Re: [PATCH v2 5/5] clk: qcom: ipq4019: Added the cpu clock frequency change notifier
From: Stephen Boyd <hidden>
Date: 2016-08-15 22:26:18
Also in:
linux-arm-msm, linux-clk, lkml
On 06/21, Abhishek Sahu wrote:
quoted hunk ↗ jump to hunk
The current driver code gives the crash or gets hang while switching the CPU frequency some time. The APSS CPU Clock divider is not glitch free so it the APPS clock need to be switched for stable clock during the change. This patch adds the frequency change notifier for APSS CPU clock. It changes the parent of this clock to stable PLL FEPLL500 when it gets for PRE_RATE_CHANGE event. This event will be generated before actual clock set operations. The clock set operation will again change its corresponding parent by getting the same from frequency table. Signed-off-by: Abhishek Sahu <redacted> --- drivers/clk/qcom/gcc-ipq4019.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)diff --git a/drivers/clk/qcom/gcc-ipq4019.c b/drivers/clk/qcom/gcc-ipq4019.c index df159c2..3c014f7 100644 --- a/drivers/clk/qcom/gcc-ipq4019.c +++ b/drivers/clk/qcom/gcc-ipq4019.c@@ -1740,9 +1740,34 @@ static const struct of_device_id gcc_ipq4019_match_table[] = { }; MODULE_DEVICE_TABLE(of, gcc_ipq4019_match_table); +int cpu_clk_notifier_fn(struct notifier_block *nb,
static? Please come up with a better name that is not so generic.
+ unsigned long action, void *data)
+{
+ int err = 0;
+
+ if (action == PRE_RATE_CHANGE) {
+ err = clk_rcg2_ops.set_parent(&apps_clk_src.clkr.hw,
+ P_FEPLL500);
+ }
+
+ return notifier_from_errno(err);
+}
+
+struct notifier_block cpu_clk_notifier = {static?
+ .notifier_call = cpu_clk_notifier_fn,
+};
+
static int gcc_ipq4019_probe(struct platform_device *pdev)
{
- return qcom_cc_probe(pdev, &gcc_ipq4019_desc);
+ int err;
+
+ err = qcom_cc_probe(pdev, &gcc_ipq4019_desc);
+
+ if (!err)
+ clk_notifier_register(apps_clk_src.clkr.hw.clk,
+ &cpu_clk_notifier);This has to be unregistered on driver remove.
+ + return err; }
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