linux-kernel - Re: [PATCH] ARM: at91: debug: use DEBUG_UART

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Message-ID: <5756ECC5.6020908@atmel.com>
Date:	Tue, 7 Jun 2016 17:48:21 +0200
From:	Nicolas Ferre <nicolas.ferre@...el.com>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
CC:	Russell King <linux@...linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>,
	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: at91: debug: use DEBUG_UART_VIRT

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@...e-electrons.com>

People using their old defconfigs must pay attention to this change...
but it's true that it's a debug configuration anyway...

> ---
>  arch/arm/Kconfig.debug        | 11 ++++++-----
>  arch/arm/include/debug/at91.S | 10 +---------
>  2 files changed, 7 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
> index 19a3dcf5eb2e..2609491f4ab1 100644
> --- a/arch/arm/Kconfig.debug
> +++ b/arch/arm/Kconfig.debug
> @@ -117,15 +117,15 @@ choice
>  		  their output to the serial port on atmel devices.
>  
>  		  SOC                  DEBUG_UART_PHYS   DEBUG_UART_VIRT  PORT
> -		  rm9200, 9260/9g20,   0xfffff200        0xfefff200       DBGU
> +		  rm9200, 9260/9g20,   0xfffff200        0xf8fff200       DBGU
>  		  9261/9g10, 9rl
> -		  9263, 9g45, sama5d3  0xffffee00        0xfeffee00       DBGU
> +		  9263, 9g45, sama5d3  0xffffee00        0xf8ffee00       DBGU
>  		  sama5d4              0xfc00c000        0xfb00c000       USART3
>  		  sama5d4              0xfc069000        0xfb069000       DBGU
>  		  sama5d2              0xf8020000        0xf7020000       UART1
>  
> -		  Please adjust DEBUG_UART_PHYS configuration options based on
> -		  your needs.
> +		  Please adjust DEBUG_UART_PHYS and DEBUG_UART_VIRT
> +		  configuration options based on your needs.
>  
>  	config DEBUG_BCM2835
>  		bool "Kernel low-level debugging on BCM2835 PL011 UART"
> @@ -1627,7 +1627,8 @@ config DEBUG_UART_VIRT
>  		DEBUG_QCOM_UARTDM || DEBUG_S3C24XX_UART || \
>  		DEBUG_S3C64XX_UART || \
>  		DEBUG_BCM63XX_UART || DEBUG_ASM9260_UART || \
> -		DEBUG_SIRFSOC_UART || DEBUG_DIGICOLOR_UA0
> +		DEBUG_SIRFSOC_UART || DEBUG_DIGICOLOR_UA0 || \
> +		DEBUG_AT91_UART
>  
>  config DEBUG_UART_8250_SHIFT
>  	int "Register offset shift for the 8250 debug UART"
> 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?

>  	.endm
>  
>  	.macro	senduart,rd,rx
> 


-- 
Nicolas Ferre