Andrew Morton schrieb: > On Tue, 19 Feb 2008 12:27:54 +0100 Clemens Koller <[EMAIL PROTECTED]> wrote: >> Benjamin Herrenschmidt schrieb: >>> On Tue, 2008-02-19 at 00:35 +0100, Clemens Koller wrote: >>>> [EMAIL PROTECTED] schrieb: >>>>> On Mon, 18 Feb 2008 08:18:47 +0100, Krzysztof Helt said: >>>>>> I know two fb drivers which use endianess information (pm2fb and >>>>>> s3c2410fb). >>>>>> Both resolve endianess at driver level. Actually, both handle it by >>>>>> setting special >>>>>> bits so the graphics chip itself reorder bytes to transform foreign >>>>>> endianess. >>>>>> I understand that this patch is for chips which cannot reorder bytes by >>>>>> themselves. >>>>> Does anybody know of such a chip that's actually available in the wild? >>>>> Or are >>>>> we writing drivers for speculative possible chips? >>>>> >>>> I had troubles with the Silicon Motion SM501/SM502 endianess on PowerPC >>>> PCI vs. LocalBus. >>>> The chip also has a register to swap endianess, but that seems to only >>>> affect some >>>> LocalBus modes. >>>> The current fb and X drivers are working, but when it comes to font >>>> aliasing and hw-acceleration, the problems start to rise again... >>> Most "sane" gfx chips nowadays provide configurable surfaces that allow >>> to perform the swap when writing/reading from regions of the >>> framebuffer, with the ability to set a different swapper setting (based >>> on bit depth) per region. >> Most! But not the SM50x. I still hope I would be wrong here. :-( >> >>> Then there is also the risk that your PCI<->Localbus has been wired >>> improperly :-) >> That's not an issue in my case. The SM50x can be connected to >> either an PCI or some Local/CPU-whateverbus IF. >> I.e. on the MPC85xx PowerPC, PCI and LocalBus are separate bussses. >> If the sm501 is attached to the MPC85xx' PCI like any other video card, >> the PCI config-space is can be accessed as usual, whereas the framebuffer >> memory area is byte-swapped compared to other common video cards. >> >> So, to get back on topic: >> I would welcome endianess swapping in SW. Some architectures (PowerPC) >> should also be able to do swapped-endian mmapping. I just haven't >> had time for a closer look but it looks also interesting way to do it >> that way. > > Bizarrely, the original author of the patch (Anton) has fallen off the cc. > Could whoever did that please thwap himself?
Propably my bad, being subscribed to several CCed lists... > Anyway, my head is now officially spinning. Did anyone actually have a > reason why we shouldn't proceed with Anton's patch? Since it seem that there are some odd chips out in the wild, I guess Valdis (also readded to CC:) has no more objections to give it a try. :-) Regards, Clemens _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
