Re: [PATCH 2/12] pxa: remove the pin configuration from the keypad driver

["eric miao" <eric.y.miao@gmail.com>]

On Jan 29, 2008 7:54 PM, Dmitry Baryshkov <dbaryshkov@gmail.com> wrote:
>
> eric miao wrote:
>
> > On Jan 29, 2008 2:24 PM, Dmitry Torokhov <dtor@insightbb.com> wrote:
> >> Hi Eric,
> >>
> >> On Wednesday 23 January 2008 02:17, eric miao wrote:
> >> > From dbd62bced0f789765d1823f66af792933c6b46a1 Mon Sep 17 00:00:00
> >> > 2001 From: eric miao <eric.miao@marvell.com> Date: Tue, 22 Jan 2008
> >> > 16:34:12 +0800 Subject: [PATCH] pxa: remove the pin configuration
> >> > from the keypad driver
> >> >
> >> > The pin configurations will slowly be moved to the board specific
> >> > code at initialization thus to make the driver more generic.
> >> >
> >> > Signed-off-by: eric miao <eric.miao@marvell.com> ---
> >> >  drivers/input/keyboard/pxa27x_keypad.c   |    4 ----
> >> >  include/asm-arm/arch-pxa/pxa27x_keypad.h |    1 - 2 files changed, 0
> >> >  insertions(+), 5 deletions(-)
> >> >
> >> > diff --git a/drivers/input/keyboard/pxa27x_keypad.c
> >> > b/drivers/input/keyboard/pxa27x_keypad.c index 06c1d5a..43fb63d
> >> > 100644
> >> > --- a/drivers/input/keyboard/pxa27x_keypad.c +++
> >> > b/drivers/input/keyboard/pxa27x_keypad.c @@ -208,10 +208,6 @@ static
> >> > int __devinit pxa27x_keypad_probe(struct platform_device *pdev)
> >> >       if (error)
> >> >               goto err_free_irq;
> >> >
> >> > -     /* Setup GPIOs. */
> >> > -     for (i = 0; i < pdata->nr_rows + pdata->nr_cols; i++) -
> >> >     pxa_gpio_mode(pdata->gpio_modes[i]); -
> >>
> >> That would require GPIO code to be replicated in every subarch piece.
> >> Do you expect many boards require special GPIO setup or maybe it would
> >> make sense to keep something similar to the code above (possibly have
> >> pointer to array of gpio modes and array size in pdata)? This way
> >> simpler boards will just supply the list and more complex setups can
> >> still do it themselves?
> >>
> >>
> > Actually, pin configurations on different platforms vary much, and to
> > keep the driver generic enough, this stuff should really be pushed to
> > the platform code.
> >
> > Currently, we (Nicolas, Russell King and I) are proposing a similar pin
> > configuration scheme as pxa3xx is currently doing for pxa{25x,27x}.
> >
> > The specific reasons behind this change are:
> >
> > 1. pxa3xx uses a different mechanism and API to configure pins other
> > than the pxa{25x,27x}'s pxa_gpio_mode(), i.e., pxa_gpio_mode() is no
> > longer valid for pxa3xx. So this is really processor specific code we
> > need to keep out side of the driver
>
> Why not use gpio_request/gpio_direction_input? Or they are broken for
> pxa3xx?
>

A big NO here, since keypad controller has dedicated pins whose functions
are _not_ GPIO. So it's not applicable here. Besides, PXA3xx has good
generic GPIO API support, FYI.

> >
> > 2. The driver should have no assumption to the platform configuration,
> > that is, when the ->probe() is called, any settings should be ready for
> > the driver to work, thus including pin configurations.
>
> Hmmm. gpio-keys behaves just in the opposite way: it sets all gpios it wants
> to use. And IMHO it's the correct way: the code isn't spread between several
> files, but instead is kept inside one (generic) file.
>

gpio-keys driver behaves differently since it _must_ know which GPIOs it's
going to control, otherwise the driver just fails. This is not the
case for keypad
controller, where it does not have to care about the pins once the pin
configuration is done.

> --
> With best wishes
> Dmitry
>
>
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-- 
Cheers
- eric