linux-kernel - Re: [PATCH] brcmnand: Clear EXT_ADDR error registers in PIO mode

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Message-ID: <20151117004005.GU8456@google.com>
Date:	Mon, 16 Nov 2015 16:40:05 -0800
From:	Brian Norris <computersforpeace@...il.com>
To:	Simon Arlott <simon@...e.lp0.eu>
Cc:	David Woodhouse <dwmw2@...radead.org>,
	linux-mtd@...ts.infradead.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Kevin Cernekee <cernekee@...il.com>,
	bcm-kernel-feedback-list@...adcom.com
Subject: Re: [PATCH] brcmnand: Clear EXT_ADDR error registers in PIO mode

+ bcm-kernel-feedback-list

On Mon, Nov 16, 2015 at 10:05:39PM +0000, Simon Arlott wrote:
> If an error occurs in flash above 4GB in PIO mode then the EXT_ADDR
> registers will be set to the location of the error and never cleared.
> 
> Reset them to 0 before reading.
> 
> Signed-off-by: Simon Arlott <simon@...e.lp0.eu>

Patch looks OK. Did you see this problem in practice, or is this just
theoretical? I thought the documentation seemed to suggest these
registers were cleared together with their non-_EXT counterparts. But
implementation definitely trumps documentation for HW.

Brian

> ---
>  drivers/mtd/nand/brcmnand/brcmnand.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c
> index 12c6190..2c8f67f 100644
> --- a/drivers/mtd/nand/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/brcmnand/brcmnand.c
> @@ -1400,6 +1400,8 @@ static int brcmnand_read_by_pio(struct mtd_info *mtd, struct nand_chip *chip,
>  	/* Clear error addresses */
>  	brcmnand_write_reg(ctrl, BRCMNAND_UNCORR_ADDR, 0);
>  	brcmnand_write_reg(ctrl, BRCMNAND_CORR_ADDR, 0);
> +	brcmnand_write_reg(ctrl, BRCMNAND_UNCORR_EXT_ADDR, 0);
> +	brcmnand_write_reg(ctrl, BRCMNAND_CORR_EXT_ADDR, 0);
>  
>  	brcmnand_write_reg(ctrl, BRCMNAND_CMD_EXT_ADDRESS,
>  			(host->cs << 16) | ((addr >> 32) & 0xffff));
> -- 
> 2.1.4
> 
> -- 
> Simon Arlott
--
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