Hello, On 07/22/2010 04:47 AM, Jassi Brar wrote: > After implementing driver for PCIe RC controller of a SOC, I came > across peculiarity > while testing SIL3132 directly connected to the root port. > > My RC IP is configured for maximum of 256bytes of payload size. > The sata_sil24 driver unconditionally sets pcie_set_readrq(pdev, 4096) > for the endpoint > which apparently works for 'every' other host irrespective of their capacity. > > In my case it works only if I change to > pcie_set_readrq(pdev, 256) > > Shouldn't the Linux PCI have provision to allow max_read/payload_size > not higher than > the least of max capacities of all agents in the chain ? > > I see similar use of pcie_set_readrq(pdev, 4096), so could be I am > missing something ? It's been a while since I read pci-e spec but IIUC readrq size and payload size are independent and if readrq is larger than payload size it's supposed to complete in multiple steps. I could be wrong tho. Thanks. -- tejun -- 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
