net: bcmgenet: mask DMA_TIMEOUT_MASK when reading DMA_RING0_TIMEOUT

bcmgenet_get_coalesce() reads DMA_RING0_TIMEOUT to calculate
rx_coalesce_usecs without masking out bits outside DMA_TIMEOUT_MASK
(16 bits). If upper bits are non-zero or contain status/flags, the
computed value of rx_coalesce_usecs returned to userspace via ethtool
becomes corrupted.

Mask the register read with DMA_TIMEOUT_MASK before computing the
timeout in microseconds.

Fixes: 4a29645bfe ("net: bcmgenet: Implement RX coalescing control knobs")
Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/20260921220021.281418-6-florian.fainelli@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Florian Fainelli 2026-09-21 15:00:21 -07:00 • committed by Jakub Kicinski
commit d64e277b95