CVS commit: src/sys/dev/pci

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sat Aug  6 15:38:42 UTC 2022

Modified Files:
        src/sys/dev/pci: if_sip.c

Log Message:
sip(4): Tidy up DMA syncs.

- No membar_producer in sip_init_rxdesc -- use bus_dmamap_sync with
  BUS_DMASYNC_PREWRITE to order updates to the DMA descriptors.

- Omit needless membar_producer in sip_init_txdesc -- the hardware
  will not look at any of these descriptors until we set CMDSTS_OWN
  on the first one in the sequence, which is done later in the
  caller, sipcom_start.

- In gsip_rxintr, make sure to read cmdsts _before_ extsts, by
  separating them with BUS_DMASYNC_PREREAD.  Otherwise, the CPU might
  reorder the loads and read a stale extsts first before witnessing
  an updated cmdsts with the CMDSTS_OWN bit that transfers ownership
  of the rx packet to us.


To generate a diff of this commit:
cvs rdiff -u -r1.186 -r1.187 src/sys/dev/pci/if_sip.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.