On Thu, Aug 24, 2017 at 10:34:25AM +0530, Oza Pawandeep wrote: > PCIe spec r3.1, sec 2.3.2 > If CRS software visibility is not enabled, the RC must reissue the > config request as a new request. > > - If CRS software visibility is enabled, > - for a config read of Vendor ID, the RC must return 0x0001 data > - for all other config reads/writes, the RC must reissue the > request > > iproc PCIe Controller spec: > 4.7.3.3. Retry Status On Configuration Cycle > Endpoints are allowed to generate retry status on configuration > cycles. In this case, the RC needs to re-issue the request. The IP > does not handle this because the number of configuration cycles needed > will probably be less than the total number of non-posted operations > needed. > > When a retry status is received on the User RX interface for a > configuration request that was sent on the User TX interface, > it will be indicated with a completion with the CMPL_STATUS field set > to 2=CRS, and the user will have to find the address and data values > and send a new transaction on the User TX interface. > When the internal configuration space returns a retry status during a > configuration cycle (user_cscfg = 1) on the Command/Status interface, > the pcie_cscrs will assert with the pcie_csack signal to indicate the > CRS status. > When the CRS Software Visibility Enable register in the Root Control > register is enabled, the IP will return the data value to 0x0001 for > the Vendor ID value and 0xffff (all 1’s) for the rest of the data in > the request for reads of offset 0 that return with CRS status. This > is true for both the User RX Interface and for the Command/Status > interface. When CRS Software Visibility is enabled, the CMPL_STATUS > field of the completion on the User RX Interface will not be 2=CRS and > the pcie_cscrs signal will not assert on the Command/Status interface. > > Per PCIe r3.1, sec 2.3.2, config requests that receive completions > with Configuration Request Retry Status (CRS) should be reissued by > the hardware except reads of the Vendor ID when CRS Software > Visibility is enabled. > > This hardware never reissues configuration requests when it receives > CRS completions. > Note that, neither PCIe host bridge nor PCIe core re-issues the > request for any configuration offset. > > For config reads, this hardware returns CFG_RETRY_STATUS data when > it receives a CRS completion for a config read, regardless of the > address of the read or the CRS Software Visibility Enable bit. I can't remember how Stingray handles the CRS Software Visibility Enable bit. Is it a read-only zero? Is it writable? Does the hardware look at it all (I think not)? -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
