linux-kernel - Re: [PATCH v2 0/2] eeprom: at25: SPI transfer improvements

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Message-ID: <20190130160839.55f99e63@bbrezillon>
Date:   Wed, 30 Jan 2019 16:08:39 +0100
From:   Boris Brezillon <bbrezillon@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Arnd Bergmann <arnd@...db.de>,
        MTD Maling List <linux-mtd@...ts.infradead.org>,
        Nguyen An Hoan <na-hoan@...so.co.jp>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-spi <linux-spi@...r.kernel.org>
Subject: Re: [PATCH v2 0/2] eeprom: at25: SPI transfer improvements

Hi Greg,

On Wed, 30 Jan 2019 15:50:54 +0100
Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:

> On Tue, Jan 29, 2019 at 08:02:37PM +0100, Geert Uytterhoeven wrote:
> > Hi Boris,
> > 
> > On Fri, Jan 18, 2019 at 11:07 PM Boris Brezillon <bbrezillon@...nel.org> wrote:  
> > > Did you consider converting this driver to spimem? Looks like the
> > > protocol used to communicate with the memory resembles the one used on
> > > SPI NANDs/NORs and fits pretty well in the spi_mem_op representation.
> > >
> > > By doing this conversion you'd allow people to connect an AT25 EEPROM
> > > to an advanced SPI controller that does not support regular SPI
> > > transfers and you wouldn't have to forge SPI messages manually.
> > >
> > > Here is a patch (only compile tested) doing that. The diffstat is not in
> > > favor of this conversion, but I find the resulting code cleaner and more
> > > future proof.  
> > 
> > Thanks, seems to work fine, with the 512-byte 25LC040 I have!
> > 
> > Tested-by: Geert Uytterhoeven <geert+renesas@...der.be>
> > 
> > I did notice that the first two-byte transfer (command+offset) of each
> > message is now split in two one-byte transfers, though.  
> 
> Ok, I'll drop this patch series and wait for the updated version to be
> sent out :)

I'd like to further simplify the patch by using the recently introduced
devm_spi_mem_dirmap_create() function (queued to Mark's spi/for-5.1
branch), which means I'll have to wait v5.1-rc1 before sending a new
version. I'll let you decide if it's worth applying Geert's patches in
the meantime.

Regards,

Boris