netdev - RE: [EXT] Re: [PATCH v3 net 2/2] net: stmmac: dwmac-imx: pause the TXC clock in fixed-link

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Message-ID:
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Date: Tue, 1 Aug 2023 17:06:46 +0000
From: Shenwei Wang <shenwei.wang@....com>
To: Russell King <linux@...linux.org.uk>, Johannes Zink
	<j.zink@...gutronix.de>
CC: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Maxime Coquelin <mcoquelin.stm32@...il.com>, Shawn Guo
	<shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, Neil Armstrong
	<neil.armstrong@...aro.org>, Kevin Hilman <khilman@...libre.com>, Vinod Koul
	<vkoul@...nel.org>, Chen-Yu Tsai <wens@...e.org>, Jernej Skrabec
	<jernej.skrabec@...il.com>, Samuel Holland <samuel@...lland.org>, Giuseppe
 Cavallaro <peppe.cavallaro@...com>, Alexandre Torgue
	<alexandre.torgue@...s.st.com>, Jose Abreu <joabreu@...opsys.com>,
	Pengutronix Kernel Team <kernel@...gutronix.de>, Fabio Estevam
	<festevam@...il.com>, dl-linux-imx <linux-imx@....com>, Jerome Brunet
	<jbrunet@...libre.com>, Martin Blumenstingl
	<martin.blumenstingl@...glemail.com>, Bhupesh Sharma
	<bhupesh.sharma@...aro.org>, Nobuhiro Iwamatsu
	<nobuhiro1.iwamatsu@...hiba.co.jp>, Simon Horman <simon.horman@...igine.com>,
	Andrew Halaney <ahalaney@...hat.com>, Bartosz Golaszewski
	<bartosz.golaszewski@...aro.org>, Wong Vee Khee <veekhee@...le.com>, Revanth
 Kumar Uppala <ruppala@...dia.com>, Jochen Henneberg
	<jh@...neberg-systemdesign.com>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "linux-stm32@...md-mailman.stormreply.com"
	<linux-stm32@...md-mailman.stormreply.com>,
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	<linux-kernel@...r.kernel.org>, "linux-amlogic@...ts.infradead.org"
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	<imx@...ts.linux.dev>, Frank Li <frank.li@....com>
Subject: RE: [EXT] Re: [PATCH v3 net 2/2] net: stmmac: dwmac-imx: pause the
 TXC clock in fixed-link



> -----Original Message-----
> From: Russell King <linux@...linux.org.uk>
> Sent: Tuesday, August 1, 2023 7:57 AM
> To: Johannes Zink <j.zink@...gutronix.de>
> Cc: Shenwei Wang <shenwei.wang@....com>; David S. Miller
> <davem@...emloft.net>; Eric Dumazet <edumazet@...gle.com>; Jakub
> Kicinski <kuba@...nel.org>; Paolo Abeni <pabeni@...hat.com>; Maxime
> Coquelin <mcoquelin.stm32@...il.com>; Shawn Guo <shawnguo@...nel.org>;
> Sascha Hauer <s.hauer@...gutronix.de>; Neil Armstrong
> <neil.armstrong@...aro.org>; Kevin Hilman <khilman@...libre.com>; Vinod
> Koul <vkoul@...nel.org>; Chen-Yu Tsai <wens@...e.org>; Jernej Skrabec
> <jernej.skrabec@...il.com>; Samuel Holland <samuel@...lland.org>;
> Giuseppe Cavallaro <peppe.cavallaro@...com>; Alexandre Torgue
> <alexandre.torgue@...s.st.com>; Jose Abreu <joabreu@...opsys.com>;
> Pengutronix Kernel Team <kernel@...gutronix.de>; Fabio Estevam
> <festevam@...il.com>; dl-linux-imx <linux-imx@....com>; Jerome Brunet
> <jbrunet@...libre.com>; Martin Blumenstingl
> <martin.blumenstingl@...glemail.com>; Bhupesh Sharma
> <bhupesh.sharma@...aro.org>; Nobuhiro Iwamatsu
> <nobuhiro1.iwamatsu@...hiba.co.jp>; Simon Horman
> <simon.horman@...igine.com>; Andrew Halaney <ahalaney@...hat.com>;
> Bartosz Golaszewski <bartosz.golaszewski@...aro.org>; Wong Vee Khee
> <veekhee@...le.com>; Revanth Kumar Uppala <ruppala@...dia.com>; Jochen
> Henneberg <jh@...neberg-systemdesign.com>; netdev@...r.kernel.org; linux-
> stm32@...md-mailman.stormreply.com; linux-arm-kernel@...ts.infradead.org;
> linux-kernel@...r.kernel.org; linux-amlogic@...ts.infradead.org;
> imx@...ts.linux.dev; Frank Li <frank.li@....com>
> 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:
> > Hi Shenwei,
> >
> > thanks for your patch.
> >
> > On 7/31/23 18:19, Shenwei Wang wrote:
> > > 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@...ihys6vhrg>
> and Fabio Estevam in message-id
>
> <CAOMZO5ANQmVbk_jy7qdVtzs3716FisT2c72W+3WZyu7FoAochw@...l.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
" 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@...lie-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.
>
> --
> RMK's Patch system:
> https://www.ar/
> mlinux.org.uk%2Fdeveloper%2Fpatches%2F&data=05%7C01%7Cshenwei.wang
> %40nxp.com%7Ce65ab380ff5b4748da5308db928ec751%7C686ea1d3bc2b4c6fa
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