From: Boris Brezillon <boris.brezillon@collabora.com>
To: Tomer Maimon <tmaimon77@gmail.com>, vigneshr@ti.com
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>,
bbrezillon@kernel.org, richard@nod.at,
tudor.ambarus@microchip.com,
Schrempf Frieder <frieder.schrempf@kontron.de>,
linux-spi@vger.kernel.org, broonie@kernel.org,
linux-mtd@lists.infradead.org, miquel.raynal@bootlin.com
Subject: Re: [RFC v1 0/3] *spi-mem: adding setup and callback function
Date: Tue, 30 Jul 2019 08:54:38 +0200 [thread overview]
Message-ID: <20190730085438.6fe0480b@collabora.com> (raw)
In-Reply-To: <CAP6Zq1iPXDX_Gtz6ZWYm3JoHgHjdapotVLGw-Lq4tc2X-6eAug@mail.gmail.com>
Trimmed the recipient list a bit and used Frieder's new address.
+Sergey
On Mon, 29 Jul 2019 23:55:05 +0300
Tomer Maimon <tmaimon77@gmail.com> wrote:
> Hi Boris,
>
> Thanks for the prompt reply,
>
>
>
> On Mon, 29 Jul 2019 at 18:29, Boris Brezillon <boris.brezillon@collabora.com>
> wrote:
>
> > Hi Tomer,
> >
> > On Mon, 29 Jul 2019 17:25:01 +0300
> > Tomer Maimon <tmaimon77@gmail.com> wrote:
> >
> > > Lately we have working on Flash interface unit (FIU) SPI driver that
> > > using spi-mem interface, Our FIU HW module support direct Flash Rd//Wr.
> > >
> > > In our SOC (32 bit dual core ARM) we have 3 FIU's that using memory
> > mapping as follow:
> > >
> > > FIU0 - have 2 chip select and each one have 128MB memory mapping (total
> > 256MB memory mapping)
> > > FIU1 - have 4 chip select and each one have 128MB memory mapping (total
> > 512MB memory mapping)
> > > FIU2 - have 4 chip select and each one have 16MB memory mapping (total
> > 32MB memory mapping)
> > >
> > > Totally 800MB memory mapping.
> > >
> > > When the FIU driver probe it don't know the size of each Flash that
> > > connected to the FIU, so the entire memory mapping is allocated for each
> > FIU
> > > according the FIU device tree memory map parameters.
> >
> > Do you need those mappings to be active to support simple reg accesses?
> >
> > > It means, if we enable all three FIU's the drivers will try to allocate
> > totally 800MB.
> > >
> > > In 32bit system it is problematic because the kernel have only 1GB
> > > of memory allocation so the vmalloc cannot take 800MB.
> > >
> > > When implementing the FIU driver in the mtd/spi-nor we allocating memory
> > address only
> > > for detected Flash with exact size (usually we are not using 128MB
> > Flash), and in that case usually we allocating much less memory.
> > >
> > > To solve this issue we needed to overcome two things:
> > >
> > > 1. Get argument from the upper layer (spi-mem layer)
> > > 2. Calling the get argument function after SPI_NOR_SCAN function.
> > (the MTD Flash size filled in SPI_NOR_SCAN function)
> >
> > That's clearly breaking the layering we've tried to restore with the
> > spi-nor/spi-mem split, and I don't see why this is needed since we now
> > have a way to create direct mappings dynamically (with the dirmap API).
> > Have you tried implementing the dirmap hooks in your driver?
>
>
> Sorry but I wasn't familiar with the direct mapping in the spi-mem, it
> seems it needed to implemented in the m25p80 driver as well, am I correct?
There's this patch [1] floating around. IIRC, Sergey was waiting for
the m25p80 -> spi-nor merge to send a v5. Vignesh, any updates on that
one? If you don't have time to work on that, maybe Sergey could send a
v5.
[1]https://www.spinics.net/lists/linux-mtd/msg07358.html
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next prev parent reply other threads:[~2019-07-30 6:55 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-29 14:25 [RFC v1 0/3] *spi-mem: adding setup and callback function Tomer Maimon
2019-07-29 14:25 ` [RFC v1 1/3] spi: spi-mem: add spi-mem setup function Tomer Maimon
2019-07-29 14:25 ` [RFC v1 2/3] spi: spi-mem: add callback function to spi-mem device Tomer Maimon
2019-07-29 14:25 ` [RFC v1 3/3] mtd: m25p80: add get Flash size callback support Tomer Maimon
2019-07-29 15:28 ` [RFC v1 0/3] *spi-mem: adding setup and callback function Boris Brezillon
[not found] ` <CAP6Zq1iPXDX_Gtz6ZWYm3JoHgHjdapotVLGw-Lq4tc2X-6eAug@mail.gmail.com>
2019-07-30 6:54 ` Boris Brezillon [this message]
2019-07-30 16:53 ` Sergei Shtylyov
2019-07-30 17:48 ` Vignesh Raghavendra
2019-07-30 18:04 ` Boris Brezillon
[not found] ` <CAP6Zq1hfVoS8+VU0rAtKAX7D22qTVHDMosiCRMKV8sQB_m0qOQ@mail.gmail.com>
2019-08-01 6:42 ` Vignesh Raghavendra
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