Re: [PATCH] arm64: dts: imx8mp-debix-model-a: Disable EEE for 1000T

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Russell,

On Sat, Nov 22, 2025 at 09:57:49AM +0000, Russell King (Oracle) wrote:
> On Sat, Nov 22, 2025 at 04:22:46PM +0900, Laurent Pinchart wrote:
> > Hello Wei,
> > 
> > On Tue, Nov 18, 2025 at 01:50:55AM +0000, Wei Fang wrote:
> > > Sorry, I only have a little experience with DWMac, add Clark to help look
> > > at this issue.
> > 
> > Thank you.
> > 
> > I think we're getting close to having a good understanding of the
> > problem. I've debugged it as far as I could based on the information
> > available publicly. Let's try to get to the bottom of this issue, it
> > impacts quite a lot of people and it would be very nice to fix it
> > properly in mainline.
> > 
> > The short summary is that I'm experiencing an interrupt storm on IRQ 135
> > when EEE is enabled with the EQOS interface.
> > 
> > My current theory is that
> > 
> > - The lpi_intr_o signal of the EQOS is OR'ed into IRQ 135.
> > - The issue is triggerted by the PHY exiting LPI mode
> > - When it exits LPI mode, the PHY restarts generating the RX clock
> >   (clk_rx_i).
> > - The MAC detects exit from LPI, and asserts lpi_intr_o.
> > - Before the CPU has time to process the interrupt, the PHY enters LPI
> >   mode again, and stops generating the RX clock.
> > - The CPU processes the interrupt and reads the GMAC4_LPI_CTRL_STATUS
> >   registers. This does not clear lpi_intr_o as there's no clk_rx_i.
> 
> Please try setting STMMAC_FLAG_RX_CLK_RUNS_IN_LPI in dwmac-imx.c and
> see whether that changes the behaviour.

I have tested that and it worked like a charm ! I have submitted
https://lore.kernel.org/r/20251123053518.8478-1-laurent.pinchart@ideasonboard.com

That was quite an adventure. Thank you so much for all your support, I'm
not sure I would have managed without you (or at least I would have
needed way more time). I really really appreciate it.

If the above patch gets accepted, we will probably be able to remove the
eee-broken-* properties from the i.MX8MP device tree files (and possibly
from i.MX8DXL and i.MX93 as well). I have mentioned that below the
commit message of the patch, with a test procedure as it should be
tested on each board.

-- 
Regards,

Laurent Pinchart