linux-kernel - Re: [PATCH] mtd: nand: mxic-ecc: Fix mxic_ecc_data_xfer_wait_for

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Date:   Wed, 15 Feb 2023 14:09:50 +0100
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-mtd@...ts.infradead.org
Subject: Re: [PATCH] mtd: nand: mxic-ecc: Fix
 mxic_ecc_data_xfer_wait_for_completion() when irq is used

Hi Christophe,

christophe.jaillet@...adoo.fr wrote on Wed, 15 Feb 2023 12:08:45 +0100:

> wait_for_completion_timeout() and readl_poll_timeout() don't handle their
> return value the same way.
> 
> wait_for_completion_timeout() returns 0 on time out (and >0 in all other
> cases)
> readl_poll_timeout() returns 0 on success and -ETIMEDOUT upon a timeout.

That's a shame, but yeah, excellent catch!

> In order for the error handling path to work in both cases, the logic
> against wait_for_completion_timeout() needs to be inverted.
> 
> Fixes: 48e6633a9fa2 ("mtd: nand: mxic-ecc: Add Macronix external ECC engine support")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> Compile tested only.
> 
> This is really spurious.
> If I'm right, this means that it never worked!
> 
> Can any one with the hardware test?

The design I used for development and testing had no interrupt line
available for that IIRC, so I only tested the polling case ('else'
side) and completely overlooked that difference. I might have mentioned
it in the cover letter, if I didn't, it's an oversight.

> ---
>  drivers/mtd/nand/ecc-mxic.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/mtd/nand/ecc-mxic.c b/drivers/mtd/nand/ecc-mxic.c
> index 8afdca731b87..6b487ffe2f2d 100644
> --- a/drivers/mtd/nand/ecc-mxic.c
> +++ b/drivers/mtd/nand/ecc-mxic.c
> @@ -429,6 +429,7 @@ static int mxic_ecc_data_xfer_wait_for_completion(struct mxic_ecc_engine *mxic)
>  		mxic_ecc_enable_int(mxic);
>  		ret = wait_for_completion_timeout(&mxic->complete,
>  						  msecs_to_jiffies(1000));
> +		ret = ret ? 0 : -ETIMEDOUT;
>  		mxic_ecc_disable_int(mxic);
>  	} else {
>  		ret = readl_poll_timeout(mxic->regs + INTRPT_STS, val,


Thanks,
Miquèl