Re: [PATCH v2 2/2] clk: qcom: Add support for Global Clock Controller on QCS8300

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On 8/26/2024 6:24 PM, Andrew Lunn wrote:
On Mon, Aug 26, 2024 at 04:25:39PM +0530, Imran Shaik wrote:


On 8/23/2024 1:29 AM, 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 */

Sorry, but you need to explain why. Why cannot the camera driver
enable these clocks when it loads? Why cannot the display driver
enable these clocks when it loads.


These clocks are recommended to be kept always ON as per the HW design and
also exposing clock structures and marking them critical in the kernel would
lead to redundant code. Based on previous discussions with clock
maintainers, it is recommended to keep such clocks enabled at probe and not
model them. This approach is consistently followed for all other targets as
well.

I don't see why it would add redundant code. It is a few lines of code
in the driver, which every driver using clocks has. If you really
don't want the clock turned off because it is unused, you can use
CLK_IGNORE_UNUSED, along with a comment explaining why.

What i was actually guessing is that you don't actually have open
drivers for these hardware blocks, just a blob running in user
space. As such, it cannot turn the clocks on. If that is the case, i
would much prefer you are honest about this, and document it.


We have recently discussed enabling the clocks at probe with the maintainers in the below threads as well.

https://lore.kernel.org/all/664cca91-8615-d3f6-7525-15b9b6725cce@xxxxxxxxxxx/

It was concluded that keeping them enabled at probe is acceptable. We are now following this approach across all targets.

Thanks,
Imran

	Andrew




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