Re: [PATCH v2 1/5] drm: bridge: dw_hdmi: cec: Add cec suspend/resume function

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On 08/04/2022 12:32, Sandor Yu wrote:
CEC interrupt status/mask and logical address registers
will be reset when device enter suspend.
It will cause cec fail to work after device resume.
Add CEC suspend/resume functions, reinitialize logical address registers
and restore interrupt status/mask registers after resume.

Signed-off-by: Sandor Yu <Sandor.yu@xxxxxxx>
---
  drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c | 37 +++++++++++++++++++
  1 file changed, 37 insertions(+)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c
index c8f44bcb298a..ab176401b727 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c
@@ -62,6 +62,10 @@ struct dw_hdmi_cec {
  	bool rx_done;
  	struct cec_notifier *notify;
  	int irq;
+
+	u8 regs_polarity;
+	u8 regs_mask;
+	u8 regs_mute_stat0;
  };
static void dw_hdmi_write(struct dw_hdmi_cec *cec, u8 val, int offset)
@@ -306,11 +310,44 @@ static int dw_hdmi_cec_remove(struct platform_device *pdev)
  	return 0;
  }
+static int __maybe_unused dw_hdmi_cec_resume(struct device *dev)
+{
+	struct dw_hdmi_cec *cec = dev_get_drvdata(dev);
+
+	/* Restore logical address */
+	dw_hdmi_write(cec, cec->addresses & 255, HDMI_CEC_ADDR_L);
+	dw_hdmi_write(cec, cec->addresses >> 8, HDMI_CEC_ADDR_H);
+
+	/* Restore interrupt status/mask register */
+	dw_hdmi_write(cec, cec->regs_polarity, HDMI_CEC_POLARITY);
+	dw_hdmi_write(cec, cec->regs_mask, HDMI_CEC_MASK);
+	dw_hdmi_write(cec, cec->regs_mute_stat0, HDMI_IH_MUTE_CEC_STAT0);
+
+	return 0;
+}
+
+static int __maybe_unused dw_hdmi_cec_suspend(struct device *dev)
+{
+	struct dw_hdmi_cec *cec = dev_get_drvdata(dev);
+
+	/* store interrupt status/mask register */
+	 cec->regs_polarity = dw_hdmi_read(cec, HDMI_CEC_POLARITY);
+	 cec->regs_mask = dw_hdmi_read(cec, HDMI_CEC_MASK);
+	 cec->regs_mute_stat0 = dw_hdmi_read(cec, HDMI_IH_MUTE_CEC_STAT0);
+
+	return 0;
+}
+
+static const struct dev_pm_ops dw_hdmi_cec_pm = {
+	SET_SYSTEM_SLEEP_PM_OPS(dw_hdmi_cec_suspend, dw_hdmi_cec_resume)
+};
+
  static struct platform_driver dw_hdmi_cec_driver = {
  	.probe	= dw_hdmi_cec_probe,
  	.remove	= dw_hdmi_cec_remove,
  	.driver = {
  		.name = "dw-hdmi-cec",
+		.pm = &dw_hdmi_cec_pm,
  	},
  };
  module_platform_driver(dw_hdmi_cec_driver);

As Hans said on v1, why don't you call dw_hdmi_cec_enable(cec->adap, false) in suspend and dw_hdmi_cec_enable(cec->adap, true) in resume ?

With this, CEC engine is not disabled on suspend.

Do you plan to use the engine from the suspend code ?

Neil



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