Hi Andrew, On Tue, May 26, 2015 at 8:17 PM, Andrew Bradford <and...@bradfordembedded.com> wrote: > Hi Bin, > > On 05/23 23:50, Bin Meng wrote: >> +Simon. >> >> Hi Andrew, >> >> On Sat, May 23, 2015 at 3:09 AM, <and...@bradfordembedded.com> wrote: >> > From: Andrew Bradford <andrew.bradf...@kodakalaris.com> >> > >> > PCI on Intel Baytrail is mapped to 0x80000000, which is not always at >> > the end of SDRAM, such as when running with 4 GiB of SDRAM. The PCI bus >> > memory mapping must stay within low memory and so when running with > >> > 2 GiB of SDRAM, there is a hole in the SDRAM between 2 GiB and 4 GiB for >> > memory mapped IO, such as PCI. >> >> Are you saying that if we mount 4GB DDR DIMM on the MinnowMax board, >> the Intel FSP will only put 0~2G as system RAM space, and leave 2G~4G >> as PCI address and other I/Os? > > Yes. If you mount 4 GiB of SDRAM onto an E3800 processor, then physical > addresses from 0 to just below 2 GiB will be SDRAM (as per the HOBs) and > also from 4 GiB to 6 GiB (also verified via the HOBs). The space from 2 > GiB to 4 GiB will be mapped as various other regions.
Ah, that's exactly the information I want :) > If you see section 4.1.1.1 (page 71 in the January 2015, Revision 3.6) > E3800 datasheet, it shows that from 2 GiB to 4 GiB is mapped for PCI, > Abort Page, Local APIC, and the Boot Vector. There's a lot of space in > this area which appears unused, so I'm unsure as to why the area is so > large. > > I have an Intel Valley Island board with E3825 and a 4 GiB SODIMM. I'm > working on getting patches ready for this board but found that if I > enabled all 4 GiB of SDRAM that the PCI bus would not function > correctly. With this patch then the PCI bus functions (I'm able to do > network operations with the RTL8111 Ethernet adapter). > >> I see from minnowmax.h, the PCI address starts from 0xd0000000. >> >> #define CONFIG_PCI_MEM_BUS 0xd0000000 >> #define CONFIG_PCI_MEM_PHYS CONFIG_PCI_MEM_BUS >> #define CONFIG_PCI_MEM_SIZE 0x10000000 >> >> #define CONFIG_PCI_PREF_BUS 0xc0000000 >> #define CONFIG_PCI_PREF_PHYS CONFIG_PCI_PREF_BUS >> #define CONFIG_PCI_PREF_SIZE 0x10000000 > > I see that hose->regions+0 is set to CONFIG_PCI_MEM_BUS and > hose->regions+2 is set to CONFIG_PCI_PREF_BUS. However I'm modifying > hose->regions+3. So the values from minnowmax.h *are* being used. I'm > not yet that familiar with PCI configuration, so likely I'm not fully > understanding how u-boot sets this up. > The regions+3 is used by the inbound access, eg: PCI device access to system memory. > Possibly my address of 0x80000000 is not correct, even though it works > for me. But 0x80000000 is where it was being placed before, since it > was going at the end of SDRAM (2GiB on minnowmax). > You understanding is correct. We should only open 2GiB inbound memory window for PCI devices. > If I artificially limit the amount of SDRAM by setting the fsp > configuration to memory-down and then setting the DRAM configuration > values such that I mimmic 1 GiB or 2 GiB of SDRAM, having my patch still > provides access to the PCI bus, so with my patch there should be no > adverse affects on E3800 systems that have less than 4 GiB of SDRAM. > But without my patch, when running with >=4 GiB of SDRAM, PCI accesses > end up returning "pci_hose_bus_to_phys: invalid physical address" > errors. > Yes, this all makes sense, so Reviewed-by: Bin Meng <bmeng...@gmail.com> Regards, Bin _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
