From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Brian Norris <computersforpeace@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
MTD Maling List <linux-mtd@lists.infradead.org>,
Boris BREZILLON <boris.brezillon@free-electrons.com>,
Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>,
Linux-sh list <linux-sh@vger.kernel.org>,
Magnus Damm <magnus.damm@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Simon Horman <horms@verge.net.au>,
Frans Klaver <fransklaver@gmail.com>,
David Woodhouse <dwmw2@infradead.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] mtd: sh_flctl: pass FIFO as physical address
Date: Thu, 10 Dec 2015 10:02:06 +0100 [thread overview]
Message-ID: <CAMuHMdXjquhLKsby1QZ+U9JN7bVrxX4guPgC0EQuLXJcmVKACw@mail.gmail.com> (raw)
In-Reply-To: <20151210022146.GH144338@google.com>
Hi Brian,
On Thu, Dec 10, 2015 at 3:21 AM, Brian Norris
<computersforpeace@gmail.com> wrote:
> On Tue, Dec 08, 2015 at 05:30:02PM +0100, Geert Uytterhoeven wrote:
>> On Tue, Dec 8, 2015 at 4:38 PM, Arnd Bergmann <arnd@arndb.de> wrote:
>> > By convention, the FIFO address we pass using dmaengine_slave_config
>> > is a physical address in the form that is understood by the DMA
>> > engine, as a dma_addr_t, phys_addr_t or resource_size_t.
>> >
>> > The sh_flctl driver however passes a virtual __iomem address that
>> > gets cast to dma_addr_t in the slave driver. This happens to work
>> > on shmobile because that platform sets up an identity mapping for
>> > its MMIO regions, but such code is not portable to other platforms,
>> > and prevents us from ever changing the platform mapping or reusing
>> > the driver on other architectures like ARM64 that might not have the
>> > mapping.
>>
>> Note that since the removal of (ARM) sh7367/sh7377/sh7372 support, this
>> driver is used on SH only.
>
> It's still available as COMPILE_TEST, so it's still worth fixing.
>
> But really, does anyone use this driver any more?
It's used on the sh7723-based AP-325RXA board.
No idea if anyone is really using it.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2015-12-10 9:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-08 15:38 [PATCH] mtd: sh_flctl: pass FIFO as physical address Arnd Bergmann
2015-12-08 16:30 ` Geert Uytterhoeven
2015-12-10 2:21 ` Brian Norris
2015-12-10 9:02 ` Geert Uytterhoeven [this message]
2015-12-10 9:27 ` Arnd Bergmann
2015-12-19 2:27 ` Brian Norris
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