On Mon, Nov 07, 2016 at 10:24:44AM +0100, Hans de Goede wrote: > > On Sun, Nov 06, 2016 at 06:54:11PM +0800, Icenowy Zheng wrote: > > > 06.11.2016, 18:13, "Hans de Goede" <[email protected]>: > > > > Hi, > > > > > > > > On 06-11-16 04:35, Chen-Yu Tsai wrote: > > > > > Hi everyone, > > > > > > > > > > I spent a bit of time adding DRM support for the A23 yesterday. > > > > > Icenowy successfully got DRM working for the A33 Q8 tablets. > > > > > > > > > > It occurred to me today that we have 2 types of panels for the > > > > > A33 Q8 tablets, one is 800x480 and the other is 1024x600. However > > > > > we are currently sharing the same dts file for both, and only > > > > > U-boot knows about the different resolutions. > > > > > > > > > > I see 2 ways to fix this. One would be to provide a separate > > > > > dts file for the 1024x600 variant. The other would be to get > > > > > U-boot to patch the dts file. > > > > > > > > > > Either way would require users upgrading U-boot, or at least > > > > > their boot scripts in the first case, though. > > > > > > > > > > Any ideas? > > > > > > > > Since we already have 2 u-boot configs for this having 2 dts files > > > > seems like the best solution to me. > > > > > > Maybe for compatibility we need 3 dts files... > > > > > > 1. Q8 dts : everything except display (For users migrated from the old > > > single-dt time) > > > 2. Q8 800x480 dts : #include <Q8 dts>, /panel/compatible = > > > "urt,umsh-8596md-t" > > > /* This compatible is what Chen-Yu used in sun5i-q8, and I used it also > > > on my A33 Q8 */ > > > 3. Q8 1024x600 dts : #include <Q8 dts>, /panel/compatible = foo > > > > I'm not sure why we need both actually. > > > > Even if the resolutions are the same, chances are the panel won't be, > > and will have different timings. > > So far all 800x480 and all 1024x600 q8 a23/a33 tablets work > with a single set of timings (per resolution).
That's a rather fragile assumption. And they probably have different tolerancies anyway, so you'll want different compatible anyway. > > I guess your plan is simply to use different compatible, > > There is no plan, since a single set of timing works for > all tablets encountered so far). Well, we still need to have a backup plan in case it's not the case anymore in the future. > > then we don't really need two different device > > trees in the first place, do we? > > It all depends on how closely we want to couple u-boot and the kernel. > > Either we need to have u-boot patch in the right panel compatible, but > only on q8_a33_tablet configs, or we stick with the one defconfig > 1 dts pattern used everywhere. > > Basically the problem is that currently both: > > configs/q8_a33_tablet_1024x600_defconfig > configs/q8_a33_tablet_800x480_defconfig > > Refer to the same dts, fixing that is really easy and > consistent with what we do in the other 100 sunxi defconfig-s > u-boot now has. Where as hot patching the panel compatible > requires q8_a33_tablet specific code in u-boot which I > would rather avoid. I definitely get that, but weren't you supposed to deal with that in your q8-manager? And you'll have to have q8 specific code somewhere anyway, so if it's not in U-Boot, it's going to be somewhere else, it's just moving the problem to someone else indefinitely. Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
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