From: Chen-Yu Tsai <wens@csie.org>
To: "André Przywara" <andre.przywara@arm.com>
Cc: Samuel Holland <samuel@sholland.org>,
Maxime Ripard <mripard@kernel.org>,
Jernej Skrabec <jernej.skrabec@siol.net>,
devicetree <devicetree@vger.kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-sunxi <linux-sunxi@googlegroups.com>,
Rob Herring <robh+dt@kernel.org>,
Icenowy Zheng <icenowy@aosc.xyz>,
Yangtao Li <frank@allwinnertech.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [linux-sunxi] Re: [PATCH 7/8] arm64: dts: allwinner: Add Allwinner H616 .dtsi file
Date: Fri, 4 Dec 2020 00:20:57 +0800 [thread overview]
Message-ID: <CAGb2v65KL=Bsv-GC2FOt24wZRX3Ta+VQ44eeSs1Kt32EGBv+yg@mail.gmail.com> (raw)
In-Reply-To: <3dc67c21-f649-cca5-ec54-c639c54ee56a@arm.com>
On Thu, Dec 3, 2020 at 11:45 PM André Przywara <andre.przywara@arm.com> wrote:
>
> On 03/12/2020 15:02, Chen-Yu Tsai wrote:
> > On Thu, Dec 3, 2020 at 6:54 PM André Przywara <andre.przywara@arm.com> wrote:
> >>
> >> On 03/12/2020 03:16, Samuel Holland wrote:
> >>
> >> Hi,
> >>
> >>> On 12/2/20 7:54 AM, Andre Przywara wrote:
> >>> ...
> >>>> + soc {
> >>>> + compatible = "simple-bus";
> >>>> + #address-cells = <1>;
> >>>> + #size-cells = <1>;
> >>>> + ranges = <0x0 0x0 0x0 0x40000000>;
> >>>> +
> >>>> + syscon: syscon@3000000 {
> >>>> + compatible = "allwinner,sun50i-h616-system-control",
> >>>> + "allwinner,sun50i-a64-system-control";
> >>>> + reg = <0x03000000 0x1000>;
> >>>> + #address-cells = <1>;
> >>>> + #size-cells = <1>;
> >>>> + ranges;
> >>>> +
> >>>> + sram_c: sram@28000 {
> >>>> + compatible = "mmio-sram";
> >>>> + reg = <0x00028000 0x30000>;
> >>>> + #address-cells = <1>;
> >>>> + #size-cells = <1>;
> >>>> + ranges = <0 0x00028000 0x30000>;
> >>>> + };
> >>>> +
> >>>> + sram_c1: sram@1a00000 {
> >>>> + compatible = "mmio-sram";
> >>>> + reg = <0x01a00000 0x200000>;
> >>>> + #address-cells = <1>;
> >>>> + #size-cells = <1>;
> >>>> + ranges = <0 0x01a00000 0x200000>;
> >>>> +
> >>>> + ve_sram: sram-section@0 {
> >>>> + compatible = "allwinner,sun50i-h616-sram-c1",
> >>>> + "allwinner,sun4i-a10-sram-c1";
> >>>> + reg = <0x000000 0x200000>;
> >>>> + };
> >>>> + };
> >>>> + };
> >>>
> >>> You mentioned that you could not find a SRAM A2. How were these SRAM ranges
> >>> verified? If you can load eGON.BT0 larger than 32 KiB, then presumably NBROM
> >>> uses SRAM C, and it is in the manual, but I see no mention of SRAM C1.
> >>
> >> The manual says that SRAM C *can* be used by "the system", at boot time,
> >> as long as it's configured correctly. I couldn't find any details on how
> >> to switch clock sources for SRAM C, and the manual stanza on this is
> >> quite gibberish. I presume it's configured either by BROM or by reset
> >> default this way. I think the idea is that the later users (VE, DE) take
> >> ownership at some point (which means we can't run any firmware in there).
> >> The BSP boot0 is 48KB already, so reaching into SRAM C, and the code
> >> itself heavily uses SRAM C (found by hacking boot0 to drop to FEL and
> >> inspecting the memory afterwards).
> >>
> >> For C1: I copied this name from the H6 .dtsi, the manual calls this
> >> "VE-SRAM", in both manuals, and the description looks identical there
> >> for both SoCs. I think this will be later used by the video engine, so I
> >> kept it in. The large size made me suspicious, and from former
> >> experiments it looks like being aliased to (parts of) SRAM C.
> >
> > I would just call it sram_ve or ve_sram. SRAM C1 would make more sense if
> > it were part of SRAM C, not the other way around.
>
> But isn't that what we do? "sram_c1" is just the node name alias used
> for the parent node. That is actually never referenced anywhere (in any
> of the the H6 .dts), so we can actually remove it, I guess.
> The actual SRAM section is called ve_sram already.
This is what I had in mind:
syscon: {
sram_c: sram@28000 {
compatible = "mmio-sram";
reg = <0x00028000 0x30000>;
#address-cells = <1>;
#size-cells = <1>;
ranges = <0 0x00028000 0x30000>;
/* starting address might not be correct */
sram_c_ve: sram-section@0 {
compatible = "allwinner,sun50i-h616-ve-sram-c",
"allwinner,sun4i-a10-sram-c1";
/* 64 kiB borrowed from ve_sram */
reg = <0x0 0x10000>;
};
};
ve_sram: sram@1a00000 {
compatible = "mmio-sram";
reg = <0x01a00000 0x200000>;
#address-cells = <1>;
#size-cells = <1>;
};
};
Another variant, trying to describe the aliasing, though it seems
quite confusing:
syscon: {
ve_sram: sram@1a00000 {
compatible = "mmio-sram";
reg = <0x01a00000 0x200000>;
#address-cells = <1>;
#size-cells = <1>;
ranges;
ve_sram_c: sram-section@28000 {
compatible = "allwinner,sun50i-h616-ve-sram-c",
"allwinner,sun4i-a10-sram-c1";
reg = <0x28000 0x10000>;
};
};
};
Just out of curiosity, is the whole SRAM @1a00000 accessible by the CPU?
