linux-kernel - Re: [PATCH 13/18] ARM: at91/rtc-at91sam9: pass the GPBR to use via ressources

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Date:	Mon, 20 Feb 2012 10:16:47 +0100
From:	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Ryan Mallon <rmallon@...il.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 13/18] ARM: at91/rtc-at91sam9: pass the GPBR to use via
 ressources

On 07:36 Mon 20 Feb     , Russell King - ARM Linux wrote:
> On Mon, Feb 20, 2012 at 02:20:10AM +0100, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > On 11:43 Mon 20 Feb     , Ryan Mallon wrote:
> > > On 18/02/12 04:50, Nicolas Ferre wrote:
> > > 
> > > > From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
> > > > 
> > > > The GPBR registers are used for storing RTC values. The GPBR registers
> > > > to use are now provided using standard resource entry. The array is
> > > > filled in SoC specific code.
> > > > rtc-at91sam9 RTT as RTC driver is modified to retrieve this information.
> > > > 
> > > > Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
> > > > Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
> > > > ---
> > > >  arch/arm/mach-at91/at91sam9260_devices.c      |   10 +++++++-
> > > >  arch/arm/mach-at91/at91sam9261_devices.c      |    8 ++++++-
> > > >  arch/arm/mach-at91/at91sam9263_devices.c      |   16 +++++++++++--
> > > >  arch/arm/mach-at91/at91sam9g45_devices.c      |    8 ++++++-
> > > >  arch/arm/mach-at91/at91sam9rl_devices.c       |    8 ++++++-
> > > >  arch/arm/mach-at91/include/mach/at91sam9260.h |    5 +--
> > > >  arch/arm/mach-at91/include/mach/at91sam9261.h |    5 +--
> > > >  arch/arm/mach-at91/include/mach/at91sam9263.h |    5 +--
> > > >  arch/arm/mach-at91/include/mach/at91sam9g45.h |    5 +--
> > > >  arch/arm/mach-at91/include/mach/at91sam9rl.h  |    2 +-
> > > >  drivers/rtc/rtc-at91sam9.c                    |   29 +++++++++++++++++++++---
> > > >  11 files changed, 76 insertions(+), 25 deletions(-)
> > > > 
> > > > diff --git a/arch/arm/mach-at91/at91sam9260_devices.c b/arch/arm/mach-at91/at91sam9260_devices.c
> > > > index 2071017..ae2b648 100644
> > > > --- a/arch/arm/mach-at91/at91sam9260_devices.c
> > > > +++ b/arch/arm/mach-at91/at91sam9260_devices.c
> > > > @@ -718,14 +718,16 @@ static struct resource rtt_resources[] = {
> > > >  		.start	= AT91SAM9260_BASE_RTT,
> > > >  		.end	= AT91SAM9260_BASE_RTT + SZ_16 - 1,
> > > >  		.flags	= IORESOURCE_MEM,
> > > > -	}
> > > > +	}, {
> > > > +		.flags	= IORESOURCE_MEM,
> > > > +	},
> > > >  };
> > > >  
> > > >  static struct platform_device at91sam9260_rtt_device = {
> > > >  	.name		= "at91_rtt",
> > > >  	.id		= 0,
> > > >  	.resource	= rtt_resources,
> > > > -	.num_resources	= ARRAY_SIZE(rtt_resources),
> > > > +	.num_resources	= 1,
> > > 
> > > 
> > > Why this change? The device has two resources, and the rtc driver
> > > request both of them, so why are you saying there is only one resource
> > > here. It either needs to be changed back to use ARRAY_SIZE, or needs a
> > > comment explaining what magic is in use.
> > because the number of resources depends on the user of rtt
> > we must not hardcode the GPBR reg as this resource will be present only if the
> > rtc-at91sam9 is enabled
> 
> Better would be to leave .num_resources uninitalized and set that
> appropriately elsewhere when you make the decision whether GPBR is
> present or not.  That may help to avoid people trying to "fix" this
> for you via static checking tools.
> 
> As Ryan mentions, a comment in the code would be a good idea too.
the comment is in the drivers code and Kconfig

and will be drop soon in favor of DT

Best Regards,
J.
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