Re: [cip-dev] [PATCH 6.1.y-cip 0/3] net: stmmac: Fix EEE-related issues

[Pavel Machek <pavel@nabladev.com>]

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Hi!

> 
> When testing Ethernet on the Renesas RZ/V2H and RZ/V2N platforms with
> 6.1-cip, LPI interrupt storms and VLAN register access timeouts were
> observed.
> 
> Both issues are caused by the RX clock stop feature being enabled by
> default. When EEE is active and the link is idle, the PHY stops the
> RX clock to save power. However, the stmmac hardware requires the RX
> clock to be running when accessing certain registers.
> 
> More specifically, VLAN operations fail with:
> 
>     # ip link add link end1 name end1.5 type vlan id 5
>     15c40000.ethernet end1: Timeout accessing MAC_VLAN_Tag_Filter
>     RTNETLINK answers: Device or resource busy
> 
> Also, LPI interrupt storms occur because the RX clock may be stopped when
> the driver attempts to clear the pending interrupt. The interrupt is
> not cleared and keeps re-triggering until the RX clock resumes.
> 
> A comprehensive overview of RX clock related issues in stmmac can be
> found in these threads:
> https://lore.kernel.org/all/20251026122905.29028-1-laurent.pinchart@ideasonboard.com/
> https://lore.kernel.org/all/Z9ySeo61VYTClIJJ@shell.armlinux.org.uk/
> 
> These issues are already fixed in mainline. This series backports the
> relevant stmmac EEE fixes to 6.1-cip.

I had a minor comment here, but that should be fixed in mainline,
first, so should not block the merge.

Reviewed-by: Pavel Machek <pavel@nabladev.com>

I can apply the series if it passes testing and there are no other
comments.

Best regards,
                                                                Pavel
-- 
In cooperation with Nabla.

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