06-02-2020 10:54 AM
Is there anyway to disable the QDMA descriptor engine and use our own custom descriptors to interface with H2C and C2H engines in QDMA? Our descriptor fields have some custom settings (e.g. seq number, status) that are not present in any fields for QDMA descriptor bypass input ports. So we are looking for solutions to either add these fields into bypass ports or we can disable the descriptor engine all together and use our own descriptors and only use DMA engine to fetch data.
06-03-2020 04:34 AM
hello @LC256 ,
one refer the Example Design with Descriptor Bypass n/Out Loopback in pg302 ,The example design is generated when Descriptor Bypass for Read (H2C) and Descriptor ypass for Write (C2H) options are selected in the PCIe DMA tab. These options can be selectedwith any of the DMA Interface Options in the Basic tab. hen feeding the descriptor information on the bypass input interface, the user logic can request the QDMA Subsystem for PCIe to send a status write back to the host when it is done fetching the data from the host. The user logic can also request that a status be issued to it when the DMA is done. These behaviors can be controlled using the sdi and mrkr_req inputs in the ypass input interface. See QDMA Descriptor Bypass Input Ports for details in pg302.
let me know your input
06-03-2020 08:54 AM
Thank you. We looked at the example but we found that bypass input ports still lacked some configuration options we'd like. An example is an ability to insert in a sequence number in the descriptor. This makes it easier for our SW to track work in progress. We will look at the context programming CSRs and see if these can be used in the example design. Thanks for the suggestion and we will continue to dig into the design.