On Sun, Feb 05, 2012 at 04:04:07PM -0500, Robert P. J. Day wrote: > On Sun, 5 Feb 2012, Eric Bénard wrote: > > > Le Sun, 5 Feb 2012 13:00:13 -0500 (EST), > > "Robert P. J. Day" <rpjday@xxxxxxxxxxxxxx> a écrit : > > > > > On Sun, 5 Feb 2012, Eric Bénard wrote: > > > > > > > This is the case where u-boot is built with SPL thus reoplacing > > > > x-load : they always read NAND ID as some XM boards were mounted > > > > with Numonyx POP which includes NAND and 166MHz RAM when mot XM > > > > boards have a POP with only 200MHz DDR (and in that case > > > > manufacturer ID is 0). So even on a XM you need to check the NAND ID > > > > to set the right RAM settings. > > > > > > ah, got it. but what about in a more general case? what if you > > > have a current, accurate definition for an existing board? then a > > > *slight* variant of that board comes along, for which some settings in > > > the defconfig file are simply wrong? > > > > > > are there any examples of that in barebox right now? and if not, > > > how would one handle them? put another way, what if *all* xM boards > > > had no NAND? then we'd be back to my original question, and it's > > > still not clear how you'd define that new board for barebox. > > > > > if no XM board had NAND, you would simply check the board type using the > > GPIO sampled and you wouldn't register the nand (line 305 in > > board-beagle.c) and the fact that the nand driver is enabled is not a > > problem if the device is not registrered the driver won't be used. > > not to put too fine a point on it but ... yuck. don't get me wrong, > i certainly see the value in testing things like board versions so the > code knows how to handle small differences between similar boards > (memory speed, flash types or sizes and so on). > > but this isn't a small difference -- this represents potentially an > entire subsystem (NAND) that i want the ability to de-activate. in a > perfect world, i want the ability to say concisely that i have a > beagle but i have no NAND flash, period. i don't want any of the NAND > code compiled, i don't want it included in the binary, so obviously i > don't want any of that code to run, only to realize it has nothing to > do. The mentioned U-Boot code does not use any of the nand layer but only some omap specific function to detect the nand id (identify_nand_chip). This means that you can add this code to barebox and still disable nand support. If you still want to have a more fine grained config we can add a config MACH_PANDA_XM_VARIANT bool config MACH_PANDA_XM_DETECT_RAM_TYPE bool But we should add such options with care. Generally I don't really like to ask the user complicated questions for things that can be autodetected. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
