With commit 1e4b545, regulator_get will now return -EPROBE_DEFER when the cpu0-supply node is present, but the regulator is not yet registered. It is possible for this to occur when the regulator registration by itself might be defered due to some dependent interface not yet instantiated. For example: an regulator which uses I2C and GPIO might need both systems available before proceeding, in this case, the regulator might defer it's registration. However, the cpufreq-cpu0 driver assumes that any un-successful return result is equivalent of failure. When the regulator_get returns failure other than -EPROBE_DEFER, it makes sense to assume that supply node is not present and proceed with the assumption that only clock control is necessary in the platform. With this change, we can now handle the following conditions: a) cpu0-supply binding is not present, regulator_get will return appropriate error result, resulting in cpufreq-cpu0 driver controlling just the clock. b) cpu0-supply binding is present, regulator_get returns -EPROBE_DEFER, we retry resulting in cpufreq-cpu0 driver registering later once the regulator is available. c) cpu0-supply binding is present, regulator_get returns -EPROBE_DEFER, however, regulator never registers, we retry until cpufreq-cpu0 driver fails to register pointing at device tree information bug. However, in this case, the fact that cpufreq-cpu0 operates with clock only when the DT binding clearly indicates need of a supply is a bug of it's own. d) cpu0-supply gets an regulator at probe - cpufreq-cpu0 driver controls both the clock and regulator Cc: "Rafael J. Wysocki" <rjw@xxxxxxx> Acked-by: Shawn Guo <shawn.guo@xxxxxxxxxx> Signed-off-by: Nishanth Menon <nm@xxxxxx> --- V3: Changes since V1 (for 3.10-rc2?) review comment updates (and dropped Viresh's original ack ;) ). Now that regulator patch https://patchwork.kernel.org/patch/2451211/ has been merged to master based on git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git pm+acpi-3.10-rc1 V2: https://patchwork.kernel.org/patch/2505311/ V1: https://patchwork.kernel.org/patch/2396541/ drivers/cpufreq/cpufreq-cpu0.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c index 3ab8294..ecd8af9 100644 --- a/drivers/cpufreq/cpufreq-cpu0.c +++ b/drivers/cpufreq/cpufreq-cpu0.c @@ -195,6 +195,22 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev) cpu_dev = &pdev->dev; cpu_dev->of_node = np; + cpu_reg = devm_regulator_get(cpu_dev, "cpu0"); + if (IS_ERR(cpu_reg)) { + /* + * If cpu0 regulator supply node is present, but regulator is + * not yet registered, we should try defering probe. + */ + if (PTR_ERR(cpu_reg) == -EPROBE_DEFER) { + dev_err(cpu_dev, "cpu0 regulator not ready, retry\n"); + ret = -EPROBE_DEFER; + goto out_put_node; + } + pr_warn("failed to get cpu0 regulator: %ld\n", + PTR_ERR(cpu_reg)); + cpu_reg = NULL; + } + cpu_clk = devm_clk_get(cpu_dev, NULL); if (IS_ERR(cpu_clk)) { ret = PTR_ERR(cpu_clk); @@ -202,12 +218,6 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev) goto out_put_node; } - cpu_reg = devm_regulator_get(cpu_dev, "cpu0"); - if (IS_ERR(cpu_reg)) { - pr_warn("failed to get cpu0 regulator\n"); - cpu_reg = NULL; - } - ret = of_init_opp_table(cpu_dev); if (ret) { pr_err("failed to init OPP table: %d\n", ret); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
