Eran Liberty wrote: > This should probably go to the Freescale support, as it feels like a > hardware issue yet the end result is a very frozen Linux kernel so I > post here first... > > I have a programmable FPGA PCIe device connected to a Freescale's P2020 > PCIe port. As part of the bring-up tests, we are testing two faulty > scenarios: > 1. The FPGA totally ignores the PCIe transaction. > 2. The FPGA return a transaction abort. > > Both are plausible PCIe behavior and their should be outcome is > documented in the PCIe spec. The first should be terminated by the > transaction requestor timeout mechanism and raise an error, the second > should abort the transaction and raise and error. > > In P2020 if I do any of those the CPU is left hung over the transaction. > > something like: > in_le32(addr) > > is turned into: > 7c 00 04 ac sync 7c 00 4c 2c lwbrx r0,0,r9 > 0c 00 00 00 twi 0,r0,0 > 4c 00 01 2c isync > > assembly code, where in r9 (in this example) hold an address which is > physically mapped into the PCIe resource space. > > The CPU will hang over the load instruction. > > Just for the fun of it, I have wrote my own assembly function omitting > everything but the load instruction; still freeze. > Replace "lwbrx" with a simple "lwz"; still freeze. > > It looks like the CPU snoozes till the PCIe transaction is done with no > timeouts, ignoring any abort signal. > AFAIK we can set one bit on PEX_ERR_DISR to detect PCI Express completion time-out. If so one interrupt should be issued. But I'm not sure if this can fix your issue. Tiejun > I am going to: > A. Try to reach the Freescale support. > B. Asked the FPGA designed to give me a new behavior that will stall the > PCIe transaction replay for 10 sec, but after those return ok. > C. report back here with either A or B. > > If you have any ideas I would love to hear them. > > -- Liberty > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@xxxxxxxxxxxxxxxx > https://lists.ozlabs.org/listinfo/linuxppc-dev > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
