linux-kernel - [RFC RFT PATCH 0/4] gpiolib: speed up GPIO array processing

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Date:   Tue, 21 Aug 2018 01:43:37 +0200
From:   Janusz Krzysztofik <jmkrzyszt@...il.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Jonathan Corbet <corbet@....net>,
        Miguel Ojeda Sandonis <miguel.ojeda.sandonis@...il.com>,
        Peter Korsgaard <peter.korsgaard@...co.com>,
        Peter Rosin <peda@...ntia.se>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Kishon Vijay Abraham I <kishon@...com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, linux-gpio@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-mmc@...r.kernel.org, netdev@...r.kernel.org,
        linux-iio@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        Janusz Krzysztofik <jmkrzyszt@...il.com>
Subject: [RFC RFT PATCH 0/4] gpiolib: speed up GPIO array processing


This series is a follow up of the former "mtd: rawnand: ams-delta: Use
gpio-omap accessors for data I/O" which already contained some changes
to gpiolib.  Those previous attempts were commented by Borris Brezillon
who suggested using GPIO API modified to accept bitmaps, and by Linus
Walleij who suggested still more great ideas for further immprovement
of the proposed API changes - thanks!

The goal is to boost performans of get/set array functions while
processing GPIO arrays which represent pins of a signle chip in
hardware order.  If resulting performance is close to PIO, GPIO API
can be used for data I/O without much loss of speed.

Created and tested on a low end Amstrad Delta board with NAND driver
updated to use GPIO API for data I/O.  Performance degrade compared to
PIO is much better than before the optimization but still not quite
satisfactory.


Janusz Krzysztofik (4):
      gpiolib: Pass bitmaps, not integer arrays, to get/set array
      gpiolib: Identify arrays matching GPIO hardware
      gpiolib: Pass array info to get/set array functions
      gpiolib: Implement fast processing path in get/set array


 Documentation/driver-api/gpio/board.rst     |   15 +
 Documentation/driver-api/gpio/consumer.rst  |   48 +++-
 drivers/auxdisplay/hd44780.c                |   64 +++---
 drivers/bus/ts-nbus.c                       |   25 --
 drivers/gpio/gpio-max3191x.c                |   23 +-
 drivers/gpio/gpiolib.c                      |  279 ++++++++++++++++++++++------
 drivers/gpio/gpiolib.h                      |   15 +
 drivers/i2c/muxes/i2c-mux-gpio.c            |    5 
 drivers/mmc/core/pwrseq_simple.c            |   15 -
 drivers/mux/gpio.c                          |    7 
 drivers/net/phy/mdio-mux-gpio.c             |    5 
 drivers/pcmcia/soc_common.c                 |   14 -
 drivers/phy/motorola/phy-mapphone-mdm6600.c |   21 +-
 drivers/staging/iio/adc/ad7606.c            |   12 -
 drivers/tty/serial/serial_mctrl_gpio.c      |    9 
 include/linux/gpio/consumer.h               |   35 ++-
 16 files changed, 410 insertions(+), 182 deletions(-)