Does it require the system control SRAM bits to be set, or does that only
affect the portion that SRAM C "borrows"? If it isn't accessible to the
CPU at all, then we might as well not put it in the device tree.
> And I can't change the compatible name, for the fallback, at least.
>
> I can make the new compatible string read
> "allwinner,sun50i-h616-ve-sram", if that helps, but that would mean
> deviating from the H6 and other SoCs.
Matching what the documents say makes more sense to me.
Regards
ChenYu
> Cheers,
> Andre
>
>
> >
> > Also the sram-section node would make more sense if it were in sram_c, as
> > that is the part that gets switched around, not the full region @ 1a00000.
> >
> > ChenYu
> >
> >> Maybe some guys with more VE knowledge can shine some light on this?
> >>
> >> Cheers,
> >> Andre
> >>
>
> --
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next prev parent reply other threads:[~2020-12-03 16:22 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-02 13:54 [PATCH 0/8] arm64: sunxi: Initial Allwinner H616 SoC support Andre Przywara
2020-12-02 13:54 ` [PATCH 1/8] clk: sunxi-ng: h6: Fix clock divider range on some clocks Andre Przywara
2020-12-02 16:17 ` Jernej Škrabec
2020-12-02 13:54 ` [PATCH 2/8] pinctrl: sunxi: Add support for the Allwinner H616 pin controller Andre Przywara
2020-12-02 15:52 ` Maxime Ripard
2020-12-05 22:41 ` Linus Walleij
2020-12-02 18:15 ` Jernej Škrabec
2020-12-06 12:32 ` [linux-sunxi] " Clément Péron
2020-12-06 12:42 ` Jernej Škrabec
2020-12-06 14:52 ` André Przywara
2020-12-06 16:01 ` Icenowy Zheng
2020-12-07 1:07 ` André Przywara
2020-12-07 1:45 ` André Przywara
2020-12-13 16:27 ` Icenowy Zheng
2020-12-14 9:26 ` Chen-Yu Tsai
2020-12-02 13:54 ` [PATCH 3/8] pinctrl: sunxi: Add support for the Allwinner H616-R " Andre Przywara
2020-12-02 15:54 ` Maxime Ripard
2020-12-02 17:55 ` Jernej Škrabec
2020-12-02 13:54 ` [PATCH 4/8] clk: sunxi-ng: Add support for the Allwinner H616 R-CCU Andre Przywara
2020-12-02 14:31 ` Icenowy Zheng
2020-12-03 11:07 ` André Przywara
2020-12-03 14:02 ` [linux-sunxi] " Icenowy Zheng
2020-12-02 18:20 ` Jernej Škrabec
2020-12-03 2:44 ` Samuel Holland
2020-12-03 10:52 ` André Przywara
2020-12-02 13:54 ` [PATCH 5/8] clk: sunxi-ng: Add support for the Allwinner H616 CCU Andre Przywara
2020-12-02 15:56 ` Maxime Ripard
2020-12-02 21:03 ` Jernej Škrabec
2020-12-02 23:06 ` André Przywara
2020-12-05 16:36 ` [linux-sunxi] " Icenowy Zheng
2020-12-09 14:33 ` [linux-sunxi] " Clément Péron
2020-12-09 21:35 ` André Przywara
2020-12-09 22:20 ` Jernej Škrabec
2020-12-09 22:45 ` André Przywara
2020-12-10 13:31 ` Icenowy Zheng
2020-12-10 14:34 ` André Przywara
2020-12-02 13:54 ` [PATCH 6/8] mmc: sunxi: add support for A100 mmc controller Andre Przywara
2020-12-02 13:54 ` [PATCH 7/8] arm64: dts: allwinner: Add Allwinner H616 .dtsi file Andre Przywara
2020-12-02 16:03 ` Icenowy Zheng
2020-12-02 16:19 ` André Przywara
2020-12-02 16:05 ` Maxime Ripard
2020-12-02 16:13 ` Icenowy Zheng
2020-12-03 3:10 ` Samuel Holland
2020-12-02 16:33 ` Jernej Škrabec
2020-12-03 1:35 ` André Przywara
2020-12-03 3:16 ` Samuel Holland
2020-12-03 10:53 ` André Przywara
2020-12-03 15:02 ` [linux-sunxi] " Chen-Yu Tsai
2020-12-03 15:44 ` André Przywara
2020-12-03 16:20 ` Chen-Yu Tsai [this message]
2020-12-08 0:47 ` André Przywara
2020-12-02 13:54 ` [PATCH 8/8] arm64: dts: allwinner: Add OrangePi Zero 2 .dts Andre Przywara
2020-12-02 15:57 ` Icenowy Zheng
2020-12-02 16:43 ` André Przywara
2020-12-02 16:07 ` Maxime Ripard
2020-12-02 16:25 ` Jernej Škrabec
2020-12-06 12:51 ` [linux-sunxi] " Clément Péron
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