linux-kernel - Re: [PATCH 2/2] clk: qcom: Add support for Global Clock Controller on QCS8300

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Message-ID: <a7afdd6d-47a1-41c7-8a0d-27919cf5af90@lunn.ch>
Date: Tue, 20 Aug 2024 16:06:03 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Imran Shaik <quic_imrashai@...cinc.com>
Cc: Bjorn Andersson <andersson@...nel.org>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Richard Cochran <richardcochran@...il.com>,
	Ajit Pandey <quic_ajipan@...cinc.com>,
	Taniya Das <quic_tdas@...cinc.com>,
	Jagadeesh Kona <quic_jkona@...cinc.com>,
	Satya Priya Kakitapalli <quic_skakitap@...cinc.com>,
	linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org
Subject: Re: [PATCH 2/2] clk: qcom: Add support for Global Clock Controller
 on QCS8300

> +static int gcc_qcs8300_probe(struct platform_device *pdev)
> +{
> +	struct regmap *regmap;
> +	int ret;
> +
> +	regmap = qcom_cc_map(pdev, &gcc_qcs8300_desc);
> +	if (IS_ERR(regmap))
> +		return PTR_ERR(regmap);
> +
> +	ret = qcom_cc_register_rcg_dfs(regmap, gcc_dfs_clocks,
> +				       ARRAY_SIZE(gcc_dfs_clocks));
> +	if (ret)
> +		return ret;
> +
> +	/* Keep some clocks always enabled */
> +	qcom_branch_set_clk_en(regmap, 0x32004); /* GCC_CAMERA_AHB_CLK */
> +	qcom_branch_set_clk_en(regmap, 0x32020); /* GCC_CAMERA_XO_CLK */

It would be good to document why. Why does the camera driver not
enable the clock when it loads?

> +	qcom_branch_set_clk_en(regmap, 0x33004); /* GCC_DISP_AHB_CLK */
> +	qcom_branch_set_clk_en(regmap, 0x33018); /* GCC_DISP_XO_CLK */
> +	qcom_branch_set_clk_en(regmap, 0x7d004); /* GCC_GPU_CFG_AHB_CLK */
> +	qcom_branch_set_clk_en(regmap, 0x34004); /* GCC_VIDEO_AHB_CLK */
> +	qcom_branch_set_clk_en(regmap, 0x34024); /* GCC_VIDEO_XO_CLK */

Why cannot the display driver enable the clock when it loads?

	Andrew