linux-kernel - Re: [PATCH 4/5] ARM: socfpga: Enable Arria10 L2 cache ECC on startup

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Date:	Sat, 5 Mar 2016 00:36:16 -0600
From:	Dinh Nguyen <dinguyen@...nsource.altera.com>
To:	<tthayer@...nsource.altera.com>
CC:	<bp@...en8.de>, <dougthompson@...ssion.com>,
	<m.chehab@...sung.com>, <robh+dt@...nel.org>, <pawel.moll@....com>,
	<mark.rutland@....com>, <ijc+devicetree@...lion.org.uk>,
	<galak@...eaurora.org>, <linux@....linux.org.uk>,
	<grant.likely@...aro.org>, <devicetree@...r.kernel.org>,
	<linux-doc@...r.kernel.org>, <linux-edac@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <tthayer.linux@...il.com>
Subject: Re: [PATCH 4/5] ARM: socfpga: Enable Arria10 L2 cache ECC on
 startup

On Tue, 1 Mar 2016, tthayer@...nsource.altera.com wrote:

> From: Thor Thayer <tthayer@...nsource.altera.com>
> 
> Enable ECC for Arria10 L2 cache on machine startup. The ECC has to be
> enabled before data is stored in memory otherwise the ECC will fail
> on reads.
> 
> Signed-off-by: Thor Thayer <tthayer@...nsource.altera.com>
> ---
>  arch/arm/mach-socfpga/l2_cache.c |   42 ++++++++++++++++++++++++++++++++++----
>  1 file changed, 38 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/mach-socfpga/l2_cache.c b/arch/arm/mach-socfpga/l2_cache.c
> index e3907ab..b197218 100644
> --- a/arch/arm/mach-socfpga/l2_cache.c
> +++ b/arch/arm/mach-socfpga/l2_cache.c
> @@ -17,14 +17,31 @@
>  #include <linux/of_platform.h>
>  #include <linux/of_address.h>
>  
> +#include "core.h"
> +
> +/* A10 System Manager ECC interrupt mask control registers */
> +#define A10_L2_ECC_CTRL_OFST            0x0
> +
> +#define A10_SYSMGR_ECC_INTMASK_CLR_OFST 0x98
> +#define A10_L2_ECC_INT_CLR_OFST         0xA8
> +
> +#define A10_MPU_CTRL_L2_ECC_EN          BIT(0)
> +#define A10_ECC_INTMASK_CLR_EN          BIT(0)
> +#define A10_ECC_INT_CLR                 (BIT(31) | BIT(15))
> +
>  void socfpga_init_l2_ecc(void)
>  {
>  	struct device_node *np;
>  	void __iomem *mapped_l2_edac_addr;
> +	const char *compat = "altr,socfpga-l2-ecc";
>  
> -	np = of_find_compatible_node(NULL, NULL, "altr,socfpga-l2-ecc");
> +	if (of_machine_is_compatible("altr,socfpga-arria10"))
> +		compat = "altr,socfpga-a10-l2-ecc";

The ARM maintainers have made comment to me about about trying to not sprinkle
these of_machine_is_compatible() all over the place. You should make the
decision during the initial probe of the machine. Please look at how the
.restart is differentiate between the 2 platforms.


> +
> +	/* Find the L2 EDAC device tree node */
> +	np = of_find_compatible_node(NULL, NULL, compat);
>  	if (!np) {
> -		pr_err("Unable to find socfpga-l2-ecc in dtb\n");
> +		pr_err("Unable to find %s in dtb\n", compat);
>  		return;
>  	}
>  
> @@ -35,7 +52,24 @@ void socfpga_init_l2_ecc(void)
>  		return;
>  	}
>  
> -	/* Enable ECC */
> -	writel(0x01, mapped_l2_edac_addr);
> +	if (of_machine_is_compatible("altr,socfpga-arria10")) {

Same comment as above here.

BR,
Dinh