Re: [PATCH 0/3] Add Aspeed AST2600 I3C support

From: Jeremy Kerr <jk@codeconstruct.com.au>
To: Dylan Hung <dylan_hung@aspeedtech.com>,
	alexandre.belloni@bootlin.com,  robh+dt@kernel.org,
	krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
	joel@jms.id.au, andrew@aj.id.au, p.zabel@pengutronix.de,
	 linux-i3c@lists.infradead.org, devicetree@vger.kernel.org,
	 linux-arm-kernel@lists.infradead.org,
	linux-aspeed@lists.ozlabs.org,  linux-kernel@vger.kernel.org
Cc: BMC-SW@aspeedtech.com, kobedylan@gmail.com
Subject: Re: [PATCH 0/3] Add Aspeed AST2600 I3C support
Date: Wed, 09 Aug 2023 08:07:58 +0800	[thread overview]
Message-ID: <d8d577e91779e045d5a2c7d701f65133a15b5d64.camel@codeconstruct.com.au> (raw)
In-Reply-To: <20230808154241.749641-1-dylan_hung@aspeedtech.com>

Hi Dylan,

> This patch series introduces the necessary changes to enable I3C
> support for the Aspeed AST2600 I3C controller. Specifically, it addresses the
> missing pinctrl configuration and reset control for the I3C
> functionality.

+1 for the pinctrl changes for the I3C1 and I3C2 controllers (I'll
review and ack separately). I have been testing on I3C3 and up, but just
not with the HVI3C on 1 & 2, hence no pinctrl definition there.

However, I don't think the other two are needed.

For 2/3 and 3/3, you're adding a reset control for the global register
block within the per-controller driver, but we can already do that on a
global basis with the existing syscon device. Hence this earlier change:

  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/mfd/syscon.c?id=7d1e3bd94828ad9fc86f55253cd6fec8edd65394

For this, I have:

    &i3c {
        i3c_global: i3c-global {
            compatible = "aspeed,ast2600-i3c-global", "simple-mfd", "syscon";
            resets = <&syscon ASPEED_RESET_I3C_DMA>;
            reg = <0x0 0x1000>;
        };

        i3c2: i3c-master@4000 {
            compatible = "aspeed,ast2600-i3c";
            reg = <0x4000 0x1000>;
            clocks = <&syscon ASPEED_CLK_GATE_I3C2CLK>;
            pinctrl-names = "default";
            pinctrl-0 = <&pinctrl_i3c3_default>;
            interrupts = <GIC_SPI 104 IRQ_TYPE_LEVEL_HIGH>;
            aspeed,global-regs = <&i3c_global 2>;
            status = "disabled";
        };

        /* ... */
    };

- with no changes needed to any bindings. I haven't needed any other
resets; are there per-controller resets specified in the HW docs you
have?

Does that work for you? If you'd like to test, feel free to use my
sample dts at:

  https://github.com/CodeConstruct/linux/commit/05cac24705fa62d2176ecbbbf15d955cfe86e753

Cheers,

Jeremy

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