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

[Imran Shaik]

On 8/20/2024 7:36 PM, Andrew Lunn wrote:
> > +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?

These clocks require for DISPCC and CAMCC drivers for register access, 
hence kept enabled at GCC driver probe. The same approach is followed 
for all the targets.

Thanks,
Imran
> 	Andrew