[PATH v5 0/4] gpiolib: speed up GPIO array processing

Janusz Krzysztofik
2018-08-29T20:48:29Z

The goal is to boost performance 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

Changelog:
v5:
[PATCH v5 1/4] gpiolib: Pass bitmaps, not integer arrays, to get/set
- drivers/i2c/muxes/i2c-mux-gpio.c:
- drop assigment of values to struct gpiomux.values, as recommended
by Peter Rosin - thanks!,
- mark the .values member of the structure as obsolete,
- drivers/mux/gpio.c:
- drop assigment of values to struct mux_gpio.val, also recommended
by Peter Rosin - thanks!,
- merk the .val member of the structure as obsolete,
- drivers/auxdisplay/hd44780.c:
- fix incorrect bitmap size,
- use >>= operator to simplify notation,
both catched by Miguel Ojeda - thanks!,
- add Cc: clauses as well as Acked-by: collected so far.
[PATCH v5 2/4] gpiolib: Identify arrays matching GPIO hardware
- add Cc: clause.
[PATCH v5 3/4] gpiolib: Pass array info to get/set array functions
- add Cc: clauses as well as Acked-by: collected so far.
[PATCH v5 4/4] gpiolib: Implement fast processing path in get/set
- add Cc: clause.

v4:
That series was 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!

diffstat:
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 | 10 -
drivers/mmc/core/pwrseq_simple.c | 15 -
drivers/mux/gpio.c | 12 -
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, 412 insertions(+), 190 deletions(-)