.. _Check PIDX Update:

Check PIDX Update
=================

+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                              Name                             |          How to check?          |                Programmed by                |                              Maintained by                             |                                                                                                     Key information                                                                                                     |                       PIDX/CIDX                      |
+===============================================================+=================================+=============================================+========================================================================+=========================================================================================================================================================================================================================+======================================================+
|               Completion Queue Descriptor Status              | dma-ctl (dump queue completion) |              Completion Engine              |                            Completion Engine                           |                                                                                             Last location of Completion Ring                                                                                            | Contains PIDX/CIDX/Interrupt Status/Color status bit |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|             H2C Stream Writeback Status Descriptor            | dma-ctl (dump queue descriptor) |              Descriptor Engine              |                            Descriptor Engine                           |                                                                                                Last location of H2C Queue                                                                                               |                Containx PIDX and CIDX                |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|            MM C2H/H2C - Writeback Status Structure            | dma-ctl (dump queue descriptor) |              Descriptor Engine              |                            Descriptor Engine                           |                                                                                              Last Location of H2C/C2H Queue                                                                                             |                Containx PIDX and CIDX                |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
| Software maintains CIDX and copy of PIDX for completion queue |                                 |                                             |                                                                        |                                                                                                                                                                                                                         |                                                      |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|  Software maintains PIDX and copy of CIDX for H2C/C2H queues  |                                 |                                             |                                                                        |                                                                                                                                                                                                                         |                                                      |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|  Descriptor Engine also maintains CIDX and a copy of SW PIDX  |                                                                  dma-ctl (dump queue)                                                                  |                                                                                    Available in Hardware Context and Software Context                                                                                   |                                                      |
+---------------------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
| Descriptor Context                                                                                                                                                                                                     |                                                                                                Indexed by H2C and C2H QID                                                                                               |                                                      |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                        Hardware Context                       |       dma-ctl (dump queue)      |              Descriptor Engine              | Once the queue is enabled, context is dynamically updated by Hardware. |                                                                                                   Contains Status Only                                                                                                  |               Contains CIDX Information              |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+                                                                        +-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                         Credit Context                        |       dma-ctl (dump queue)      |              Descriptor Engine              |                                                                        |                                                                                                   Contains Status Only                                                                                                  |                                                      |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+                                                                        +-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                        Software Context                       |       dma-ctl (dump queue)      |                    Driver                   |                                                                        | Software context should only be updated through the direct mapped address space to update the PIDX and Interrupt Arm bit. See QDMA_DMAP_SEL_H2C_DSC_PIDX[2048] (0x18004) and QDMA_DMAP_SEL_C2H_DSC_PIDX[2048] (0x18008) |               Contains PIDX information              |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                       Completion Context                      |              dmactl             | Driver (PIDX is initialized to 0 by driver) |                            Completion Engine                           |                                                              Maintained on Per Queue basis. Stores the base address of the Completion Ring, PIDX, CIDX etc.                                                             |     Contains completion PIDX & CIDX information      |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                        Prefetch Context                       |       dma-ctl (dump queue)      |                    Driver                   |                                                                        |                                                                                                                                                                                                                         |                                                      |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                       Interrupt Context                       |       dma-ctl (dump queue)      |                    Driver                   |                                                                        |                                                                                                                                                                                                                         |                                                      |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                      Host Profile Context                     |       dma-ctl (dump queue)      |                    Driver                   |                                                                        |                                                                                                                                                                                                                         |                                                      |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                   Interrupt Aggregation Ring                  |             dma-ctl             |                                             |                                Hardware                                |                    If the interrupts for multipe queues are aggregated into the interrupt aggregatoin ring, the status descriptor information is available in the interrupt aggretatoin ring as well                    |                                                      |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+
|                           CMPT Entry                          | dma-ctl (dump queue completion) |              Completion Engine              |                            Completion Engine                           |                                                                                              Contains Color Bit informaton                                                                                              |                                                      |
+---------------------------------------------------------------+---------------------------------+---------------------------------------------+------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------+