From: Conor Dooley <conor@kernel.org>
To: Chen Wang <unicornxw@gmail.com>
Cc: Conor Dooley <conor.dooley@microchip.com>,
aou@eecs.berkeley.edu, chao.wei@sophgo.com,
devicetree@vger.kernel.org, emil.renner.berthing@canonical.com,
guoren@kernel.org, jszhang@kernel.org,
krzysztof.kozlowski+dt@linaro.org, linux-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org, palmer@dabbelt.com,
paul.walmsley@sifive.com, robh+dt@kernel.org,
xiaoguang.xing@sophgo.com, Chen Wang <wangchen20@iscas.ac.cn>,
Inochi Amaoto <inochiama@outlook.com>
Subject: Re: [PATCH v2 09/11] riscv: dts: add initial SOPHGO SG2042 SoC device tree
Date: Thu, 21 Sep 2023 13:06:20 +0100 [thread overview]
Message-ID: <20230921-fdc47972b1d3caa685f2a164@fedora> (raw)
In-Reply-To: <CAHAQgRDLmKJQ1sp76q4s7P4E_=nYuw199ceGCR0LYeq3331tLQ@mail.gmail.com>
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On Thu, Sep 21, 2023 at 06:27:09PM +0800, Chen Wang wrote:
> Conor Dooley <conor@kernel.org> 于2023年9月21日周四 18:15写道：
> >
> > On Thu, Sep 21, 2023 at 05:56:28PM +0800, Chen Wang wrote:
> > > > > +
> > > > > +/ {
> > > > > + compatible = "sophgo,sg2042";
> > > > > + #address-cells = <2>;
> > > > > + #size-cells = <2>;
> > > > > + dma-noncoherent;
> > > > > +
> > > > > + aliases {
> > > > > + serial0 = &uart0;
> > > > > + };
> > > > > +
> > > > > + /* the mem node will be updated by ZSBL. */
> > > >
> > > > huh? So these are random numbers below? Either put something useful here
> > > > or delete it please.
> > >
> > > The memory for SG2042 is not fixed, the bootloader will detect memory
> > > installed on board during booting and fill the actual address and size
> > > in the memory node. The comment " /* the mem node will be updated by
> > > ZSBL. */" is telling this.
> >
> > Yes, I read the comment!
> >
> > > We write memory nodes like this to make them act just as placeholders
> > > and the value is by default written as zero.
> >
> > Why knowingly add something that is wrong, rather than omitting them
> > entirely?
>
> We learn this from arch/arm64/boot/dts/hisilicon/hi3660-hikey960.dts,
> it writes DTS as following:
>
> ```
> memory@0 {
> device_type = "memory";
> /* rewrite this at bootloader */
> reg = <0x0 0x0 0x0 0x0>;
> };
> ```
> So you mean we can totally remove the memory nodes in DTS and make
> bootloader add it by itself? That sounds a good idea, I will have a
> try. I used to think memory nodes are must-have in DTS.
AFAIR, the ones for the d1 based systems (like the nezha I have) don't
have a memory node at all.
