linux-kernel - Re: [PATCH 3/3] ARM: dts: omap4-sdp: add dynamic pin states for uart3/4

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Message-ID: <51E6C939.40208@ti.com>
Date:	Wed, 17 Jul 2013 19:41:29 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Tony Lindgren <tony@...mide.com>
CC:	Kevin Hilman <khilman@...aro.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<devicetree-discuss@...ts.ozlabs.org>,
	Benoit Cousson <benoit.cousson@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Stephen Warren <swarren@...dotorg.org>
Subject: Re: [PATCH 3/3] ARM: dts: omap4-sdp: add dynamic pin states for uart3/4

Hi,

On 07/17/2013 06:32 PM, Tony Lindgren wrote:
> * Grygorii Strashko <grygorii.strashko@...com> [130717 04:49]:
>> Add dynamic "active"/"idle" pin states for uart3/4 which will be applied
>> when uart3/4 state is switched from active to idle and back by Runtime
>> PM or during system suspend.
>
> This is good for testing code, but should not be merged because
> omap4 has the iopad wake-ups available for uarts. So those can
> be always enabled.

In this case, 2 IRQ will be received per each UART RX event - one from
PRCM and from UART - and that's not good from PM perspective (It will
affect on CPUIdle and CPUFreq at least).

-- log when wake-up enabled always
106:        729          0       GIC 106  OMAP UART2
115:         13          0       GIC 115  mmc0
118:         68          0       GIC 118  mmc1
151:          0          0       GIC 151  twl6040
361:        322          0      PRCM  hwmod_io
             ^^^^
-- log when wake-up enabled only when UART3 (console) is active
106:       1104          0       GIC 106  OMAP UART2
115:         13          0       GIC 115  mmc0
118:         68          0       GIC 118  mmc1
151:          0          0       GIC 151  twl6040
361:          7          0      PRCM  hwmod_io

The same is valid for all devices which will leave WAKEUP_EN set
all the time (

>
>> --- a/arch/arm/boot/dts/omap4-sdp.dts
>> +++ b/arch/arm/boot/dts/omap4-sdp.dts
>> @@ -181,18 +181,40 @@
>>   		pinctrl-single,pins = <
>>   			0x100 (PIN_INPUT_PULLUP | MUX_MODE0)	/* uart3_cts_rctx.uart3_cts_rctx */
>>   			0x102 (PIN_OUTPUT | MUX_MODE0)		/* uart3_rts_sd.uart3_rts_sd */
>> -			0x104 (PIN_INPUT | MUX_MODE0)		/* uart3_rx_irrx.uart3_rx_irrx */
>>   			0x106 (PIN_OUTPUT | MUX_MODE0)		/* uart3_tx_irtx.uart3_tx_irtx */
>>   		>;
>>   	};
>
> This just need to become:
> 		pinctrl-single,pins = <
> 			...
> 			0x104 (WAKEUP_EN | PIN_INPUT_MUX_MODE0)	/* uart3_rx_irrx.uart3_rx_irrx */
> 			...
> 		>;
> 		interrupts = <GIC_SPI 74 IRQ_TYPE_LEVEL_HIGH>;
> 	};
>
> And so on. For am33xx you need to remux things to GPIO for the wake-up
> events, so you should maybe test on that instead.
>
> Regards,
>
> Tony
>

Regards,
- grygorii
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