Seems that, in order to be able to resume from suspend, the dram rate
needs to be the highest one available. Therefore, add the late system
suspend/resume PM ops which set the highest rate on suspend and the
latest one used before suspending on resume.

Signed-off-by: Abel Vesa <redacted>
---
  drivers/devfreq/imx8m-ddrc.c | 26 ++++++++++++++++++++++++++
  1 file changed, 26 insertions(+)

diff --git a/drivers/devfreq/imx8m-ddrc.c b/drivers/devfreq/imx8m-ddrc.c
index 33de83acfd8b..04347dee781b 100644
--- a/drivers/devfreq/imx8m-ddrc.c
+++ b/drivers/devfreq/imx8m-ddrc.c

@@ -72,6 +72,8 @@ struct imx8m_ddrc {
  	struct clk *dram_alt;
  	struct clk *dram_apb;
  
+	unsigned long suspend_rate;
+	unsigned long resume_rate;
  	int freq_count;
  	struct imx8m_ddrc_freq freq_table[IMX8M_DDRC_MAX_FREQ_COUNT];
  };

@@ -271,6 +273,22 @@ static int imx8m_ddrc_target(struct device *dev, unsigned long *freq, u32 flags)
  	return ret;
  }
  
+static int imx8m_ddrc_suspend(struct device *dev)
+{
+	struct imx8m_ddrc *priv = dev_get_drvdata(dev);
+
+	priv->resume_rate = clk_get_rate(priv->dram_core);
+
+	return imx8m_ddrc_target(dev, &priv->suspend_rate, 0);
+}
+
+static int imx8m_ddrc_resume(struct device *dev)
+{
+	struct imx8m_ddrc *priv = dev_get_drvdata(dev);
+
+	return imx8m_ddrc_target(dev, &priv->resume_rate, 0);
+}
+
  static int imx8m_ddrc_get_cur_freq(struct device *dev, unsigned long *freq)
  {
  	struct imx8m_ddrc *priv = dev_get_drvdata(dev);

@@ -336,6 +354,9 @@ static int imx8m_ddrc_init_freq_info(struct device *dev)
  
  		if (dev_pm_opp_add(dev, freq->rate * 250000, 0))
  			return -ENODEV;
+
+		if (index ==  0)
+			priv->suspend_rate = freq->rate * 250000;
  	}
  
  	return 0;

@@ -412,10 +433,15 @@ static const struct of_device_id imx8m_ddrc_of_match[] = {
  };
  MODULE_DEVICE_TABLE(of, imx8m_ddrc_of_match);
  
+static const struct dev_pm_ops imx8m_ddrc_pm_ops = {
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(imx8m_ddrc_suspend, imx8m_ddrc_resume)
+};