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

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Message-ID: <564ADA21.8070700@simon.arlott.org.uk>
Date:	Tue, 17 Nov 2015 07:41:21 +0000
From:	Simon Arlott <simon@...e.lp0.eu>
To:	Brian Norris <computersforpeace@...il.com>
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

On 17/11/15 00:40, Brian Norris wrote:
> + 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.

It's theoretical (I don't have 4GB+ flash), but the Broadcom version of
the NAND driver does this.

> 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
> 


-- 
Simon Arlott
--
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