From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E2D8F1F947 for ; Mon, 13 Nov 2023 13:21:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ru41IK3O" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AB0CC433C9; Mon, 13 Nov 2023 13:21:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699881682; bh=KCjtPGRJNG1e0l55yc9Fl85FksaID/z/6qmz2c02TJs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ru41IK3OjWDOaCHPpcYqHm3fHFO5FRHCFL0FJbo2Y83ZKmHP5bOm4QNc0vImoxxh5 W8pK8ec66mMOEZBcl8QQcycHoQnP856N2TWp7LHx/gHrqCaRceS6nMqi1jMaOwGVvm rOtTxdv3Njs+wM3stEj2CqnL8iTNdldYRY8NVzI8X+KTlq8c6eUbv6nqwkjGXVcGlb REiwdE5bkoAOYhBkj6CMue73qy43GrBvQwiGq46F9CDBJDUyr0PFVOz5gPJTbbH7B0 wP2KaM6MUkDyVjrmQdkTCNG5teii+HJdqM2PsT2Xlskh3Cnw8DrqLu+VJzUvndBeZB ne0EleduG7Q0Q== Date: Mon, 13 Nov 2023 21:09:01 +0800 From: Jisheng Zhang To: Samuel Holland Cc: Philipp Zabel , Rob Herring , Krzysztof Kozlowski , Conor Dooley , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Chao Wei , Chen Wang Subject: Re: [PATCH 4/4] riscv: dts: sophgo: add reset phandle to all uart nodes Message-ID: References: <20231113005503.2423-1-jszhang@kernel.org> <20231113005503.2423-5-jszhang@kernel.org> <95c20c6c-66cd-4f87-920b-5da766317e19@sifive.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <95c20c6c-66cd-4f87-920b-5da766317e19@sifive.com> On Sun, Nov 12, 2023 at 09:04:55PM -0500, Samuel Holland wrote: > Hi Jisheng, > > On 2023-11-12 6:55 PM, Jisheng Zhang wrote: > > Although, the resets are deasserted by default. Add them for > > completeness. > > > > Signed-off-by: Jisheng Zhang > > --- > > arch/riscv/boot/dts/sophgo/cv1800b.dtsi | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/arch/riscv/boot/dts/sophgo/cv1800b.dtsi b/arch/riscv/boot/dts/sophgo/cv1800b.dtsi > > index 4032419486be..e04df04a91c0 100644 > > --- a/arch/riscv/boot/dts/sophgo/cv1800b.dtsi > > +++ b/arch/riscv/boot/dts/sophgo/cv1800b.dtsi > > @@ -4,6 +4,7 @@ > > */ > > > > #include > > +#include > > > > / { > > compatible = "sophgo,cv1800b"; > > @@ -65,6 +66,7 @@ uart0: serial@4140000 { > > reg = <0x04140000 0x100>; > > interrupts = <44 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&osc>; > > + resets = <&rst RST_UART0>; > > Since it's not obvious: this breaks devicetree forward compatibility. An > existing kernel will fail the devm_reset_control_get_optional_exclusive() in > 8250_dw.c because it has no driver for the reset controller. > > This may not be a concern yet, since the devicetree is still "in development". > But it is something to keep in mind for the future. To avoid this sort of > problem, it's best to fully model the clocks/resets/other dependencies as early > as possible, and not rely on the firmware setting anything up. Thank you. This may be discussed before, "DT backward compatibility is a must while forward compatibility is optional"? maybe I'm wrong. And Indeed, it's better if we can have forward compatibility, will take care this in future. > > Regards, > Samuel > > > reg-shift = <2>; > > reg-io-width = <4>; > > status = "disabled"; > > @@ -75,6 +77,7 @@ uart1: serial@4150000 { > > reg = <0x04150000 0x100>; > > interrupts = <45 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&osc>; > > + resets = <&rst RST_UART1>; > > reg-shift = <2>; > > reg-io-width = <4>; > > status = "disabled"; > > @@ -85,6 +88,7 @@ uart2: serial@4160000 { > > reg = <0x04160000 0x100>; > > interrupts = <46 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&osc>; > > + resets = <&rst RST_UART2>; > > reg-shift = <2>; > > reg-io-width = <4>; > > status = "disabled"; > > @@ -95,6 +99,7 @@ uart3: serial@4170000 { > > reg = <0x04170000 0x100>; > > interrupts = <47 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&osc>; > > + resets = <&rst RST_UART3>; > > reg-shift = <2>; > > reg-io-width = <4>; > > status = "disabled"; > > @@ -105,6 +110,7 @@ uart4: serial@41c0000 { > > reg = <0x041c0000 0x100>; > > interrupts = <48 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&osc>; > > + resets = <&rst RST_UART4>; > > reg-shift = <2>; > > reg-io-width = <4>; > > status = "disabled"; >