net: macb: queue tie-off or disable during WOL suspend

When GEM is used as a wake device, it is not mandatory for the RX DMA
to be active. The RX engine in IP only needs to receive and identify
a wake packet through an interrupt. The wake packet is of no further
significance; hence, it is not required to be copied into memory.
By disabling RX DMA during suspend, we can avoid unnecessary DMA
processing of any incoming traffic.

During suspend, perform either of the below operations:

- tie-off/dummy descriptor: Disable unused queues by connecting
  them to a looped descriptor chain without free slots.

- queue disable: The newer IP version allows disabling individual queues.

Co-developed-by: Harini Katakam <harini.katakam@amd.com>
Signed-off-by: Harini Katakam <harini.katakam@amd.com>
Signed-off-by: Vineeth Karumanchi <vineeth.karumanchi@amd.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Tested-by: Claudiu Beznea <claudiu.beznea@tuxon.dev> # on SAMA7G5
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

0 files changed, 0 insertions, 0 deletions