linux-kernel - Re: [PATCH v3 drm-dp 7/8] drm/hisilicon/hibmc: Enable this hot plug detect of irq feature

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Message-ID: <eef68fc7-30f4-4246-a82e-4f90cd6a665d@huawei.com>
Date: Sat, 22 Feb 2025 18:35:48 +0800
From: Yongbang Shi <shiyongbang@...wei.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: <xinliang.liu@...aro.org>, <tiantao6@...ilicon.com>,
	<maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
	<tzimmermann@...e.de>, <airlied@...il.com>, <daniel@...ll.ch>,
	<kong.kongxinwei@...ilicon.com>, <liangjian010@...wei.com>,
	<chenjianmin@...wei.com>, <lidongming5@...wei.com>, <libaihan@...wei.com>,
	<shenjian15@...wei.com>, <shaojijie@...wei.com>,
	<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
	<shiyongbang@...wei.com>
Subject: Re: [PATCH v3 drm-dp 7/8] drm/hisilicon/hibmc: Enable this hot plug
 detect of irq feature

>> +static int hibmc_dp_hpd_event(struct drm_client_dev *client)
>> +{
>> +	struct hibmc_dp *dp = container_of(client, struct hibmc_dp, client);
>> +	struct hibmc_drm_private *priv = to_hibmc_drm_private(dp->drm_dev);
>> +	struct drm_display_mode *mode = &priv->crtc.state->adjusted_mode;
>> +	int ret;
>> +
>> +	if (dp->hpd_status) {
>> +		hibmc_dp_hpd_cfg(&priv->dp);
>> +		ret = hibmc_dp_prepare(dp, mode);
>> +		if (ret)
>> +			return ret;
>> +
>> +		hibmc_dp_display_en(dp, true);
>> +	} else {
>> +		hibmc_dp_display_en(dp, false);
>> +		hibmc_dp_reset_link(&priv->dp);
>> +	}
> If I understand this correctly, you are using a separate drm_client to
> enable and disable the link & display. Why is it necessary? Existing
> drm_clients and userspace compositors use drm framework, they should be
> able to turn the display on and off as required.
>
Thanks for your asking, there are cfg/reset process when the connector 's pluging in/out.
We want to cfg DP registers again when the connector changes. Not only dp link training, but also cfg
the different video modes into DP registers.


>> +
>> +	return 0;
>> +}
>> +
>> +static const struct drm_client_funcs hibmc_dp_client_funcs = {
>> +	.hotplug = hibmc_dp_hpd_event,
>> +	.unregister = drm_client_release,
>> +};
>> +
>>   int hibmc_dp_init(struct hibmc_drm_private *priv)
>>   {
>>   	struct drm_device *dev = &priv->dev;
>> @@ -138,5 +193,11 @@ int hibmc_dp_init(struct hibmc_drm_private *priv)
>>   
>>   	drm_connector_attach_encoder(connector, encoder);
>>   
>> +	ret = drm_client_init(dev, &dp->client, "hibmc-DP-HPD", &hibmc_dp_client_funcs);
>> +	if (ret)
>> +		return ret;
>> +
>> +	drm_client_register(&dp->client);
>> +
>>   	return 0;
>>   }
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
>> index bc89e4b9f4e3..daed1330b961 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
>> @@ -71,4 +71,6 @@ int hibmc_dp_init(struct hibmc_drm_private *priv);
>>   
>>   void hibmc_debugfs_init(struct drm_connector *connector, struct dentry *root);
>>   
>> +irqreturn_t hibmc_dp_hpd_isr(int irq, void *arg);
>> +
>>   #endif
>> -- 
>> 2.33.0
>>