Messages in this thread | | | Subject | Re: [PATCH v2 RESEND] bus: mhi: core: Wait for ready state after reset | From | Hemant Kumar <> | Date | Wed, 10 Mar 2021 12:56:59 -0800 |
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On 3/10/21 12:41 PM, Jeffrey Hugo wrote: > After the device has signaled the end of reset by clearing the reset bit, > it will automatically reinit MHI and the internal device structures. Once > That is done, the device will signal it has entered the ready state. > > Signaling the ready state involves sending an interrupt (MSI) to the host > which might cause IOMMU faults if it occurs at the wrong time. > > If the controller is being powered down, and possibly removed, then the > reset flow would only wait for the end of reset. At which point, the host > and device would start a race. The host may complete its reset work, and > remove the interrupt handler, which would cause the interrupt to be > disabled in the IOMMU. If that occurs before the device signals the ready > state, then the IOMMU will fault since it blocked an interrupt. While > harmless, the fault would appear like a serious issue has occurred so let's > silence it by making sure the device hits the ready state before the host > completes its reset processing. > > Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: Hemant Kumar <hemantk@codeaurora.org>
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