, 0);
>> -		if (!at91_ramc_base[idx]) {
>> -			dev_err(&pdev->dev, "Could not map ram controller address\n");
>> -			return -ENODEV;
>> +	match = of_match_node(at91_reset_of_match, pdev->dev.of_node);
>> +	at91_restart_nb.notifier_call = match->data;
>> +
>> +	if (match->data != sama5d3_restart) {
>> +		/* we need to shutdown the ddr controller, so get ramc base */
>> +		for_each_matching_node(np, at91_ramc_of_match) {
>> +			at91_ramc_base[idx] = of_iomap(np, 0);
>> +			if (!at91_ramc_base[idx]) {
>> +				dev_err(&pdev->dev, "Could not map ram controller address\n");
>> +				return -ENODEV;
>> +			}
>> +			idx++;
>>   		}
>> -		idx++;
>>   	}
>>   
>> -	match = of_match_node(at91_reset_of_match, pdev->dev.of_node);
>> -	at91_restart_nb.notifier_call = match->data;
>>   	return register_restart_handler(&at91_restart_nb);
>>   }
>>   
>> -- 
>> 1.9.1
>>

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