linux-kernel - RE: [PATCH v4 1/2] drivers: watchdog: add a driver to support SAMA5D4 watchdog timer

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Date:	Thu, 6 Aug 2015 08:18:52 +0000
From:	"Yang, Wenyou" <Wenyou.Yang@...el.com>
To:	Guenter Roeck <linux@...ck-us.net>,
	"wim@...ana.be" <wim@...ana.be>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"pawel.moll@....com" <pawel.moll@....com>,
	"mark.rutland@....com" <mark.rutland@....com>,
	"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
	"galak@...eaurora.org" <galak@...eaurora.org>
CC:	"sylvain.rochet@...secur.com" <sylvain.rochet@...secur.com>,
	"Ferre, Nicolas" <Nicolas.FERRE@...el.com>,
	"boris.brezillon@...e-electrons.com" 
	<boris.brezillon@...e-electrons.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH v4 1/2] drivers: watchdog: add a driver to support
 SAMA5D4 watchdog timer

Hi Guenter,

Thank you for your correct.

> -----Original Message-----
> From: Guenter Roeck [mailto:linux@...ck-us.net]
> Sent: 2015年8月6日 16:05
> To: Yang, Wenyou; wim@...ana.be; robh+dt@...nel.org; pawel.moll@....com;
> mark.rutland@....com; ijc+devicetree@...lion.org.uk; galak@...eaurora.org
> Cc: sylvain.rochet@...secur.com; Ferre, Nicolas; boris.brezillon@...e-
> electrons.com; devicetree@...r.kernel.org; linux-kernel@...r.kernel.org; linux-
> watchdog@...r.kernel.org; linux-arm-kernel@...ts.infradead.org
> Subject: Re: [PATCH v4 1/2] drivers: watchdog: add a driver to support SAMA5D4
> watchdog timer
> 
> On 08/05/2015 09:59 PM, Wenyou Yang wrote:
> >>From SAMA5D4, the watchdog timer is upgrated with a new feature,
> > which is describled as in the datasheet, "WDT_MR can be written until
> > a LOCKMR command is issued in WDT_CR".
> > That is to say, as long as the bootstrap and u-boot don't issue a
> > LOCKMR command, WDT_MR can be written more than once in the driver.
> >
> > So the SAMA5D4 watchdog driver's implementation is different from the
> > at91sam9260 watchdog driver implemented in file at91sam9_wdt.c.
> > The user application open the device file to enable the watchdog timer
> > hardware, and close to disable it, and set the watchdog timer timeout
> > by seting WDV and WDD fields of WDT_MR register, and ping the watchdog
> > by issuing WDRSTT command to WDT_CR register with hard-coded key.
> >
> > Signed-off-by: Wenyou Yang <wenyou.yang@...el.com>
> > ---
> [ ... ]
> > +
> > +/* minimum and maximum watchdog timeout, in seconds */
> > +#define	MIN_WDT_TIMEOUT		1
> > +#define	MAX_WDT_TIMEOUT		16
> > +#define	WDT_DEFAULT_TIMEOUT	MAX_WDT_TIMEOUT
> > +
> > +#define	WDT_SEC2TICKS(s)	((s) ? (((s) << 8) - 1) : 0)
> > +
> 
> Why did you replace the spaces after #define with tabs ?
> I understand this is done in the at91.h file, but that is bad enough, it doesn't add
> any value, and I don't see a reason to do it here.
Accepted, Using spaces, not tabs.

> 
> > +
> > +	if ((wdt->config & AT91_WDT_WDFIEN) && irq) {
> > +		ret = devm_request_irq(&pdev->dev, irq,
> sama5d4_wdt_irq_handler,
> > +				       0, pdev->name, pdev);
> 
> I just realized - this interrupt is registered with flags set to 0, while in the at91sam
> driver the flags are "IRQF_SHARED | IRQF_IRQPOLL | IRQF_NO_SUSPEND". Is
> this different with the new SOC ?
No, it is same. It is my carelessness.

> 
> Thanks,
> Guenter


Best Regards,
Wenyou Yang