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next prev parent reply other threads:[~2023-09-21 12:06 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-20 6:33 [PATCH v2 00/11] Add Milk-V Pioneer RISC-V board support Chen Wang
2023-09-20 6:34 ` [PATCH v2 01/11] riscv: Add SOPHGO SOC family Kconfig support Chen Wang
2023-09-20 7:34 ` Guo Ren
2023-09-20 8:21 ` Conor Dooley
2023-09-20 6:37 ` [PATCH v2 02/11] dt-bindings: vendor-prefixes: add milkv/sophgo Chen Wang
2023-09-20 7:38 ` Guo Ren
2023-09-20 8:22 ` Conor Dooley
2023-09-20 9:14 ` Chen Wang
2023-09-20 6:37 ` [PATCH v2 03/11] dt-bindings: riscv: add sophgo sg2042 bindings Chen Wang
2023-09-20 7:43 ` Guo Ren
2023-09-20 8:28 ` Conor Dooley
2023-09-21 10:21 ` Chen Wang
2023-09-21 12:18 ` Conor Dooley
2023-09-21 13:40 ` Chen Wang
2023-09-21 13:51 ` Chen Wang
2023-09-21 14:00 ` Conor Dooley
2023-09-22 1:48 ` Chen Wang
2023-09-20 11:55 ` Krzysztof Kozlowski
2023-09-20 12:03 ` 汪辰
2023-09-21 0:48 ` Jisheng Zhang
2023-09-20 6:38 ` [PATCH v2 04/11] dt-bindings: riscv: Add T-HEAD C920 compatibles Chen Wang
2023-09-20 7:44 ` Guo Ren
2023-09-20 8:37 ` Conor Dooley
2023-09-20 6:39 ` [PATCH v2 05/11] dt-bindings: interrupt-controller: Add SOPHGO's SG2042 PLIC Chen Wang
2023-09-20 7:45 ` Guo Ren
2023-09-20 8:57 ` Conor Dooley
2023-09-20 6:39 ` [PATCH v2 06/11] dt-bindings: timer: Add Sophgo sg2042 clint Chen Wang
2023-09-20 8:12 ` Guo Ren
2023-09-20 8:50 ` Conor Dooley
2023-09-20 11:57 ` Krzysztof Kozlowski
2023-09-20 6:39 ` [PATCH v2 07/11] dt-bindings: serial: snps-dw-apb-uart: Add Sophgo SG2042 uarts Chen Wang
2023-09-20 7:51 ` Guo Ren
2023-09-20 8:37 ` Conor Dooley
2023-09-20 6:40 ` [PATCH v2 08/11] serial: 8250_dw: Add Sophgo SG2042 support Chen Wang
2023-09-20 7:53 ` Guo Ren
2023-09-20 8:05 ` Chen Wang
2023-09-20 8:08 ` Guo Ren
2023-09-22 9:41 ` Ben Dooks
2023-09-22 10:40 ` Emil Renner Berthing
2023-09-22 11:39 ` Chen Wang
2023-09-26 7:38 ` Chen Wang
2023-09-20 6:40 ` [PATCH v2 09/11] riscv: dts: add initial SOPHGO SG2042 SoC device tree Chen Wang
2023-09-20 8:04 ` Guo Ren
2023-09-20 8:57 ` Conor Dooley
2023-09-21 9:56 ` Chen Wang
2023-09-21 10:15 ` Conor Dooley
2023-09-21 10:27 ` Chen Wang
2023-09-21 12:06 ` Conor Dooley [this message]
2023-09-20 11:32 ` Emil Renner Berthing
2023-09-20 12:09 ` 汪辰
2023-09-20 12:32 ` Emil Renner Berthing
2023-09-20 12:37 ` 汪辰
2023-09-20 15:19 ` Palmer Dabbelt
2023-09-20 15:31 ` Conor Dooley
2023-09-20 6:40 ` [PATCH v2 10/11] riscv: dts: sophgo: add Milk-V Pioneer board " Chen Wang
2023-09-20 8:05 ` Guo Ren
2023-09-20 8:16 ` Conor Dooley
2023-09-20 11:59 ` Krzysztof Kozlowski
2023-09-20 6:41 ` [PATCH v2 11/11] riscv: defconfig: enable SOPHGO SoC Chen Wang
2023-09-20 8:06 ` Guo Ren
2023-09-20 8:58 ` Conor Dooley
2023-09-20 10:01 ` [PATCH v2 00/11] Add Milk-V Pioneer RISC-V board support Conor Dooley
2023-09-22 10:24 ` Chen Wang
2023-09-22 10:50 ` Conor Dooley
2023-09-22 11:28 ` Chen Wang
2023-09-20 15:22 ` Palmer Dabbelt
2023-09-26 10:29 ` Chen Wang
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