From: amit.kucheria@linaro•org (Amit Kucheria)
To: linux-arm-kernel@lists•infradead.org
Subject: [patch 1/9] efikamx: read board id
Date: Wed, 20 Oct 2010 12:03:28 +0300 [thread overview]
Message-ID: <20101020090328.GH2562@matterhorn.lan> (raw)
In-Reply-To: <87zku9cmg0.fsf@lechat.rtp-net.org>
On 10 Oct 20, Arnaud Patard wrote:
> Amit Kucheria <amit.kucheria@linaro•org> writes:
>
> > On 10 Oct 19, Matt Sealey wrote:
> >> On Tue, Oct 19, 2010 at 4:15 PM, Sascha Hauer <s.hauer@pengutronix•de> wrote:
> >> > On Tue, Oct 19, 2010 at 10:42:54PM +0200, Arnaud Patard wrote:
> >> >> read board id value from the GPIO3_16/17/11
> >> >>
> >> >>
> >> >> +/* ? PCBID2 ?PCBID1 PCBID0 ?STATE
> >> >> + ? ? 1 ? ? ? 1 ? ? ?1 ? ?ER1:rev1.1
> >> >> + ? ? 1 ? ? ? 1 ? ? ?0 ? ?ER2:rev1.2
> >> >> + ? ? 1 ? ? ? 0 ? ? ?1 ? ?ER3:rev1.3
> >> >> + ? ? 1 ? ? ? 0 ? ? ?0 ? ?ER4:rev1.4
> >> >> +*/
> >> >> +static void __init mx51_efikamx_board_id(void)
> >> >> +{
> >> >> + ? ? int id;
> >> >> +
> >> >> + ? ? /* things are taking time to settle */
> >> >> + ? ? msleep(500);
> >> >
> >> > Is it really necessary to delay the boot process such a long time?
> >>
> >> Yes. On older boards the PCBID pins are pulled high by IOMUX settings
> >> (a pulldown on the board on newer revisions will keep it down). IOMUX
> >> and GPIO stuff takes a little while to settle in, so if you do it
> >> immediately, it will return some freakish values based on random GPIO
> >> setup (it may be high, low, or none of the above at any point before
> >> the pad setting kicks in).
> >
> > Then perhaps do this only for the older boards?
>
> How can you detect older boards without looking at board id pins ? :)
You don't. I was suggesting a config option that doesn't penalise those with
non-buggy boards....
> >
> > So by default there is no delay, but when a (new) config option is enabled,
> > delay boot.
>
> I don't think it's a good idea. This would mean that the same kernel
> can't run on old and new boards. Also, there's no way to easily know
> which board you have (I don't consider opening the box is an easy way)
> so it's likely that someone will get this wrong sooner or later.
...but you're right. If one has to support a variety of boards on single
kernel, this won't work.
/Amit
next prev parent reply other threads:[~2010-10-20 9:03 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-19 20:42 [patch 0/9] efikamx support improvements Arnaud Patard (Rtp)
2010-10-19 20:42 ` [patch 1/9] efikamx: read board id Arnaud Patard (Rtp)
2010-10-19 21:15 ` Sascha Hauer
2010-10-19 21:30 ` Matt Sealey
2010-10-20 7:54 ` Amit Kucheria
2010-10-20 8:12 ` Arnaud Patard (Rtp)
2010-10-20 9:03 ` Amit Kucheria [this message]
2010-10-20 8:24 ` Sascha Hauer
2010-10-20 8:35 ` Arnaud Patard (Rtp)
2010-10-20 8:59 ` Matt Sealey
2010-10-20 9:16 ` Uwe Kleine-König
2010-10-20 17:26 ` Matt Sealey
2010-10-20 19:26 ` Loïc Minier
2010-10-20 19:53 ` Arnaud Patard (Rtp)
2010-10-21 1:32 ` Matt Sealey
2010-10-20 20:53 ` Matt Sealey
2010-10-19 20:42 ` [patch 2/9] efikamx: add mmc support Arnaud Patard (Rtp)
2010-10-19 20:42 ` [patch 3/9] imx51: enhance/fix iomux configuration Arnaud Patard (Rtp)
2010-10-19 21:04 ` Sascha Hauer
2010-10-20 8:14 ` Arnaud Patard (Rtp)
2010-10-20 9:14 ` Eric Bénard
2010-10-20 9:26 ` Arnaud Patard (Rtp)
2010-10-20 9:18 ` Eric Bénard
2010-10-20 9:29 ` Arnaud Patard (Rtp)
2010-10-20 9:41 ` Amit Kucheria
2010-10-20 10:00 ` Uwe Kleine-König
2010-10-20 10:12 ` Arnaud Patard (Rtp)
2010-10-20 12:10 ` Uwe Kleine-König
2010-10-19 20:42 ` [patch 4/9] imx51: add gpio mode for csi1 {h,v}sync Arnaud Patard (Rtp)
2010-10-19 20:42 ` [patch 5/9] efikamx: add leds support Arnaud Patard (Rtp)
2010-10-20 11:15 ` Amit Kucheria
2010-10-19 20:42 ` [patch 6/9] efikamx: add support for power key Arnaud Patard (Rtp)
2010-10-19 20:43 ` [patch 7/9] imx51: fix gpio_4_24 and gpio_4_25 pad configuration Arnaud Patard (Rtp)
2010-10-19 20:43 ` [patch 8/9] efikamx: add spi nor support Arnaud Patard (Rtp)
2010-10-20 11:26 ` Amit Kucheria
2010-10-20 12:01 ` Arnaud Patard (Rtp)
2010-10-20 12:32 ` Amit Kucheria
2010-10-20 17:36 ` Matt Sealey
2010-10-20 17:55 ` Arnaud Patard (Rtp)
2010-10-20 20:51 ` Matt Sealey
2010-10-19 20:43 ` [patch 9/9] efikamx: add reset Arnaud Patard (Rtp)
2010-10-19 23:51 ` Fabio Estevam
2010-10-20 8:13 ` Arnaud Patard (Rtp)
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