Re: Re: [PATCH V2] ethernet: stmmac: support driver work for DTs without child queue node

From: "jay.xu@rock-chips.com" <jay.xu@rock-chips.com>
To: "Andrew Lunn" <andrew@lunn.ch>
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>,
	 devicetree <devicetree@vger.kernel.org>
Subject: Re: Re: [PATCH V2] ethernet: stmmac: support driver work for DTs without child queue node
Date: Sun, 1 May 2022 09:40:37 +0800	[thread overview]
Message-ID: <2022050109403682292448@rock-chips.com> (raw)
In-Reply-To: YmvWwIgE71iwZhgp@lunn.ch

Hi Andrew

--------------
jay.xu@rock-chips.com
>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? 

Yes, it't nothing about what kind of dtc, does about what rule for properties, now the one property
request another child node must exist and number of child node must equal to the value of the property,
the 
#address-cells = <1>;
#size-cells = <1>;
does this but they are in special key words, the gmac has no likely key word.

>
>     Andrew
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