On 10/28/2016 09:58 AM, Ray Jui wrote: > Hi Rafal, > > On 10/28/2016 8:31 AM, Rafał Miłecki wrote: >> On 20 April 2016 at 20:18, Ray Jui <ray.jui@xxxxxxxxxxxx> wrote: >>> Hi Rafal/Florian/Arnd, >>> >>> After a couple days of email exchange with the ASIC team, I think I've >>> figured out the behavior on all of the Broadcom SoCs that use this iProc >>> PCIe controller. >>> >>> On NSP, Cygnus, and NS2: >>> - There's an APB error enable register at offset 0xf40 from the iProc PCIe >>> controller's base address. If one clears bit 0 (enabled by default after >>> chip POR) of that register, one can stop this from being forwarded to "iProc >>> host" as an APB error/external imprecise abort >>> - I will submit a patch to the iProc PCIe driver to disable this error >>> forwarding >>> >>> On NS: >>> - Unfortunately, there's no such control register in NS. In other words, we >>> cannot disable this error at the PCIe controller level >>> - FSR code corresponds to external (bit[12] = '1'), read (bit[11] = '0'), >>> imprecise abort (bits[10][3:0] = '1''0110'), i.e., external imprecise abort >>> triggered by read access. Our ASIC team believes a read access to a >>> non-exist APB register can also trigger an abort with the same FSR code. >>> Note this is the tricky part, by registering an abort hook that skips this >>> particular FSR, one has a chance of skipping other aborts triggered by >>> accessing invalid APB registers. But given that this cannot be disabled for >>> the PCIe controller NS, I'm not sure what approach we should take. Any >>> thoughts? >> >> It's really late reply but I wanted to finally handle this problem. >> >> From Ray's e-mail it seems Northstar is the only platform requiring >> this workaround. So we don't have to worry about arm64. > > Yes, Northstar is the only platform that requires this workaround. Even > the arm32 platforms like NSP and Cygnus can disable unsupported request > being forwarded as APB error. I've recently sent out a patch series to > fix this for all other platforms, and sorry I should have included you > in the email but I did not. I'll include you when revision 2 is sent out. > >> >> We have two options then: >> 1) Add workaround in arch/arm/mach-bcm/bcm_5301x.c >> 2) Add workaround into built-in drivers/pci/host/pcie-iproc-fault.c > > How do you plan to implement pcie-iproc-fault.c? If it's similar to what > you have now, then I think it fits more to bcm_5301x.c I was going to suggest adding it to the PCIe driver so as to make it localized there, but that seems like a better idea, in case the PCIe driver is not built into the kernel, or as a module, it seems like a nice thing to be able to clear the abort. -- Florian -- 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
