Re: [PATCH 3/3] net: stmmac: Add DWMAC glue layer for Renesas GBETH

[Lad, Prabhakar]

Hi Russell,

On Sun, Mar 2, 2025 at 9:44 PM Russell King (Oracle)
<linux@xxxxxxxxxxxxxxx> wrote:
>
> On Sun, Mar 02, 2025 at 09:20:49PM +0000, Lad, Prabhakar wrote:
> > Hi Russell,
> > > What is the reason for setting this flag? If it's because of suspend/
> > > resume failures, does my "net: stmmac: fix resume failures due to
> > > RX clock" series solve this for you without requiring this flag?
> > >
> > Ive set this flag based on the configuration supported by this IP.
> > Unfortunately the platform which I am working on doesn't support s2r
> > yet so I cannot test suspend/resume path yet. But I do see an issue
> > when I unload and load just the glue module the DMA reset fails.
>
> Thanks for that feedback - that's a scenario I hadn't considered.
>
> I was trying to avoid having to disable LPI RX clock-stop on suspend by
> ensuring that it was enabled at resume time. I think that's valid, but
> you've brought up another similar scenario:
>
> - device is brought up, configures RX clock stop
> - links with media, negotiates EEE
> - driver is unloaded, link doesn't go down, but due to no traffic goes
>   into idle, so RX clock is stopped
> - driver reloaded, RX clock still stopped, reset fails
>
> I would like to solve that so we can get the power savings from
> stopping the clock, but still have reset work when necessary.
>
I would be happy to test the patches ;)

> I'm guessing that the "DMA reset fails" refers to this path:
>
> stmmac_open() -> __stmmac_open() -> stmmac_hw_setup() ->
> stmmac_init_dma_engine() -> stmmac_reset() ?
>
Yes.

> In other words, when the device is being brought back up
> adminsitratively?
>
> What happens if you (replace $if):
>
> # ip li set dev $if down
> # ip li set dev $if up
>
> Does that also fail without STMMAC_FLAG_RX_CLK_RUNS_IN_LPI set?
>
Logs without STMMAC_FLAG_RX_CLK_RUNS_IN_LPI flag set:
--------------------------------------------------------------
root@rzv2h-evk-alpha:~# ip li set dev eth1 down
[   33.606549] renesas-gbeth 15c40000.ethernet eth1: Link is Down
root@rzv2h-evk-alpha:~#
root@rzv2h-evk-alpha:~# ip li set dev eth0 down
[   37.356992] renesas-gbeth 15c30000.ethernet eth0: Link is Down
root@rzv2h-evk-alpha:~#
root@rzv2h-evk-alpha:~# ip li set dev eth1 up
[   43.974803] renesas-gbeth 15c40000.ethernet eth1: Register
MEM_TYPE_PAGE_POOL RxQ-0
[   43.983189] renesas-gbeth 15c40000.ethernet eth1: Register
MEM_TYPE_PAGE_POOL RxQ-1
[   43.991155] renesas-gbeth 15c40000.ethernet eth1: Register
MEM_TYPE_PAGE_POOL RxQ-2
[   43.999128] renesas-gbeth 15c40000.ethernet eth1: Register
MEM_TYPE_PAGE_POOL RxQ-3
[   44.072079] renesas-gbeth 15c40000.ethernet eth1: PHY [stmmac-1:00]
driver [Microchip KSZ9131 Gigabit PHY] (irq=POLL)
[   44.094605] dwmac4: Master AXI performs fixed burst length
[   44.100138] renesas-gbeth 15c40000.ethernet eth1: No Safety
Features support found
[   44.107748] renesas-gbeth 15c40000.ethernet eth1: IEEE 1588-2008
Advanced Timestamp supported
[   44.116725] renesas-gbeth 15c40000.ethernet eth1: registered PTP clock
[   44.123352] renesas-gbeth 15c40000.ethernet eth1: configuring for
phy/rgmii-id link mode
root@rzv2h-evk-alpha:~#
root@rzv2h-evk-alpha:~# ip li set dev eth1[   47.207761] renesas-gbeth
15c40000.ethernet eth1: Link is Up - 1Gbps/Full - flow control off
^C
root@rzv2h-evk-alpha:~# ^C
root@rzv2h-evk-alpha:~# ip li set dev eth0 up
[   55.636722] renesas-gbeth 15c30000.ethernet eth0: Register
MEM_TYPE_PAGE_POOL RxQ-0
[   55.645139] renesas-gbeth 15c30000.ethernet eth0: Register
MEM_TYPE_PAGE_POOL RxQ-1
[   55.653111] renesas-gbeth 15c30000.ethernet eth0: Register
MEM_TYPE_PAGE_POOL RxQ-2
[   55.661073] renesas-gbeth 15c30000.ethernet eth0: Register
MEM_TYPE_PAGE_POOL RxQ-3
[   55.732087] renesas-gbeth 15c30000.ethernet eth0: PHY [stmmac-0:00]
driver [Microchip KSZ9131 Gigabit PHY] (irq=POLL)
[   55.754612] dwmac4: Master AXI performs fixed burst length
[   55.760143] renesas-gbeth 15c30000.ethernet eth0: No Safety
Features support found
[   55.767740] renesas-gbeth 15c30000.ethernet eth0: IEEE 1588-2008
Advanced Timestamp supported
[   55.776705] renesas-gbeth 15c30000.ethernet eth0: registered PTP clock
[   55.783333] renesas-gbeth 15c30000.ethernet eth0: configuring for
phy/rgmii-id link mode
root@rzv2h-evk-alpha:~#
root@rzv2h-evk-alpha:~# [   58.855844] renesas-gbeth 15c30000.ethernet
eth0: tx_clk_stop=1
[   58.861989] renesas-gbeth 15c30000.ethernet eth0: Link is Up -
1Gbps/Full - flow control rx/tx

