linux-kernel - Re: [RFC PATCH v2 05/12] mtd: rawnand: ams-delta: use GPIO API for data read/write

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Message-ID: <20180807190627.4340aade@bbrezillon>
Date:   Tue, 7 Aug 2018 19:06:27 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Janusz Krzysztofik <jmkrzyszt@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Jonathan Corbet <corbet@....net>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Tony Lindgren <tony@...mide.com>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
        linux-mtd@...ts.infradead.org, linux-doc@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2 05/12] mtd: rawnand: ams-delta: use GPIO API for
 data read/write

On Tue,  7 Aug 2018 00:29:11 +0200
Janusz Krzysztofik <jmkrzyszt@...il.com> wrote:

> Don't readw()/writew() data directly from/to GPIO port which is under
> control of gpio-omap driver, use GPIO API instead.
> 
> Degrade of performance on Amstrad Delta is completely not acceptable.

Can we have numbers along with information about where the overhead is
when using gpiod_{get,set}_raw_array_value()?

> 
> The driver should work with any 8+-bit bidirectional GPIO port, not
> only OMAP.

That's cool!