linux-kernel - Re: [PATCH 1/2] mtd: spi-nor: core: Advance erase after the erase cmd has been completed

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Message-ID: <4d4a96d0-1582-400b-b554-14f87df44509@microchip.com>
Date:   Mon, 8 Feb 2021 12:14:19 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <p.yadav@...com>
CC:     <Takahiro.Kuwano@...ineon.com>, <miquel.raynal@...tlin.com>,
        <richard@....at>, <vigneshr@...com>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] mtd: spi-nor: core: Advance erase after the erase cmd
 has been completed

On 2/8/21 1:41 PM, Pratyush Yadav wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On 05/02/21 03:52PM, Tudor Ambarus wrote:
>> Wait for the erase cmd to complete and then advance the erase.
>>
>> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
>> ---
>>  drivers/mtd/spi-nor/core.c | 12 ++++++------
>>  1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
>> index 0522304f52fa..bcaa161bc7db 100644
>> --- a/drivers/mtd/spi-nor/core.c
>> +++ b/drivers/mtd/spi-nor/core.c
>> @@ -1618,12 +1618,12 @@ static int spi_nor_erase_multi_sectors(struct spi_nor *nor, u64 addr, u32 len)
>>                       if (ret)
>>                               goto destroy_erase_cmd_list;
>>
>> -                     addr += cmd->size;
>> -                     cmd->count--;
>> -
>>                       ret = spi_nor_wait_till_ready(nor);
>>                       if (ret)
>>                               goto destroy_erase_cmd_list;
>> +
>> +                     addr += cmd->size;
>> +                     cmd->count--;
>>               }
>>               list_del(&cmd->list);
>>               kfree(cmd);
>> @@ -1704,12 +1704,12 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
>>                       if (ret)
>>                               goto erase_err;
>>
>> -                     addr += mtd->erasesize;
>> -                     len -= mtd->erasesize;
>> -
>>                       ret = spi_nor_wait_till_ready(nor);
>>                       if (ret)
>>                               goto erase_err;
>> +
>> +                     addr += mtd->erasesize;
>> +                     len -= mtd->erasesize;
> 
> Do these changes have any practical benefit? IMO they are worth doing
> even if there is none but I'm curious what prompted this patch.

I saw these when reviewing Takahiro's patches. Addr and len were gratuitously 
updated even when the wait failed. We'll avoid 2 extra ops on the error path.
Plus, having them updated before the wait can be misleading for someone that
tracks them down with some debug messages. I find the code better structured,
and the code will make more sense when it is read, if using this patch.

> 
> Reviewed-by: Pratyush Yadav <p.yadav@...com>

Thanks,
ta
> 
>>               }
>>
>>       /* erase multiple sectors */
> 
> --
> Regards,
> Pratyush Yadav
> Texas Instruments Inc.
>