Hi all,
I am bringing up XHCI support for our SOC and have run into several issues with U-Boot's XHCI code.
1. I need to use a wrapper I call xhci_readl/xhci_writel since all of our I/O is to 64-bit addresses rather than readl/writel which work for PCIe. While xhci_readl/xhci_writel is used in most places there are a few places this is missing.
2. A memory address used by a pointer is not a DMA address on MIPS. On MIPS a wrapper is needed for all read/write operations to descriptors to map the addresses. Generally U-Boot runs in KSEG0 where a pointer always has bit 31 set. In our case we run it in virtual memory with U-Boot loaded at the top of memory (which might be as high as 64GB+256MB).
3. xhci_alloc_virt_device is missing a conversion from big endian to little endian on line 401 of xhci-mem.c.
4. I keep getting hit with
BUG_ON(GET_COMP_CODE(le32_to_cpu(event->trans_event.transfer_len != COMP_STOP))); on line 491 in xhci-ring.c. Commenting this out seems to work fine.
5. I also hit the BUG_ON on line 722 of xhci-ring.c since on MIPS a pointer is not a DMA address and the fact that we use 64-bit addresses where pointers are 32-bits.
I ran into similar issues with EHCI where again we have to map pointers to physical addresses and use our own wrappers for register accesses.
At some point I would love to merge our stuff back into the mainline U-Boot but it's going to be a huge job given that we probably have almost 250K lines of code involved for our MIPS SOCs.
-Aaron