Messages in this thread | | | Date | Wed, 26 Nov 2008 11:09:49 +0200 | From | Paulius Zaleckas <> | Subject | Re: [RFC 2.6.27 1/1] gpiolib: add support for batch set of pins |
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Jaya Kumar wrote: > Beloved friends, > > I would like to request your feedback on the following idea. I hope I have > made sure to CC all the right people and the right lists! If not, PLEASE > let me know! I couldn't find a MAINTAINERS entry for gpiolib so I just > used what I saw in the git log and have also added people and lists that > I think may be interested. > > This is just an RFC. If you all feel it is looking like the right approach > then I'll clean it up and make it a patch. > > Thanks, > jaya > > am300epd was doing 800*600*16*gpio_set_value for each framebuffer transfer > (it uses 16-pins of gpio as its data bus). I found this caused a wee > performance limitation. This patch adds an API for gpio_set_value_bus > which allows users to set batches of consecutive gpio together in a single > call. I have done a test implementation on gumstix (pxa255) with am300epd > and it provides a nice improvement in performance. > > Signed-off-by: Jaya Kumar <jayakumar.lkml@gmail.com> > Cc: David Brownell <dbrownell@users.sourceforge.net> > Cc: David Brownell <david-b@pacbell.net> > Cc: Sam Ravnborg <sam@ravnborg.org> > Cc: Jean Delvare <khali@linux-fr.org> > Cc: Eric Miao <eric.miao@marvell.com> > Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> > Cc: Philipp Zabel <philipp.zabel@gmail.com> > Cc: Russell King <rmk@arm.linux.org.uk> > Cc: Ben Gardner <bgardner@wabtec.com> > CC: Greg KH <greg@kroah.com> > Cc: linux-arm-kernel@lists.arm.linux.org.uk > Cc: linux-fbdev-devel@lists.sourceforge.net > Cc: linux-kernel@vger.kernel.org > > --- > arch/arm/mach-pxa/am300epd.c | 9 ++++++ > arch/arm/mach-pxa/gpio.c | 28 +++++++++++++++++++++ > arch/arm/mach-pxa/include/mach/gpio.h | 24 ++++++++++++++++++ > drivers/gpio/gpiolib.c | 44 +++++++++++++++++++++++++++++++++ > include/asm-generic/gpio.h | 6 ++++ > 5 files changed, 111 insertions(+), 0 deletions(-) >
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> diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h > index 81797ec..9747517 100644 > --- a/include/asm-generic/gpio.h > +++ b/include/asm-generic/gpio.h > @@ -44,6 +44,8 @@ struct module; > * returns either the value actually sensed, or zero > * @direction_output: configures signal "offset" as output, or returns error > * @set: assigns output value for signal "offset" > + * @set_bus: batch assigns output values for consecutive signals starting at > + * "offset" with width in bits "bitwidth" > * @to_irq: optional hook supporting non-static gpio_to_irq() mappings; > * implementation may not sleep > * @dbg_show: optional routine to show contents in debugfs; default code > @@ -84,6 +86,9 @@ struct gpio_chip { > unsigned offset, int value); > void (*set)(struct gpio_chip *chip, > unsigned offset, int value); > + void (*set_bus)(struct gpio_chip *chip, > + unsigned offset, int values,
I think values should be unsigned
> + int bitwidth); > > int (*to_irq)(struct gpio_chip *chip, > unsigned offset); > @@ -124,6 +129,7 @@ extern void gpio_set_value_cansleep(unsigned gpio, int value); > */ > extern int __gpio_get_value(unsigned gpio); > extern void __gpio_set_value(unsigned gpio, int value); > +extern void __gpio_set_value_bus(unsigned gpio, int values, int bitwidth); > > extern int __gpio_cansleep(unsigned gpio); >
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