linux-kernel - Re: [PATCH RFC 2/3] mtd: rawnand: Add support Macronix Block Protection function

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Date:   Mon, 21 Oct 2019 16:40:57 +0800
From:   masonccyang@...c.com.tw
To:     "Boris Brezillon" <boris.brezillon@...labora.com>
Cc:     bbrezillon@...nel.org, computersforpeace@...il.com,
        dwmw2@...radead.org, frieder.schrempf@...tron.de,
        gregkh@...uxfoundation.org, juliensu@...c.com.tw,
        linux-kernel@...r.kernel.org, linux-mtd@...ts.infradead.org,
        marcel.ziswiler@...adex.com, marek.vasut@...il.com,
        "Miquel Raynal" <miquel.raynal@...tlin.com>, richard@....at,
        tglx@...utronix.de, vigneshr@...com
Subject: Re: [PATCH RFC 2/3] mtd: rawnand: Add support Macronix Block Protection
 function


Hi Boris,

 
> > > > > > Then fill-in these two hooks from the manufacturer code, 
without 
> > the
> > > > > > postponed init.
> > > > > > 
> > > > > 
> > > > > But in the final of nand_scan_tail(), mtd->_lock/_unlock will be
> > > > > filled by NULL, right ? 
> > > > 
> > > > The NAND core should set mtd->_lock/_unlock() to NAND specific 
hooks 
> > so
> > > > that the MTD layer is abstracted and and drivers do not see it. 
Then,
> > > > in the NAND helper, either there is no specific hook defined by a
> > > > manufacturer driver and you return -ENOTSUPP, or you execute the
> > > > defined hook. 
> > > 
> > > okay, patch specific manufacturer _lock/_unlock driver
> > > in nand_manufacturer_init();
> > > 
> > > and in the final of nand_scan_tail()
> > > if (!mtd->_lock)
> > >  mtd->_lock = NULL;
> > > if (!mtd->_unlock)
> > >  mtd->_unlock = NULL; 
> > 
> > 
> > I'm still considering of post_init() in nand_scan_tail() for
> > MTD layer default call-back function replacement because
> > there would be more call-back functions need it.
> > i.e., 
> > MTD->_lock/_unlokc
> > MTD->_suspend/_resume
> 
> Again, that's something that needs to be abstracted so that both the
> NAND manufacturer driver and the NAND controller driver can take
> appropriate actions on suspend/resume operations.
> 
> > NTD->_point/_unpoint
> 
> ->_point/_unpoint() are irrelevant for a NAND chip.
> 
> > ...
> > 
> > 
> > actually, my patch series are including MTD->_locl/_unlock and 
> > MTD->_suspend/_resume. how do you think ?
> 
> Miquel was suggesting to add nand_chip->{lock,unlock,is_locked}()
> methods that would be implemented by the NAND manufacturer drivers, and
> have generic wrappers implemented in nand_base.c:
> 
> static int nand_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
> {
>    struct nand_chip *chip = mtd_to_nand(mtd);
> 
>    if (!chip->lock)
>       return -ENOTSUPP;
> 
>    return chip->lock(chip, ofs, len);
> }
> 
> ...
> 
> If you do that, you won't need this post_init() hook.

got it, but ... 
user space program flash_lock/flash_unlock are calling 
mtd_lock() & mtd_unlock().
i.e.,
int mtd_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
         if (!mtd->_lock)
                 return -EOPNOTSUPP;
         if (ofs < 0 || ofs >= mtd->size || len > mtd->size - ofs)
                 return -EINVAL;
         if (!len)
                 return 0;
         return mtd->_lock(mtd, ofs, len);
}


thanks for your time & comments.
Mason


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