intx_msi_request causes the
generation of an MSI interrupt if MSI is enabled.
intx_msi_request is asserted, it
should be de-asserted immediately in the next clock cycle. The
intx_msi_grant assertion indicates the requested interrupt has been sent
on the PCIe block. The vector number being used in
the interrupt packet will be determined based on the value provided at the
msi_vector_num[4:0] signal. You must implement a mechanism in the
user application to know when the interrupt routine has been serviced. This detection
can be done in many different ways depending on your application and your use of this
interrupt pin. This typically involves a register (or array of registers) implemented in
the user application that is cleared, read, or modified by the host software when an
Interrupt is serviced.
The intx_msi_request signal is positive-edge detected and synchronous to
axi_aclk. intx_msi_request must be de-asserted for at least one
axi_aclk cycle before re-asserting it to send another MSI interrupt on the same vector
or on a different vector.
The MSI vector number being used must not exceed the number of MSI
vectors being enabled by the host. This information can be queried from
msi_vector_width[2:0] signal after the host enumerated and enabled
MSI interrupt at runtime. The encoding of
is shown in the following table.
|Value||Number of Messages Requested||Output Signal, MSI_Vector_Width (2:0)|