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Date:   Fri, 29 Apr 2022 14:14:56 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     "jay.xu@rock-chips.com" <jay.xu@rock-chips.com>
Cc:     kuba <kuba@kernel.org>, davem <davem@davemloft.net>,
        joabreu <joabreu@synopsys.com>,
        "alexandre.torgue" <alexandre.torgue@st.com>,
        "peppe.cavallaro" <peppe.cavallaro@st.com>,
        netdev <netdev@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@lists.infradead.org>,
        Device Tree <devicetree@vger.kernel.org>
Subject: Re: Re: [PATCH V2] ethernet: stmmac: support driver work for DTs
 without child queue node
Message-ID: <YmvWwIgE71iwZhgp@lunn.ch>
References: <20220428010927.526310-1-jay.xu@rock-chips.com>
 <20220429004605.1010751-1-jay.xu@rock-chips.com>
 <Yms3ynT8RGmldAkm@lunn.ch>
 <2022042909545741446644@rock-chips.com>
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Adding device tree list.

This is mostly a device tree issue, so the device tree Maintainers
should be part of the discussion.

> >On Fri, Apr 29, 2022 at 08:46:05AM +0800, Jianqun Xu wrote:
> >> The driver use the value of property 'snps,rx-queues-to-use' to loop
> >> same numbers child nodes as queues, such as:
> >>
> >>???? gmac {
> >>???????? rx-queues-config {
> >>???????????? snps,rx-queues-to-use = <1>;
> >>???????????? queue0 {
> >>???????????????? // nothing need here.
> >> ??? };
> >> };
> >>???? };
> >>
> >> Since a patch for dtc from rockchip will delete all node without any
> >> properties or child node, the queue0 node will be deleted, that caused
> >> the driver fail to probe:
> >
> >Is this the in tree dtc? Do you have a commit hash for it? That should
> >probably be used as a Fixes: tag. Or that change to dtc needs
> >reverting because it breaks stuff.
> > 
> The patch is a hack patch for some products and have not in tree dtc, I said that to
> explain a possible case how things happed, it's only a case of no child queue node.

So this has nothing to do with the kernel dtc, or the upstream
dtc. This is only a 'vendor crap' dtc which has been hacked?

Why should mainline care? Is there anything in the DT standard which
says the compiler can optimise out empty properties?

     Andrew