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

[Yongbang Shi <shiyongbang@huawei.com>]

> On Mon, 24 Feb 2025 at 16:03, Yongbang Shi <shiyongbang@huawei.com> wrote:
>>> On Sat, Feb 22, 2025 at 06:35:48PM +0800, Yongbang Shi wrote:
>>>>>> +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.
>>> Why? The link training and mode programming should happen during
>>> pre_enable / enable stage (legacy or atomic).
>> Hi Dmitry,
>>
>> Right, that's what I'm curious about. It won't call encoder enble/disable functions when I triggered HPD.
>> And I'm sure the drm_connector_helper_hpd_irq_event() is called. So I add a drm_client for it.I
> It should be userspace, who triggers the enable/disable (or it should
> be the in-kernel fbdev / fbcon, which interface through the generic
> drm_fbdev client).

Right, I knew it. When I insmode my driver firstly (or restart display service), it will call disable, modeset and enable,
by user, but it won't call when HPD triggered .