[patch 1/9] efikamx: read board id

[Sascha Hauer]

On Tue, Oct 19, 2010 at 04:30:25PM -0500, Matt Sealey wrote:
> On Tue, Oct 19, 2010 at 4:15 PM, Sascha Hauer <s.hauer at 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).

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.


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