On Sat, Sep 7, 2019 at 9:22 PM Stephen Boyd [off-list ref] wrote:

Quoting Dong Aisheng (2019-08-20 04:13:25)

quoted

diff --git a/drivers/clk/imx/clk-lpcg-scu.c b/drivers/clk/imx/clk-lpcg-scu.c
index 3c092a0..4df0818 100644
--- a/drivers/clk/imx/clk-lpcg-scu.c
+++ b/drivers/clk/imx/clk-lpcg-scu.c

@@ -33,6 +33,9 @@ struct clk_lpcg_scu {
        void __iomem *reg;
        u8 bit_idx;
        bool hw_gate;
+
+       /* for state save&restore */
+       u32 state;
 };

 #define to_clk_lpcg_scu(_hw) container_of(_hw, struct clk_lpcg_scu, hw)

@@ -112,5 +115,35 @@ struct clk_hw *__imx_clk_lpcg_scu(struct device *dev, const char *name,
                hw = ERR_PTR(ret);
        }

+       if (dev)
+               dev_set_drvdata(dev, clk);
+
        return hw;
 }
+
+int __maybe_unused imx_clk_lpcg_scu_suspend(struct device *dev)

static?

quoted

+{
+       struct clk_lpcg_scu *clk = dev_get_drvdata(dev);
+
+       clk->state = readl_relaxed(clk->reg);
+       dev_dbg(dev, "save lpcg state 0x%x\n", clk->state);
+
+       return 0;
+}
+
+int __maybe_unused imx_clk_lpcg_scu_resume(struct device *dev)

static?

Will fix.

quoted

+{
+       struct clk_lpcg_scu *clk = dev_get_drvdata(dev);
+
+       /* FIXME: double write in case a failure */

What does this mean? Sometimes writes don't work unless the CPU issues
them twice?

Yes, it's a hardware timing issues.

Regards
Aisheng

quoted

+       writel(clk->state, clk->reg);
+       writel(clk->state, clk->reg);
+       dev_dbg(dev, "restore lpcg state 0x%x\n", clk->state);
+
+       return 0;
+}
+
+const struct dev_pm_ops imx_clk_lpcg_scu_pm_ops = {
+       SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx_clk_lpcg_scu_suspend,
+                                     imx_clk_lpcg_scu_resume)
+};

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