Re: [PATCH 4/5] clk: qcom: Add camera clock controller driver for SM8150

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On 29/02/2024 5:38 a.m., Satya Priya Kakitapalli wrote:
Add support for the camera clock controller for camera clients
to be able to request for camcc clocks on SM8150 platform.

Signed-off-by: Satya Priya Kakitapalli <quic_skakitap@xxxxxxxxxxx>
---

+static int cam_cc_sm8150_probe(struct platform_device *pdev)
+{
+	struct regmap *regmap;
+	int ret;
+
+	ret = devm_pm_runtime_enable(&pdev->dev);
+	if (ret)
+		return ret;
+
+	ret = pm_runtime_resume_and_get(&pdev->dev);
+	if (ret)
+		return ret;
+
+	regmap = qcom_cc_map(pdev, &cam_cc_sm8150_desc);
+	if (IS_ERR(regmap)) {
+		pm_runtime_put(&pdev->dev);
+		return PTR_ERR(regmap);
+	}
+
+	clk_trion_pll_configure(&cam_cc_pll0, regmap, &cam_cc_pll0_config);
+	clk_trion_pll_configure(&cam_cc_pll1, regmap, &cam_cc_pll1_config);
+	clk_regera_pll_configure(&cam_cc_pll2, regmap, &cam_cc_pll2_config);
+	clk_trion_pll_configure(&cam_cc_pll3, regmap, &cam_cc_pll3_config);
+	clk_trion_pll_configure(&cam_cc_pll4, regmap, &cam_cc_pll4_config);
+
+	/* Keep the critical clock always-on */
+	qcom_branch_set_clk_en(regmap, 0xc1e4); /* cam_cc_gdsc_clk */

Does this clock need to be specified this way ?

drivers/clk/qcom/camcc-sc8280xp.c::camcc_gdsc_clk specifies the gdsc clock as a shared op clock.

Actually it looks to be register compatible, please try defining titan_top_gdsc as per the example in 8280xp.

+
+	ret = qcom_cc_really_probe(pdev, &cam_cc_sm8150_desc, regmap);
+
+	pm_runtime_put(&pdev->dev);
+
+	return ret;
+}

So this is a pattern we keep repeating in the clock probe() functions which I am writing a series to address. There's no need to continue to replicate the bug in new code though.

Only switch on always-on clocks if probe succeeds.

	ret = qcom_cc_really_probe(pdev, &cam_cc_sm8150_desc, regmap);
	if (ret)
		goto probe_err;

	qcom_branch_set_clk_en(regmap, 0xc1e4); /* cam_cc_gdsc_clk */

	pm_runtime_put(&pdev->dev);

	return 0;

probe_err:
	pm_runtime_put_sync(&pdev->dev);

Alternatively switch on the always-on clocks before the really_probe() but then roll back in a probe_err: goto

probe_err:
	remap_bits_update(regmap, 0xc1e4, BIT(0), 0);
	pm_runtime_put_sync(&pdev->dev);

There may be corner cases where always-on has to happen before really_probe() I suppose but as a general pattern the above should be how we go.

Anyway I suspect the right thing to do is to define a titan_top_gdsc_clk with shared ops to "park" the GDSC clock to 19.2 MHz instead of turning it off.

You can get rid of the hard-coded always-on and indeed represent the clock in /sysfs - which is preferable IMO to just whacking registers to keep clocks always-on in probe anyway.

Please try to define the titan_top_gdsc_clk as a shared_ops clock instead of hard coding to always on.

If that doesn't work for some reason, then please fix your always-on logic in probe() to only make the clock fixed on, if really_probe() succeeds.

---
bod




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