linux-kernel - Re: [PATCH 2/2] mtd: concat: implement _is

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Date:   Wed, 22 May 2019 21:06:48 +0000
From:   Chris Packham <Chris.Packham@...iedtelesis.co.nz>
To:     Richard Weinberger <richard.weinberger@...il.com>
CC:     David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        "Miquel Raynal" <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] mtd: concat: implement _is_locked mtd operation

On 23/05/19 8:44 AM, Richard Weinberger wrote:
> On Wed, May 22, 2019 at 2:08 AM Chris Packham
> <chris.packham@...iedtelesis.co.nz> wrote:
>>
>> Add an implementation of the _is_locked operation for concatenated mtd
>> devices. As with concat_lock/concat_unlock this can simply use the
>> common helper and pass mtd_is_locked as the operation.
>>
>> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
>> ---
>>   drivers/mtd/mtdconcat.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c
>> index 9514cd2db63c..0e919f3423af 100644
>> --- a/drivers/mtd/mtdconcat.c
>> +++ b/drivers/mtd/mtdconcat.c
>> @@ -496,6 +496,11 @@ static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
>>          return __concat_xxlock(mtd, ofs, len, mtd_unlock);
>>   }
>>
>> +static int concat_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
>> +{
>> +       return __concat_xxlock(mtd, ofs, len, mtd_is_locked);
>> +}
> 
> Hmm, here you start abusing your own new API. :(

Abusing because xxlock is a poor choice of name? I initially had a third 
copy of the logic from lock/unlock which is what lead me to do the 
cleanup first. mtd_lock(), mtd_unlock() and mtd_is_locked() all work the 
same way namely given an offset and a length either lock, unlock or 
return the status of the len/erasesz blocks at ofs.

> 
> Did you verify that the unlock/lock-functions deal correctly with all
> semantics from mtd_is_locked?
> i.e. mtd_is_locked() with len = 0 returns 1 for spi-nor.
> 

I believe so. I've only got access to a parallel NOR flash system that 
uses concatenation and that seems sane  (is mtdconcat able to work with 
spi memories?). The concat_is_locked() should just reflect what the 
underlying mtd device driver returns.