Re: [PATCH v2 01/10] mtd: cfi_cmdset_0002: Change do_write_oneword() to use chip_good()

[Chris Packham <Chris.Packham@xxxxxxxxxxxxxxxxxxx>]

On 20/10/18 5:55 AM, Tokunori Ikegami wrote:
> This is required for OpenWrt Project to result the flash write issue as
> below patche.
> <https://git.openwrt.org/?p=openwrt/openwrt.git;a=commitdiff;h=ddc11c3932c7b7b7df7d5fbd48f207e77619eaa7>
> 
> Also the original patch in OpenWRT is below.
> <https://github.com/openwrt/openwrt/blob/v18.06.0/target/linux/ar71xx/patches-4.9/403-mtd_fix_cfi_cmdset_0002_status_check.patch>
> 
> So change to use chip_good() instead of chip_ready().
> 
> The reason to use chip_good() is that just actually fix the issue.
> And also in the past I had fixed the erase function also as same way by the
> patch below.
>    <https://patchwork.ozlabs.org/patch/922656/>
>      Note: The reason for the patch for erase is same.
> 
> In my understanding the chip_ready() is just checked the value twice from
> flash.
> So I think that sometimes incorrect value is read twice and it is depended
> on the flash device behavior but not sure..
> 
> So change to use chip_good() instead of chip_ready().

I think much of this is commentary for readers of the mailing list not 
something that should be in the final commit (i.e. it should be after 
the '---'). The commit message should really reflect what the problem 
was and how this change fixes it.

I think you've got a better handle on what chip_good() does than I do so 
I won't attempt to provide a commit message here.

> Signed-off-by: Tokunori Ikegami <ikegami@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
> Signed-off-by: Koen Vandeputte <koen.vandeputte@xxxxxxxxxxxx>
> Signed-off-by: Fabio Bettoni <fbettoni@xxxxxxxxx>
> Co-Developed-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
> Co-Developed-by: Koen Vandeputte <koen.vandeputte@xxxxxxxxxxxx>
> Co-Developed-by: Fabio Bettoni <fbettoni@xxxxxxxxx>
> Reported-by: Fabio Bettoni <fbettoni@xxxxxxxxx>
> Cc: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
> Cc: Joakim Tjernlund <Joakim.Tjernlund@xxxxxxxxxxxx>
> Cc: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> Cc: linux-mtd@xxxxxxxxxxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> Changes since v1:
> - Just update the commit message.
> 
>   drivers/mtd/chips/cfi_cmdset_0002.c | 18 ++++++++++++------
>   1 file changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
> index 72428b6bfc47..251c9e1675bd 100644
> --- a/drivers/mtd/chips/cfi_cmdset_0002.c
> +++ b/drivers/mtd/chips/cfi_cmdset_0002.c
> @@ -1627,31 +1627,37 @@ static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip,
>   			continue;
>   		}
>   
> -		if (time_after(jiffies, timeo) && !chip_ready(map, adr)){
> +		if (chip_good(map, adr, datum))
> +			break;
> +
> +		if (time_after(jiffies, timeo)){
>   			xip_enable(map, chip, adr);
>   			printk(KERN_WARNING "MTD %s(): software timeout\n", __func__);
>   			xip_disable(map, chip, adr);
> +			ret = -EIO;
>   			break;
>   		}
>   
> -		if (chip_ready(map, adr))
> -			break;
> -
>   		/* Latency issues. Drop the lock, wait a while and retry */
>   		UDELAY(map, chip, adr, 1);
>   	}
> +
>   	/* Did we succeed? */
> -	if (!chip_good(map, adr, datum)) {
> +	if (ret) {
>   		/* reset on all failures. */
>   		map_write(map, CMD(0xF0), chip->start);
>   		/* FIXME - should have reset delay before continuing */
>   
> -		if (++retry_cnt <= MAX_RETRIES)
> +		if (++retry_cnt <= MAX_RETRIES) {
> +			ret = 0;
>   			goto retry;
> +		}
>   
>   		ret = -EIO;
>   	}
> +
>   	xip_enable(map, chip, adr);
> +
>    op_done:
>   	if (mode == FL_OTP_WRITE)
>   		otp_exit(map, chip, adr, map_bankwidth(map));
> 


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