Re: PCIe MSI address is not written at pci_enable_msi_range call

From: Marc Zyngier
Date: Mon Jul 11 2016 - 06:21:55 EST

[Please don't top-post]

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 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.

Interesting. It looks like we're doing something wrong in the MSI flow.
Can you confirm that this is limited to MSI and doesn't affect MSI-X?


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