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From: Alexandre Belloni <alexandre.belloni@free-electrons.com>
To: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Russell King <linux@armlinux.org.uk>,
	Arnd Bergmann <arnd@arndb.de>,
	Boris Brezillon <boris.brezillon@free-electrons.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ARM: at91: debug: use DEBUG_UART_VIRT
Date: Tue, 7 Jun 2016 18:23:01 +0200	[thread overview]
Message-ID: <20160607162301.GL3363@piout.net> (raw)
In-Reply-To: <5756ECC5.6020908@atmel.com>

On 07/06/2016 at 17:48:21 +0200, Nicolas Ferre wrote :
> Le 07/06/2016 17:24, Alexandre Belloni a écrit :
> > AT91 still uses an offset (0x0100 0000) from the physical address to map
> > the debug UART. This is unfortunate as for some platforms (sama5d3 and
> > earlier), it ends up in the PCI zone and PCI is enabled in multi_v7.
> > Switch to DEBUG_UART_VIRT to solve that.
> > 
> > Tested on sama5d3 and 9g20.
> > 
> > Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> 
> People using their old defconfigs must pay attention to this change...
> but it's true that it's a debug configuration anyway...
> 

I really doubt people are letting DEBUG_LL enabled in a production
kernel...

> > diff --git a/arch/arm/include/debug/at91.S b/arch/arm/include/debug/at91.S
> > index d4ae3b8e2426..0098401e5aeb 100644
> > --- a/arch/arm/include/debug/at91.S
> > +++ b/arch/arm/include/debug/at91.S
> > @@ -9,14 +9,6 @@
> >   *
> >  */
> >  
> > -#ifdef CONFIG_MMU
> > -#define AT91_IO_P2V(x) ((x) - 0x01000000)
> > -#else
> > -#define AT91_IO_P2V(x) (x)
> > -#endif
> > -
> > -#define AT91_DEBUG_UART_VIRT AT91_IO_P2V(CONFIG_DEBUG_UART_PHYS)
> > -
> >  #define AT91_DBGU_SR		(0x14)	/* Status Register */
> >  #define AT91_DBGU_THR		(0x1c)	/* Transmitter Holding Register */
> >  #define AT91_DBGU_TXRDY		(1 << 1)	/* Transmitter Ready */
> > @@ -24,7 +16,7 @@
> >  
> >  	.macro	addruart, rp, rv, tmp
> >  	ldr	\rp, =CONFIG_DEBUG_UART_PHYS		@ System peripherals (phys address)
> > -	ldr	\rv, =AT91_DEBUG_UART_VIRT		@ System peripherals (virt address)
> > +	ldr	\rv, =CONFIG_DEBUG_UART_VIRT		@ System peripherals (virt address)
> 
> Shouldn't we protect the use of this defined value with some
> #warning "Beware the value CONFIG_DEBUG_UART_VIRT haven't been defined:
> is it intentional"
> or even #error?
> 
> or something like that?
> 

Well, those that are using this feature are supposed to know what they
are doing. There is now protection for CONFIG_DEBUG_UART_PHYS anyway.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

  reply	other threads:[~2016-06-07 16:23 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-07 15:24 Alexandre Belloni
2016-06-07 15:48 ` Nicolas Ferre
2016-06-07 16:23   ` Alexandre Belloni [this message]
2016-06-08  7:17     ` Nicolas Ferre
2016-06-08  8:18       ` Nicolas Ferre
2016-06-10 15:10 ` Alexandre Belloni

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