linux-kernel - RE: [PATCH 2/2] rtc: omap: add rtc wakeup support to alarm events

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Date:	Fri, 14 Jun 2013 11:38:41 +0000
From:	"Hebbar, Gururaja" <gururaja.hebbar@...com>
To:	Kevin Hilman <khilman@...aro.org>
CC:	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"zonque@...il.com" <zonque@...il.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	"rob@...dley.net" <rob@...dley.net>,
	"a.zummo@...ertech.it" <a.zummo@...ertech.it>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"rtc-linux@...glegroups.com" <rtc-linux@...glegroups.com>,
	"davinci-linux-open-source@...ux.davincidsp.com" 
	<davinci-linux-open-source@...ux.davincidsp.com>,
	"Bedia, Vaibhav" <vaibhav.bedia@...com>,
	"Rajashekhara, Sudhakar" <sudhakar.raj@...com>
Subject: RE: [PATCH 2/2] rtc: omap: add rtc wakeup support to alarm events

On Fri, Jun 14, 2013 at 03:51:43, Kevin Hilman wrote:
> "Hebbar, Gururaja" <gururaja.hebbar@...com> writes:
> 
> > Hi Kevin,
> >
> > On Mon, Jun 10, 2013 at 16:55:17, Hebbar, Gururaja wrote:
> >> On Fri, May 31, 2013 at 23:11:22, Kevin Hilman wrote:
> >> > Hebbar Gururaja <gururaja.hebbar@...com> writes:
> >> > 
> >> > > On some platforms (like AM33xx), a special register (RTC_IRQWAKEEN)
> >> > > is available to enable Wakeup feature for Alarm Events.
> >> > >
> >> > > Since new platforms/Boards are now added through DT only, this feature
> >> > > is supported via DT property only.
> >> > 
> >> > > Platforms using such IP should add the property "ti,has_irq_wake_enb"
> >> > > in rtc DT node.
> >> > 
> >> > This is a property of the IP, not the board.  Can't you detect this
> >> > based on the revision of the IP?
> >> 
> >> Here is what I found out till now.
> >> 
> >> 1. rtc-omap driver is used by Davinci, OMAP-1/2 & AM33xx SoC.
> >> 
> >> 2. Only AM33xx soc rtc ip has revision register (& populated). Older OMAP
> >>    Or davinci doesn't have this register.
> >> 
> >> 3. AFAIK, this was the reason why Afzal used platform_device_id & 
> >>    of_device_id->data method to detect new versions (commit
> >>    9e0344dcc225fe1a0e8b8af9ff7df44ec4613580)
> >> 
> >> 
> >> So now either 
> >> a. I can follow the same method and add new member to omap_rtc_devtype & add a new compatible in 
> >>  omap_rtc_of_match in rtc-omap.c
> >> 
> >> or
> >> 
> >> b. use dt property to indicate existence of above property.
> >> 
> >> 
> >> Kindly let me know your opinion about the same.
> >
> > Any update on this. I have patch ready for both the choices. Waiting for your ok to send
> 
> I think (a) is better.

Ok. I will add the property using a new DT compatibility.


> 
> The driver should always do a device_init_wakeup(dev, true), *except*
> for devtypes that don't have this feature.

"wakeup capable" and "irq-wake-enable-for-alarm-event" are different

For "irq-wake-enable-for-alarm-event", I will add a new DT compability.

However, wakeup capable notification is done in another patch using the a 
DT property "ti,wakeup_capable".

The reason for using a dt property is specified below


	commit fa5b07820fe3a0fc06ac368516e71f10a59b9539
	Author: Sekhar Nori <nsekhar@...com>
	Date:   Wed Oct 27 15:33:05 2010 -0700

	rtc: omap: let device wakeup capability be configured from chip
	init logic

	The rtc-omap driver currently hardcodes the RTC wakeup
	capability to be "not capable".  While this seems to be true for
	existing OMAP1 boards which are not wired for this, the
	DA850/OMAP-L138 SoC, the RTC can always be wake up source from
	its "deep sleep" mode.


So I cannot directly add device_init_wakeup(dev, true), inside driver code.
So, I added a DT property




> 
> Kevin
> 
> 


Regards, 
Gururaja
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