From: Chris Brandt <Chris.Brandt@renesas.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: Mark Brown <broonie@kernel.org>, Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>,
linux-spi <linux-spi@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
linux-clk <linux-clk@vger.kernel.org>,
Mason Yang <masonccyang@mxic.com.tw>
Subject: RE: [PATCH v2 2/6] dt-bindings: spi: Document Renesas SPIBSC bindings
Date: Tue, 10 Dec 2019 20:33:34 +0000 [thread overview]
Message-ID: <TY1PR01MB1562D812E6060516E689C7578A5B0@TY1PR01MB1562.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <CAMuHMdUOUctfD7K21yAx8QFAj0LP+D2PrMCri8H2PMUr5WzXoQ@mail.gmail.com>
On Tue, Dec 10, 2019, Geert Uytterhoeven wrote:
> > > The second one is not needed, if you would add "ranges" for the
> > > memory-mapped mode.
> >
> > I'm not sure we can do that. The flash bus is accessed via a window
> > with the high bits in the DREAR reg, even in the direct read mode...
>
> So if the FLASH is too large, you cannot access all of it without programming
> the high bits.
> However, when using XIP, you're limited to the window size anyway.
If your SPI flash supports 32-bit address commands, ("4READ" for
example) then all 32-bit are sent out.
The 'high bits' that he's talking about is for accessing SPI that is
beyond the XIP window size.
For example, the RZ/A1 has 64MB window size (RZ/A2=256MB). Meaning
anything above 64MB is not accessible.
However, you could program this register to basically change the window
starting point and make the upper 64MB of a 128MB flash visible and the
lower 64MB portion hidden.
For an XIP system, this is one way of doing a remote firmware update
and keeping the old copy around just in case you need to revert back.
Anyway, the point is this doesn't matter in either the MTD/SPI or
MTD/ROM operation of the driver as far as I can see.
Chris
next prev parent reply other threads:[~2019-12-10 20:33 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-06 13:41 [PATCH v2 0/6] spi: Add Renesas SPIBSC controller Chris Brandt
2019-12-06 13:41 ` [PATCH v2 1/6] spi: Add SPIBSC driver Chris Brandt
2019-12-12 19:36 ` Sergei Shtylyov
2019-12-12 20:19 ` Chris Brandt
2019-12-13 10:01 ` Geert Uytterhoeven
2019-12-13 14:45 ` Chris Brandt
2019-12-13 14:48 ` Geert Uytterhoeven
2019-12-13 19:37 ` Sergei Shtylyov
2019-12-13 18:36 ` Sergei Shtylyov
2019-12-13 19:40 ` Sergei Shtylyov
2019-12-13 20:43 ` Chris Brandt
2019-12-16 18:47 ` Sergei Shtylyov
2019-12-06 13:41 ` [PATCH v2 2/6] dt-bindings: spi: Document Renesas SPIBSC bindings Chris Brandt
2019-12-09 14:09 ` Geert Uytterhoeven
2019-12-09 15:45 ` Chris Brandt
2019-12-09 19:34 ` Geert Uytterhoeven
2019-12-10 20:07 ` Sergei Shtylyov
2019-12-10 20:17 ` Geert Uytterhoeven
2019-12-10 20:33 ` Chris Brandt [this message]
2019-12-10 20:23 ` Chris Brandt
2019-12-06 13:41 ` [PATCH v2 3/6] clk: renesas: r7s9210: Add SPIBSC clock Chris Brandt
2019-12-06 18:40 ` Sergei Shtylyov
2019-12-06 19:49 ` Chris Brandt
2019-12-20 14:38 ` Geert Uytterhoeven
2019-12-20 14:50 ` Chris Brandt
2019-12-06 13:42 ` [PATCH v2 4/6] ARM: dts: r7s72100: Add SPIBSC devices Chris Brandt
2019-12-06 13:42 ` [PATCH v2 5/6] ARM: dts: r7s9210: Add SPIBSC device Chris Brandt
2019-12-06 13:42 ` [PATCH v2 6/6] ARM: dts: gr-peach: Enable SPIBSC Chris Brandt
2019-12-07 20:28 ` [PATCH v2 0/6] spi: Add Renesas SPIBSC controller Sergei Shtylyov
2019-12-09 15:10 ` Chris Brandt
2019-12-11 19:09 ` Sergei Shtylyov
2019-12-12 14:29 ` Chris Brandt
2019-12-12 15:28 ` Mark Brown
2019-12-12 16:53 ` Chris Brandt
2019-12-12 17:13 ` Mark Brown
2019-12-12 17:25 ` Chris Brandt
2019-12-16 15:21 ` Mark Brown
2019-12-16 20:31 ` Sergei Shtylyov
2019-12-16 22:21 ` Chris Brandt
2019-12-17 19:30 ` Sergei Shtylyov
2019-12-17 20:26 ` Geert Uytterhoeven
2019-12-19 16:57 ` Chris Brandt
2019-12-19 19:01 ` Sergei Shtylyov
2019-12-19 21:04 ` Chris Brandt
2019-12-20 1:45 ` masonccyang
2019-12-20 7:55 ` Geert Uytterhoeven
2019-12-24 16:58 ` Sergei Shtylyov
2019-12-27 0:58 ` Mark Brown
2019-12-17 19:44 ` Sergei Shtylyov
2019-12-18 8:09 ` Boris Brezillon
2019-12-19 16:32 ` Chris Brandt
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