linux-kernel - Re: [PATCH] drm: bridge: dw_hdmi: Add cec suspend/resume functions

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Message-ID: <d27c41a1-d50f-c346-d559-ab367383fc51@linaro.org>
Date:   Tue, 1 Aug 2023 11:36:36 +0200
From:   neil.armstrong@...aro.org
To:     Sandor Yu <Sandor.yu@....com>, andrzej.hajda@...el.com,
        rfoss@...nel.org, Laurent.pinchart@...asonboard.com,
        jonas@...boo.se, jernej.skrabec@...il.com, airlied@...il.com,
        daniel@...ll.ch, u.kleine-koenig@...gutronix.de,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm: bridge: dw_hdmi: Add cec suspend/resume functions

On 21/07/2023 14:44, 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@....com>
> ---
>   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 9389ce526eb13..be21c11de1f2a 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)
> @@ -304,11 +308,44 @@ static void dw_hdmi_cec_remove(struct platform_device *pdev)
>   	cec_unregister_adapter(cec->adap);
>   }
>   
> +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 registers */
> +	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 registers */
> +	 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_new = dw_hdmi_cec_remove,
>   	.driver = {
>   		.name = "dw-hdmi-cec",
> +		.pm = &dw_hdmi_cec_pm,
>   	},
>   };
>   module_platform_driver(dw_hdmi_cec_driver);

Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>