+tglx On 13/07/16 09:33, Bharat Kumar Gogada wrote: >> Subject: Re: PCIe MSI address is not written at pci_enable_msi_range call >> >> On 13/07/16 07:22, Bharat Kumar Gogada wrote: >>>> Subject: Re: PCIe MSI address is not written at pci_enable_msi_range >>>> call >>>> >>>> On 11/07/16 10:33, Bharat Kumar Gogada wrote: >>>>> Hi Marc, >>>>> >>>>> Thanks for the reply. >>>>> >>>>> From PCIe Spec: >>>>> MSI Enable Bit: >>>>> If 1 and the MSI-X Enable bit in the MSI-X Message Control register >>>>> (see Section 6.8.2.3) is 0, the function is permitted to use MSI to >>>>> request service and is prohibited from using its INTx# pin. >>>>> >>>>> From Endpoint perspective, MSI Enable = 1 indicates MSI can be used >>>> which means MSI address and data fields are available/programmed. >>>>> >>>>> In our SoC whenever MSI Enable goes from 0 --> 1 the hardware >>>>> latches >>>> onto MSI address and MSI data values. >>>>> >>>>> With current MSI implementation in kernel, our SoC is latching on to >>>>> incorrect address and data values, as address/data are updated much >>>>> later >>>> than MSI Enable bit. >>>> >>>> As a side question, how does setting the affinity work on this >>>> end-point if this involves changing the address programmed in the MSI >> registers? >>>> Do you expect the enabled bit to be toggled to around the write? >>>> >>> >>> Yes, >> >> Well, that's pretty annoying, as this will not work either. But maybe your MSI >> controller has a single doorbell? You haven't mentioned which HW that is... >> > The MSI address/data is located in config space, in our SoC for the logic behind PCIe > to become aware of new address/data MSI enable transition is used (0 to 1). > The logic cannot keep polling these registers in configuration space as it would consume power. > > So the logic uses the transition in MSI enable to latch on to address/data. A couple of additional questions: Does your HW support MSI masking? And if it does, does it resample the address/data on unmask? Thanks, M. -- Jazz is not dead. It just smells funny... -- 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
