linux-kernel - Re: [PATCH] mtd: spi-nor: Add support for S3AN spi-nor devices

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Message-ID: <20160921101420.7ea87f2d@bbrezillon>
Date:   Wed, 21 Sep 2016 10:14:20 +0200
From:   Boris Brezillon <boris.brezillon@...e-electrons.com>
To:     Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
Cc:     Cyrille Pitchen <cyrille.pitchen@...el.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Javier Martinez Canillas <javier@....samsung.com>,
        Stephen Warren <swarren@...dia.com>,
        Jagan Teki <jteki@...nedev.com>, Vignesh R <vigneshr@...com>,
        Marek Vasut <marex@...x.de>,
        Ezequiel García 
        <ezequiel@...guardiasur.com.ar>,
        Rafał Miłecki <zajec5@...il.com>,
        Furquan Shaikh <furquan@...gle.com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mtd: spi-nor: Add support for S3AN spi-nor devices

On Wed, 21 Sep 2016 09:57:23 +0200
Ricardo Ribalda Delgado <ricardo.ribalda@...il.com> wrote:

> Hi Boris
> 
> On Wed, Sep 21, 2016 at 9:07 AM, Boris Brezillon
> <boris.brezillon@...e-electrons.com> wrote:
> > Hi Ricardo,
> >
> > Please try to pass the version in your subject prefix (pass
> > --subject-prefix="PATCH vX" to git format-patch).
> >  
> 
> Sorry about that.
> 
> 
> > On Tue, 20 Sep 2016 17:45:51 +0200
> > Ricardo Ribalda Delgado <ricardo.ribalda@...il.com> wrote:  
> 
> >>  /*
> >> + * This code converts an address to the Default Address Mode, that has non
> >> + * power of two page sizes. We must support this mode because it is the default
> >> + * mode supported by Xilinx tools, it can access the whole flash area and
> >> + * changing over to the Power-of-two mode is irreversible and corrupts the
> >> + * original data.
> >> + */
> >> +static loff_t spi_nor_s3an_addr_convert(struct spi_nor *nor, unsigned int addr)
> >> +{
> >> +     unsigned int offset;
> >> +
> >> +     offset = (nor->page_size == 264) ? (addr % 264) : (addr % 528);  
> >
> > Can you send a new version with
> >
> >         offset = addr % nor->page_size;
> >
> > to see if kbuild test robot still complains.
> >  
> 
> This code:
> 
> static loff_t spi_nor_s3an_addr_convert(struct spi_nor *nor, loff_t addr)
> {
> unsigned int offset;
> 
> offset = addr % nor->page_size;
> 
> return ((addr - offset) << 1) | offset;
> }
> 
> 
> When built like:
> 
>    wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross
> -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # save the attached .config to linux build tree
>         make.cross ARCH=blackfin
> 
> Produces this error:
> 
> 
> drivers/built-in.o: In function `spi_nor_write':
> drivers/mtd/spi-nor/spi-nor.c:(.text+0xfeb8): undefined reference to `__moddi3'
> drivers/built-in.o: In function `spi_nor_read':
> drivers/mtd/spi-nor/spi-nor.c:(.text+0x10248): undefined reference to `__moddi3'
> drivers/built-in.o: In function `spi_nor_erase':
> drivers/mtd/spi-nor/spi-nor.c:(.text+0x1034e): undefined reference to `__moddi3'
> Makefile:956: recipe for target 'vmlinux' failed
> 
> 
> But I think I found the right combination:
> 
> 
> static loff_t spi_nor_s3an_addr_convert(struct spi_nor *nor, loff_t addr)
> {
> unsigned int offset = addr;
> 
> offset %= nor->page_size;
> 
> return ((addr - offset) << 1) | offset;
> }
> 
> 
> This one works fine on x86 and blackfin
> 
> Sending v7

Wait. If you really want to manipulate an loff_t variable, you can do

	offset = do_div(addr, nor->page_size);