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Message-ID: <1444dac5-c725-4bf7-8843-469a62c3abf1@bootlin.com>
Date: Thu, 2 May 2024 09:47:43 +0200
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Subject: Re: [PATCH RFC v2 4/4] riscv: dts: thead: Add clock to TH1520 mmc
 controllers
To: Drew Fustini <dfustini@tenstorrent.com>,
 Jisheng Zhang <jszhang@kernel.org>, Guo Ren <guoren@kernel.org>,
 Fu Wei <wefu@redhat.com>, Yangtao Li <frank.li@vivo.com>,
 Emil Renner Berthing <emil.renner.berthing@canonical.com>,
 Michael Turquette <mturquette@baylibre.com>, Stephen Boyd
 <sboyd@kernel.org>, Rob Herring <robh@kernel.org>,
 Krzysztof Kozlowski <krzk+dt@kernel.org>, Conor Dooley
 <conor+dt@kernel.org>, Paul Walmsley <paul.walmsley@sifive.com>,
 Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>
Cc: linux-riscv@lists.infradead.org, linux-clk@vger.kernel.org,
 devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
 Miquel Raynal <miquel.raynal@bootlin.com>,
 Thomas Petazzoni <thomas.petazzoni@bootlin.com>
References: <20240426-th1520-clk-v2-v2-0-96b829e6fcee@tenstorrent.com>
 <20240426-th1520-clk-v2-v2-4-96b829e6fcee@tenstorrent.com>
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From: Thomas Bonnefille <thomas.bonnefille@bootlin.com>
In-Reply-To: <20240426-th1520-clk-v2-v2-4-96b829e6fcee@tenstorrent.com>
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On 4/27/24 2:10 AM, Drew Fustini wrote:
> Change the clock property in the T-Head TH1520 mmc controller nodes to a
> real clock provided by the AP_SUBSYS clock driver.
> 
> Signed-off-by: Drew Fustini <dfustini@tenstorrent.com>

I experienced that, when the I2C clocks were correctly configured, the 
UART stopped working, likely due to their dependence on FOUTPOSTDIV.
Setting up the UART correctly, for instance:

                 uartx: serial@xxxxxxxxxx {
			...
                         clocks = <&clk CLK_UART_SCLK>, <&clk 
CLK_UARTX_PCLK>;
                         clock-names = "baudclk", "apb_pclk";
                         ...
			status = "disabled";
                 };
resolved the issue.
As this would be mandatory in the future, I suggest that you configure 
all the nodes currently set to a fixed clock, not just the MMC controller.

Thomas