linux-kernel - Re: [PATCH v3 2/5] mtd: rawnand: brcmnand: Fix potential false time out warning

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Date:   Tue, 4 Jul 2023 17:21:41 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     William Zhang <william.zhang@...adcom.com>
Cc:     Broadcom Kernel List <bcm-kernel-feedback-list@...adcom.com>,
        Linux MTD List <linux-mtd@...ts.infradead.org>,
        f.fainelli@...il.com, rafal@...ecki.pl, kursad.oney@...adcom.com,
        joel.peshkin@...adcom.com, computersforpeace@...il.com,
        anand.gore@...adcom.com, dregan@...l.com, kamal.dasu@...adcom.com,
        tomer.yacoby@...adcom.com, dan.beygelman@...adcom.com,
        Florian Fainelli <florian.fainelli@...adcom.com>,
        linux-kernel@...r.kernel.org,
        Vignesh Raghavendra <vigneshr@...com>,
        Richard Weinberger <richard@....at>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Kamal Dasu <kdasu.kdev@...il.com>
Subject: Re: [PATCH v3 2/5] mtd: rawnand: brcmnand: Fix potential false time
 out warning

Hi William,

william.zhang@...adcom.com wrote on Tue, 27 Jun 2023 12:37:35 -0700:

> If system is busy during the command status polling function, the driver
> may not get the chance to poll the status register till the end of time
> out and return the premature status.  Do a final check after time out
> happens to ensure reading the correct status.
> 
> Fixes: 9d2ee0a60b8b ("mtd: nand: brcmnand: Check flash #WP pin status before nand erase/program")
> Signed-off-by: William Zhang <william.zhang@...adcom.com>
> Reviewed-by: Florian Fainelli <florian.fainelli@...adcom.com>

Cc: stable here and in patch 1 as well.

> ---
> 
> Changes in v3: None
> Changes in v2: None
> 
>  drivers/mtd/nand/raw/brcmnand/brcmnand.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> index 69709419516a..37c2c7cfa00e 100644
> --- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> @@ -1080,6 +1080,14 @@ static int bcmnand_ctrl_poll_status(struct brcmnand_controller *ctrl,
>  		cpu_relax();
>  	} while (time_after(limit, jiffies));
>  
> +	/*
> +	 * do a final check after time out in case CPU is busy and driver does
> +	 * not get the enough time to poll to avoid false alarm

Do a final... ...the CPU was busy and the driver did not get enough
time to perform the polling to avoid false alarms.

> +	 */
> +	val = brcmnand_read_reg(ctrl, BRCMNAND_INTFC_STATUS);
> +	if ((val & mask) == expected_val)
> +		return 0;
> +
>  	dev_warn(ctrl->dev, "timeout on status poll (expected %x got %x)\n",
>  		 expected_val, val & mask);
>  

Otherwise looks good.

Thanks,
Miquèl