From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnaud.patard@rtp-net.org (Arnaud Patard (Rtp)) Date: Wed, 20 Oct 2010 10:35:28 +0200 Subject: [patch 1/9] efikamx: read board id In-Reply-To: <20101020082418.GF28242@pengutronix.de> (Sascha Hauer's message of "Wed\, 20 Oct 2010 10\:24\:18 +0200") References: <20101019204253.162641893@rtp-net.org> <20101019205251.082848683@rtp-net.org> <20101019211507.GA28242@pengutronix.de> <20101020082418.GF28242@pengutronix.de> Message-ID: <87mxq9cldb.fsf@lechat.rtp-net.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Sascha Hauer writes: > On Tue, Oct 19, 2010 at 04:30:25PM -0500, Matt Sealey wrote: >> On Tue, Oct 19, 2010 at 4:15 PM, Sascha Hauer 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). > > Maybe it's possible to delay only the registering of the devices which > depend on the board revision, perhaps with a workqueue. But ok, I don't > care much and this won't be a show stopper for this patch. ok. Will wait a little bit more for comments and send a new patchset. Thanks, Arnaud