linux-kernel - Re: [PATCH 0/4] Start getting rid of pdata callbacks with gpio_find_by_chip

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Date:	Fri, 2 Mar 2012 09:30:18 -0800
From:	Tony Lindgren <tony@...mide.com>
To:	Rajendra Nayak <rnayak@...com>
Cc:	linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
	linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/4] Start getting rid of pdata callbacks with
 gpio_find_by_chip_name()

* Rajendra Nayak <rnayak@...com> [120302 00:35]:
> Hi Tony,
> 
> On Friday 02 March 2012 12:25 AM, Tony Lindgren wrote:
> >Hi all,
> >
> >This series adds gpio_find_by_name() that allows finding
> >GPIOs on specific gpio_chips. As the GPIO numbers can be
> >dynamic, it's hard to find the GPIO numbers from drivers
> >using them directly.
> >
> >So far we've dealt with this using platform specific callbacks,
> >but that is messy. This series removes the needs for these
> >callbacks for omap hsmmc driver. Further callbacks can be
> >removed people are OK with adding gpio_find_by_name().
> >
> >This series is based on the omap fixes-non-critical that's
> >needed for the arch/arm/mach-omap2 parts of this series.
> 
> I tested these on my beagle/panda/omap4sdp and they seem to
> work fine, also fixing the broken panda card detect (due to
> missing card_detect_irq in the board file). There are still
> issues however when I build twl4030-gpio as a module, which I
> already commented on, and the fact that the init sequence now
> works by luck :)

Hmm it should not be luck based, loading omap_hsmmc module
should fail with a sensible error if the configured card detect
or write protect is not available.

I guess this is with twl6030 non-gpio based card detect?

If so, I'll add something to pass the twl6030 card detect from
pdata so we can fail with a sensible error in that case too.

Also, sounds like twl as module and mmc built in case won't
work without deferred probe. But at least there is a sensible
error for that. And maybe we can prevent that in Kconfig.

> The other issue also is that the multiple insmod/rmmod test
> suggested by Russell still fails, since the second time around
> the gpio_requests in the board callback fail because they are
> not freed when you do a module unload/unbind.
> That would need this patch from me to add the .teardown
> hooks
> http://marc.info/?l=linux-omap&m=133007767831297&w=2

Yes let's add the teardown patch as a fix for now, but let's
plan on getting rid of the twl_setup callback function
completely.

With these patches LCD and WLAN too can request the twl gpios
directly from the driver based on gpio_chip + gpio offset.

Regards,

Tony
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