On Tue, Jun 02, 2015 at 10:29:09AM +0200, Hans de Goede wrote: > Hi, > > On 02-06-15 10:14, Maxime Ripard wrote: > >On Sat, May 30, 2015 at 04:55:06PM +0200, Hans de Goede wrote: > >>The Ippo-q8h is a tablet circuit board commonly found in cheap Android > >>tablets. The v1.2 version can be used with either an A23 or A33 SoC. > >> > >>This adds a dts file for the v1.2 board with an A33 SoC and a 1024x600 > >>LCD screen (most of these tablets have a 800x480 screen). > > > >I think the difference between the resolution here is more of a case > >for the DT quirks interface: > >https://lkml.org/lkml/2015/2/18/258 > > I would expect the only difference between the 2 dts files to be the > node describing the lcd panel, so yes that makes somewhat sense. > > >Do you know if there's some way to autodetect the two board versions > >(like a board id somewhere in an EEPROM)? > > No, AFAIK there is no way to tell the difference. There is no eeprom no > the board, and we really cannot rely on the nand contents. Ok. > >If not, then maybe u-boot can simply add that board compatible to the > >list, and we'll base our logic on that when we'll need it. > > That means extra logic in u-boot, and on the kernel side, for what > benefit exactly? Such logic would make sense if there was one u-boot > image which runtime adjusted itself, but that is not an option. For what benefit? One kernel image which runtime adjusts itself. It's especially possible if u-boot's image is not, which seems to be what you're saying. > And we can avoid copy and paste on the dts side by putting all > the common stuff in a common file and including that, I believe > that that is better (KISS = better) since we've no way to runtime > do the right thing AFAICT. My concern is about the ever-growing number of DTS that just are small variations of one or the other. What about the time when we'll discover that this board has a variant that has an emmc, and some that don't have any button, or the i2c bus 2 not wired, and one other that doesn't have any HDMI? Do we really want to have a dts called sun8i-a33-q8h-emmc-lcd800x600-nohdmi-noi2c2-nobuttons.dts? Especially when we will have the one that we include here that will not have followed this convention because it was introduced before that, and that we have a way to deal with this nicely? You chose to consider the DTS names an ABI, the best way to handle this is to have a DTS as generic as possible, and leave all these small variations outside of the name. Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com
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