On Thu, Oct 16, 2014 at 10:48:34AM +0200, Hans de Goede wrote: > Hi, > > On 10/15/2014 12:34 PM, Siarhei Siamashka wrote: > > On Wed, 15 Oct 2014 12:12:11 +0200 > > Hans de Goede <hdego...@redhat.com> wrote: > > > >> This change breaks various hardcoded assumptions in the linux-sunxi-3.4 > >> kernels, causing a divide by 0 error in the linux-sunxi-3.4 nand driver, > >> rendering 3.4 kernels unbootable. Besides this problem, it also breaks LCD > >> output (on devices without nand). > >> > >> Fixes for these issues are being added to the linux-sunxi-3.4 kernel, but > >> for > >> now it seems better to revert this. > >> > >> This reverts commit 013f2d746955147439215a4939655c9ed6bdd866. > > > > As mentioned in the commit message > > https://www.mail-archive.com/linux-sunxi@googlegroups.com/msg07884.html > > the hardcoded assumptions in the sunxi-3.4 kernel are still bad > > with or without this revert if somebody tries to use higher DRAM > > clock speeds. > > > > The patch in question just smokes out bugs, which are otherwise still > > there. > > > > Going forward, the mainline kernel needs the G2D driver and it needs > > to run at a decent clock speed to be provide reasonable performance. > > Low PLL5P clock speed is limiting our options. > > > > This revert does not do anyone any favour and only postpones the > > resolution of the problem. > > I agree that we need to fix the linux-sunxi-3.4 kernels to work properly with > different pll5 settings, which is why I've actually send a fix for some pll5 > issues to the linux-sunxi list and acked your patches which fix other bits. > > I can understand you want to have optimal settings for the G2D stuff, and I'm > not against that. But getting the G2D stuff upstream is something which > is still far in the future. I really want people to be able to start using > upstream u-boot, starting today. And it will take some time for the sunxi-3.4 > fixes to trickle down to users.
We should be doing things right, in mainline. To bring up a different example, on TI OMAP4 parts at least for a long time in order to use mainline U-Boot on older kernels you had to manually add CONFIG_SOMETHING_OR_ANOTHER to enable additional clocks/mux that the old kernels had incorrectly relied on U-Boot to set. If we must do strange things to support old and incorrect but in the wild kernels we need to (a) make it opt-in (easier now with Kconfig!) and (b) schedule a removal of the hack all the same. -- Tom
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