From: Mark Brown <broonie@kernel.org>
To: "Jonathan Neuschäfer" <j.neuschaefer@gmx.net>
Cc: linux-spi@vger.kernel.org, openbmc@lists.ozlabs.org,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/3] spi: wpcm-fiu: Add driver for Nuvoton WPCM450 Flash Interface Unit (FIU)
Date: Fri, 25 Nov 2022 16:48:23 +0000 [thread overview]
Message-ID: <Y4Dx13KQHqyBLak3@sirena.org.uk> (raw)
In-Reply-To: <Y4DuW6Rai0urvrEI@probook>
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On Fri, Nov 25, 2022 at 05:33:31PM +0100, Jonathan Neuschäfer wrote:
> As to connecting non-memory chips: There is also a second, completely
> different SPI controller in this SoC, which is used on some boards (in
> factory configuration) to drive a little status LCD. I think it would be
> easiest to use that one for custom hardware extensions.
That's never stopped hardware engineers. Perhaps it's simpler for
pinmuxing, layout or other reasons in a given design.
> > If the driver were implementing regular SPI operations and advertising
> > a maximum transfer length this should just work without having to jump
> > through hoops. The core can split transfers up into sections that fit
> > within the controller limits transparently.
> As far as I'm aware, the controller is not capable of performing a pure
> read transfer, because the command byte (a byte that is written, in
> half-duplex) is always included at the start. I think this limitation
> would break your idea.
> IOW, the hoops aren't nice, but I think they're necessary.
Ah, I see. That is very limiting. I'm very surprised that the
6 byte thing works at all TBH.
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next prev parent reply other threads:[~2022-11-25 16:50 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-24 19:13 [PATCH v2 0/3] Nuvoton WPCM450 FIU SPI flash controller Jonathan Neuschäfer
2022-11-24 19:13 ` [PATCH v2 1/3] dt-bindings: spi: Add Nuvoton WPCM450 Flash Interface Unit (FIU) Jonathan Neuschäfer
2022-11-25 8:33 ` Krzysztof Kozlowski
2022-11-25 13:13 ` Mark Brown
2022-11-25 14:33 ` Jonathan Neuschäfer
2022-11-26 22:25 ` Rob Herring
2022-11-28 11:05 ` Conor Dooley
2022-11-28 13:58 ` Jonathan Neuschäfer
2022-11-28 14:09 ` Conor Dooley
2022-11-28 17:57 ` Mark Brown
2022-11-24 19:13 ` [PATCH v2 2/3] spi: wpcm-fiu: Add driver for " Jonathan Neuschäfer
2022-11-25 13:04 ` Mark Brown
2022-11-25 16:33 ` Jonathan Neuschäfer
2022-11-25 16:48 ` Mark Brown [this message]
2022-11-24 19:14 ` [PATCH v2 3/3] spi: wpcm-fiu: Add direct map support Jonathan Neuschäfer
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