Re: [PATCH net] net: bcmgenet: keep RBUF EEE/PM disabled

[Florian Fainelli <florian.fainelli@broadcom.com>]

On 5/20/26 11:43, Nicolai Buchwitz wrote:
> Setting RBUF_EEE_EN | RBUF_PM_EN in RBUF_ENERGY_CTRL breaks the RX
> path on GENET hardware once MAC EEE becomes active. RX traffic stops
> flowing while the link stays up and the usual descriptor/RX error
> counters remain quiet. In that state the MAC still accepts frames
> (rbuf_ovflow_cnt keeps climbing) but RBUF no longer forwards them to
> DMA, so rx_packets is no longer incremented at the netdev level. On
> some boards the corruption ends up as a paging fault in
> skb_release_data via bcmgenet_rx_poll on an LPI exit.
> 
> Reproduced on Pi 4B (BCM2711 + BCM54213PE) and confirmed by Florian
> Fainelli on an internal Broadcom 4908-family board with the same crash
> signature. RBUF_PM_EN is not publicly documented.
> 
> This shows up more often now that phy_support_eee() enables EEE by
> default, but it also affects older kernels as soon as TX LPI is
> turned on via ethtool, so it is not specific to recent changes.
> 
> Always clear RBUF_EEE_EN | RBUF_PM_EN in bcmgenet_eee_enable_set so
> the bits stay off across resets. UMAC and TBUF setup is left alone so
> TX-side EEE keeps working.
> 
> Link: https://github.com/raspberrypi/linux/issues/7304
> Fixes: 6ef398ea60d9 ("net: bcmgenet: add EEE support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>

Thank you Nicolai!
-- 
Florian