root@rzv2h-evk-alpha:~#
root@rzv2h-evk-alpha:~#

Logs with STMMAC_FLAG_RX_CLK_RUNS_IN_LPI flag set:
--------------------------------------------------------------
root@rzv2h-evk-alpha:~# ip li set dev eth1 down
[   30.053790] renesas-gbeth 15c40000.ethernet eth1: Link is Down
root@rzv2h-evk-alpha:~# ip li set dev eth0 down
[   35.366935] renesas-gbeth 15c30000.ethernet eth0: Link is Down
root@rzv2h-evk-alpha:~# ip li set dev eth1 up
[   40.448563] renesas-gbeth 15c40000.ethernet eth1: Register
MEM_TYPE_PAGE_POOL RxQ-0
[   40.456725] renesas-gbeth 15c40000.ethernet eth1: Register
MEM_TYPE_PAGE_POOL RxQ-1
[   40.464893] renesas-gbeth 15c40000.ethernet eth1: Register
MEM_TYPE_PAGE_POOL RxQ-2
[   40.472840] renesas-gbeth 15c40000.ethernet eth1: Register
MEM_TYPE_PAGE_POOL RxQ-3
[   40.543895] renesas-gbeth 15c40000.ethernet eth1: PHY [stmmac-1:00]
driver [Microchip KSZ9131 Gigabit PHY] (irq=POLL)
[   40.566419] dwmac4: Master AXI performs fixed burst length
[   40.571949] renesas-gbeth 15c40000.ethernet eth1: No Safety
Features support found
[   40.579550] renesas-gbeth 15c40000.ethernet eth1: IEEE 1588-2008
Advanced Timestamp supported
[   40.588505] renesas-gbeth 15c40000.ethernet eth1: registered PTP clock
[   40.595135] renesas-gbeth 15c40000.ethernet eth1: configuring for
phy/rgmii-id link mode
root@rzv2h-evk-alpha:~#
root@rzv2h-evk-alpha:~# [   43.687551] renesas-gbeth 15c40000.ethernet
eth1: Link is Up - 1Gbps/Full - flow control off

root@rzv2h-evk-alpha:~# ip li set dev eth0 up
[   49.644479] renesas-gbeth 15c30000.ethernet eth0: Register
MEM_TYPE_PAGE_POOL RxQ-0
[   49.652719] renesas-gbeth 15c30000.ethernet eth0: Register
MEM_TYPE_PAGE_POOL RxQ-1
[   49.660681] renesas-gbeth 15c30000.ethernet eth0: Register
MEM_TYPE_PAGE_POOL RxQ-2
[   49.669059] renesas-gbeth 15c30000.ethernet eth0: Register
MEM_TYPE_PAGE_POOL RxQ-3
[   49.740011] renesas-gbeth 15c30000.ethernet eth0: PHY [stmmac-0:00]
driver [Microchip KSZ9131 Gigabit PHY] (irq=POLL)
[   49.762518] dwmac4: Master AXI performs fixed burst length
[   49.768057] renesas-gbeth 15c30000.ethernet eth0: No Safety
Features support found
[   49.775655] renesas-gbeth 15c30000.ethernet eth0: IEEE 1588-2008
Advanced Timestamp supported
[   49.784609] renesas-gbeth 15c30000.ethernet eth0: registered PTP clock
[   49.791236] renesas-gbeth 15c30000.ethernet eth0: configuring for
phy/rgmii-id link mode
root@rzv2h-evk-alpha:~#
root@rzv2h-evk-alpha:~# [   52.871635] renesas-gbeth 15c30000.ethernet
eth0: tx_clk_stop=1
[   52.877777] renesas-gbeth 15c30000.ethernet eth0: Link is Up -
1Gbps/Full - flow control rx/tx


Cheers,
Prabhakar