linux-kernel - Re: [PATCH v2 06/12] mtd: rawnand: stm32_fmc2: use FMC2_TIMEOUT

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Date:   Mon, 27 Apr 2020 20:22:12 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Christophe Kerello <christophe.kerello@...com>
Cc:     <richard@....at>, <vigneshr@...com>, <lee.jones@...aro.org>,
        <robh+dt@...nel.org>, <mark.rutland@....com>, <tony@...mide.com>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <devicetree@...r.kernel.org>, <marex@...x.de>
Subject: Re: [PATCH v2 06/12] mtd: rawnand: stm32_fmc2: use FMC2_TIMEOUT_MS
 for timeouts

Hi Christophe,

Christophe Kerello <christophe.kerello@...com> wrote on Wed, 15 Apr
2020 17:57:30 +0200:

> This patch removes the constant FMC2_TIMEOUT_US.
> FMC2_TIMEOUT_MS is set to 5 seconds and this constant is used
> each time that we need to wait (except when the timeout value
> is set by the framework)
> 
> Signed-off-by: Christophe Kerello <christophe.kerello@...com>
> ---
>  drivers/mtd/nand/raw/stm32_fmc2_nand.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/stm32_fmc2_nand.c b/drivers/mtd/nand/raw/stm32_fmc2_nand.c
> index ab53314..f159c39 100644
> --- a/drivers/mtd/nand/raw/stm32_fmc2_nand.c
> +++ b/drivers/mtd/nand/raw/stm32_fmc2_nand.c
> @@ -37,8 +37,7 @@
>  /* Max ECC buffer length */
>  #define FMC2_MAX_ECC_BUF_LEN		(FMC2_BCHDSRS_LEN * FMC2_MAX_SG)
>  
> -#define FMC2_TIMEOUT_US			1000
> -#define FMC2_TIMEOUT_MS			1000
> +#define FMC2_TIMEOUT_MS			5000
>  
>  /* Timings */
>  #define FMC2_THIZ			1
> @@ -525,9 +524,9 @@ static int stm32_fmc2_ham_calculate(struct nand_chip *chip, const u8 *data,
>  	u32 sr, heccr;
>  	int ret;
>  
> -	ret = readl_relaxed_poll_timeout(fmc2->io_base + FMC2_SR,
> -					 sr, sr & FMC2_SR_NWRF, 10,
> -					 FMC2_TIMEOUT_MS);
> +	ret = readl_relaxed_poll_timeout_atomic(fmc2->io_base + FMC2_SR,
> +						sr, sr & FMC2_SR_NWRF, 1,
> +						1000 * FMC2_TIMEOUT_MS);

Is the _atomic suffix needed here? If yes it would deserve a separate
patch with Fixes/Stable tags.

>  	if (ret) {
>  		dev_err(fmc2->dev, "ham timeout\n");
>  		return ret;
> @@ -1315,7 +1314,7 @@ static int stm32_fmc2_waitrdy(struct nand_chip *chip, unsigned long timeout_ms)
>  	/* Check if there is no pending requests to the NAND flash */
>  	if (readl_relaxed_poll_timeout_atomic(fmc2->io_base + FMC2_SR, sr,
>  					      sr & FMC2_SR_NWRF, 1,
> -					      FMC2_TIMEOUT_US))
> +					      1000 * FMC2_TIMEOUT_MS))
>  		dev_warn(fmc2->dev, "Waitrdy timeout\n");
>  
>  	/* Wait tWB before R/B# signal is low */

You change the timeouts from 1ms to 5s.

Maybe 5s is a little bit too much IMHO but we don't really care as this
is a timeout. However 1ms is tight. If you are changing this value
because it triggers error (eg. when the machine is loaded), then it is
a fix and should appear like it.

Thanks,
Miquèl