From: Boris Brezillon <boris.brezillon@bootlin.com>
To: Linus Walleij <linus.walleij@linaro.org>,
David Woodhouse <dwmw2@infradead.org>,
Brian Norris <computersforpeace@gmail.com>,
Boris Brezillon <boris.brezillon@free-electrons.com>,
Marek Vasut <marek.vasut@gmail.com>,
Richard Weinberger <richard@nod.at>,
linux-mtd@lists.infradead.org
Cc: Boris Brezillon <boris.brezillon@bootlin.com>
Subject: Re: [2/2,v3] mtd: physmap_of_gemini: Handle pin control
Date: Fri, 7 Dec 2018 10:10:42 +0100 [thread overview]
Message-ID: <20181207091042.17167-1-boris.brezillon@bootlin.com> (raw)
In-Reply-To: <20181127205358.32502-2-linus.walleij@linaro.org>
On Tue, 2018-11-27 at 20:53:58 UTC, Linus Walleij wrote:
> This enables the complex mapping for the Gemini and kicks in
> custom read/write functions that will wrap the existing
> simple functions in calls to enable/disable the parallel
> flash pins using pin controls.
>
> This is necessary on some hardware such as the D-Link
> DIR-685 where all flash pins are patched in/out at the same
> time, but some of the flash pins are in practice unused by
> the flash and have anyway been reused as GPIO.
>
> This concerns specifically CE1 on the Gemini. There is only
> one flash chip, so only CE0 is used, and the line for CE1
> has been reused as chip select for the emulated SPI port
> connected to the display. If we try to use the same lines
> for flash and GPIO at the same time, one of them will loose:
> the GPIO line will disappear because it gets disconnected
> from the pin when the flash group is muxed out.
>
> Fix this by introducing two pin control states named simply
> "enabled" and "disabled" and only enable the flash lines
> when absolutely necessary (during read/write/copy). This
> way, they are available for GPIO at all other times and
> the display works.
>
> Collect all the state variables in a struct named
> struct gemini_flash and allocate this struct at probe
> time.
>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Applied to http://git.infradead.org/linux-mtd.git mtd/next, thanks.
Boris
next prev parent reply other threads:[~2018-12-07 9:11 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-27 20:53 [PATCH 1/2 v3] mtd: maps: Leave assigned complex mappings Linus Walleij
2018-11-27 20:53 ` [PATCH 2/2 v3] mtd: physmap_of_gemini: Handle pin control Linus Walleij
2018-12-07 9:10 ` Boris Brezillon [this message]
2018-12-02 8:47 ` [PATCH 1/2 v3] mtd: maps: Leave assigned complex mappings Boris Brezillon
2018-12-04 13:09 ` Linus Walleij
2018-12-07 9:10 ` [1/2,v3] " Boris Brezillon
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