On 11/23/2015 08:24 AM, Scott Wood wrote: > On Sat, 2015-11-21 at 15:29 -0800, York Sun wrote: >> >> On 11/21/2015 02:55 PM, York Sun wrote: >>> Roy, >>> >>> Do you remember the reason why we use different virtual memory address >>> from pci >>> bus address with 36-bit? For example >>> >>> include/configs/P1022DS.h-496-#define CONFIG_SYS_PCIE1_MEM_VIRT 0xc0000000 >>> include/configs/P1022DS.h-497-#ifdef CONFIG_PHYS_64BIT >>> include/configs/P1022DS.h:498:#define CONFIG_SYS_PCIE1_MEM_BUS 0xe0000000 >>> include/configs/P1022DS.h-499-#define CONFIG_SYS_PCIE1_MEM_PHYS >>> 0xc40000000ull >>> include/configs/P1022DS.h-500-#else >>> include/configs/P1022DS.h:501:#define CONFIG_SYS_PCIE1_MEM_BUS 0xc0000000 >>> include/configs/P1022DS.h-502-#define CONFIG_SYS_PCIE1_MEM_PHYS 0xc0000000 >>> include/configs/P1022DS.h-503-#endif >>> >>> As far as I can tell, the following is the mapping >>> >>> TLB: MEM_VIRT=>MEM_PHYS >>> PCI: MEM_BUS=>MEM_PHYS >>> LAW: MEM_PHYS=>pcie interface >>> >>> Being different for MEM_VIRT and MEM_BUS cause confusion. When I run "pci >>> header" command to show the BARs, I expect I can use "md" to access the >>> BAR >>> address. That's not the case if MEM_BUS is different from MEM_VIRT. >>> >>> I forget why we did this for 36-bit addressing. The MEM_VIRT is the same >>> as >>> MEM_BUS for 32-bit addressing. And why do we use the same MEM_BUS address >>> for >>> all PCIe hose? I know they are not conflicting, but is it necessary? >> >> (I hope Becky and Kumar still follow this mailing list) >> >> I dug out an old commit 4c78d4a6c01621721b732418e1c6da684a56bbb1 by Becky >> Bruce. >> She believed overlapping the bus address for PCI controllers leaves more >> space. >> That's true. But we haven't use more than 512MB in u-boot. If we do need >> more >> space, we can easily move things around if we have PHYS_64BIT. If no >> objection, >> I'd like to change this back. > > I object. It's not about how much RAM is used in U-Boot; it's about how much > memory the OS needs to bounce-buffer for DMA. The addresses set up by U-Boot > should match what's in the device tree. Yes, on 85xx Linux reprograms the > ATMU based on the device tree rather than trusting U-Boot, but that doesn't > mean every OS does.
Isn't this backward? I mean the device tree should match u-boot, or u-boot should fix up the device tree, right? I checked several device tree files in kernel. We are not using more than 512MB for each PCI. What's the benefit of using the same address 0xe0000000? York _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
