linux-kernel - Re: [PATCH 10/14] gpio: omap: Drop the concept of gpio banks not being able to lose context.

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Message-ID: <3b01e345-6939-f28c-c648-7316d0a410c4@ti.com>
Date:   Thu, 12 Apr 2018 15:10:34 -0500
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Tony Lindgren <tony@...mide.com>, Keerthy <j-keerthy@...com>
CC:     <linus.walleij@...aro.org>, <t-kristo@...com>, <Russ.Dill@...com>,
        <linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <ssantosh@...nel.org>, <haojian.zhuang@...aro.org>,
        <linux-arm-kernel@...ts.infradead.org>, <d-gerlach@...com>
Subject: Re: [PATCH 10/14] gpio: omap: Drop the concept of gpio banks not
 being able to lose context.



On 04/12/2018 09:22 AM, Tony Lindgren wrote:
> * Keerthy <j-keerthy@...com> [180412 03:56]:
>> From: Russ Dill <Russ.Dill@...com>
>> --- a/drivers/gpio/gpio-omap.c
>> +++ b/drivers/gpio/gpio-omap.c
>> @@ -68,7 +68,7 @@ struct gpio_bank {
>>   	bool dbck_enabled;
>>   	bool is_mpuio;
>>   	bool dbck_flag;
>> -	bool loses_context;
>> +
>>   	bool context_valid;
>>   	int stride;
>>   	u32 width;
> 
> For some SoCs GPIO bank1 won't lose the context ever. So I'd like to
> keep loses_context flag around to avoid pointless save and restore.
> But maybe this still happens with get_context_loss_count and I'm
> misreading this patch?
> 

Agree with Tony here. More over, even if platform supports RTC suspend
(gpio1 context loss) it might support suspend to RAM - gpio1 will not lose context.

Not sure how to handle this correctly now - always-on gpio bank should not be touched 
by omap device framework during suspend otherwise it may hit "in transition" state forever.
>From another side it must be handled the same way as other gpio banks in case of RTC suspend.
Q: How to know if current suspend is RTC suspend and not regular suspend to mem?

> However..
> 
>> @@ -1198,15 +1198,9 @@ static int omap_gpio_probe(struct platform_device *pdev)
>>   #ifdef CONFIG_OF_GPIO
>>   	bank->chip.of_node = of_node_get(node);
>>   #endif
>> -	if (node) {
>> -		if (!of_property_read_bool(node, "ti,gpio-always-on"))
>> -			bank->loses_context = true;
>> -	} else {
>> -		bank->loses_context = pdata->loses_context;
>> -
>> -		if (bank->loses_context)
>> -			bank->get_context_loss_count =
>> -				pdata->get_context_loss_count;
>> +	if (!node) {
>> +		bank->get_context_loss_count =
>> +			pdata->get_context_loss_count;
>>   	}
>>   
>>   	if (bank->regs->set_dataout && bank->regs->clr_dataout)
> 
> .. I do have a patch ready here that I'll post after -rc1 to remove
> CONFIG_OMAP_PM_NOOP related stuff, turns out that's noop anyways :)
> 
> So yeah the pdata->get_context_loss_count parts are noop and can
> be just removed.
> 

-- 
regards,
-grygorii