On May 28, 2013, at 5:45 PM, Scott Wood wrote: > On 05/16/2013 01:29:45 AM, Kevin Hao wrote: >> All these boards use the same configuration file p1_p2_rdb_pc.h in >> u-boot. So they have the same pci bus address set by the u-boot. >> But in some of these boards the bus address set in dtb don't match >> the one used by u-boot. And this will trigger a kernel bug in 32bit >> kernel and cause the pci device malfunction. For example, on a >> p2020rdb-pc board the u-boot use the 0xa0000000 as both bus address >> and cpu address for one pci controller and then assign bus address >> such as 0xa00004000 to some pci device. But in the kernel, the dtb >> set the bus address to 0xe0000000 and the cpu address to 0xa0000000. >> The kernel assumes mistakenly the assigned bus address 0xa0004000 >> in pci device is correct and keep it unchanged. This will definitely >> cause the pci device malfunction. I have made two patches to fix >> this in the pci subsystem. >> http://patchwork.ozlabs.org/patch/243702/ >> http://patchwork.ozlabs.org/patch/243703/ >> But I still think it makes sense to set these bus address to match >> with the u-boot. This issue can't be reproduced on 36bit kernel. >> But I also tweak the 36bit dtb for the above reason. > > IIRC the reason for using 0xe0000000 on all PCIe roots is to maximize the > memory that is DMA-addressable without involving swiotlb. > > Maybe U-Boot should be fixed? > > -Scott
I feel that u-boot was the way it is to allow accessing each bus from the command line in u-boot w/o big changes for >32-bit addressing. Linux was able to handle the PCI bus addresses all being the same. - k _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
