-----Original Message-----
From: Russell King <linux@armlinux.org.uk>
Sent: Tuesday, August 1, 2023 7:57 AM
To: Johannes Zink <redacted>
Cc: Shenwei Wang <shenwei.wang@nxp.com>; David S. Miller
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Subject: [EXT] Re: [PATCH v3 net 2/2] net: stmmac: dwmac-imx: pause the TXC
clock in fixed-link

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On Tue, Aug 01, 2023 at 02:47:46PM +0200, Johannes Zink wrote:

quoted

Hi Shenwei,

thanks for your patch.

On 7/31/23 18:19, Shenwei Wang wrote:

quoted

When using a fixed-link setup, certain devices like the SJA1105
require a small pause in the TXC clock line to enable their internal
tunable delay line (TDL).

If this is only required for some devices, is it safe to enforce this
behaviour unconditionally for any kind of fixed link devices connected
to the MX93 EQOS or could this possibly break for other devices?

This same point has been raised by Andrew Halaney in message-id
<4govb566nypifbtqp5lcbsjhvoyble5luww3onaa2liinboguf@4kgihys6vhrg>
and Fabio Estevam in message-id

<CAOMZO5ANQmVbk_jy7qdVtzs3716FisT2c72W+3WZyu7FoAochw@mail.gmail.
com>
but we don't seem to have any answer for it.

Hi Russell,

I hope you have thoroughly read all of my earlier responses, as I believe I already addressed this question.
I'm happy to clarify further, but kindly avoid unsubstantiated comments.

https://lore.kernel.org/imx/20230727152503.2199550-1-shenwei.wang@nxp.com/T/#m08da3797a056d4d8ea4c1d8956b445ae967e7cfa (local)
" Yes, that's the purpose because it won't hurt even the other side is not SJA1105."

Also, the patch still uses wmb() between the write and the delay, and as Will
Deacon pointed out in his message, message-id
<20230728153611.GH21718@willie-the-truck>
this is not safe, yet still a new version was sent.

Can we conclude that even without the wmb() here, the desired delay time between
operations can still be ensured?

Thanks,
Shenwei

It seems the author of these patches is pretty resistant to comments, and has
shown that when I was requesting changes - it was an awful struggle to get
changes made. I'm now of the opinion that I really can't be bothered to review
these patches, precisely because feedback is clearly not welcome or if welcome,
apparently acted upon.

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