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Subject: Re: [PATCH 2/6] nand_wait : warn if the nand is busy on exit
From: Artem Bityutskiy <dedekind1@gmail.com>
To: Matthieu CASTET <matthieu.castet@parrot.com>
Date: Tue, 28 Jun 2011 10:57:12 +0300
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On Sun, 2011-06-26 at 18:26 +0200, Matthieu CASTET wrote:
> This patch allow to detect buggy driver/hardware with
> bad RnB (dev_ready) management.
> This check cost nothing and could help to detect bugs.
> 
> Signed-off-by: Matthieu CASTET <matthieu.castet@parrot.com>
> ---
>  drivers/mtd/nand/nand_base.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index a3c7fd3..095dfea 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -885,6 +885,8 @@ static int nand_wait(struct mtd_info *mtd, struct nand_chip *chip)
>  	led_trigger_event(nand_led_trigger, LED_OFF);
>  
>  	status = (int)chip->read_byte(mtd);
> +	/* This can happen if in case of timeout or buggy dev_ready */
> +	WARN_ON(!(status & NAND_STATUS_READY));
>  	return status;

This seem to completely miss the chip->dev_ready != NULL case, e.g.,
piece of code above is like this

                while (time_before(jiffies, timeo)) {
                        if (chip->dev_ready) {
                                if (chip->dev_ready(mtd))
                                        break;
                        } else {
                                if (chip->read_byte(mtd) & NAND_STATUS_READY)
                                        break;
                        }
                        cond_resched();
                }

-- 
Best Regards,
Artem Bityutskiy