Subject: Re: stmmac: TX stalls with head OWN=1; requiring manual DMA kick (6.12.63)

From: "Russell King (Oracle)" <[email-masked]>
Date: Wed, 11 Mar 2026 20:51:58 +0000

On Wed, Mar 11, 2026 at 08:46:04PM +0100, Andrew Lunn wrote:
> On Wed, Mar 11, 2026 at 08:34:36PM +0200, Tomer Maimon wrote:
> > Hi Giuseppe,
> > 
> > On kernel 6.12.63 (GMAC, normal 16‑byte TX descriptors), we observe
> > brief TX stalls when sending small packets.
> 
> You might want to look at Russell Kings patches from this week to
> rework the descriptor handling.
> 
> Also, please don't report problems on dead kernels. 6.12.76 is the
> current version for the 6.12 LTS. There is a small chance your problem
> has already been fixed, and you are wasting everybody's time.

Yep.

Not sure they'll materially affect any problem, because I try to avoid
functional changes in stuff like those.

What's missing from the original report is a description of the
hardware. stmmac drives multiple different versions of the Synopsys
IP which have significant changes between them. Which platform glue
is being used, which core driver is being used (dwmac1000? dwmac4?
etc.)

Also what isn't mentioned is whether this is a regression, or whether
it's something that has never worked. If it's a regression, which
kernel version previously worked?

-- 
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