Message-ID: <3465ce51-a844-4c77-8e80-179d5ca279cc@huawei.com>
Date: Wed, 5 Mar 2025 15:29:19 +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


> On Tue, Mar 04, 2025 at 10:23:14AM +0800, Yongbang Shi wrote:
>>> On Mon, Mar 03, 2025 at 01:02:44PM +0800, Yongbang Shi wrote:
>>>>> On Sat, 1 Mar 2025 at 11:54, Yongbang Shi <shiyongbang@...wei.com> wrote:
>>>>>>> On Sat, Mar 01, 2025 at 04:45:40PM +0800, Yongbang Shi wrote:
>>>>>>>>> On Thu, Feb 27, 2025 at 09:46:10PM +0800, Yongbang Shi wrote:
>>>>>>>>>>> On Tue, Feb 25, 2025 at 09:57:17PM +0800, Yongbang Shi wrote:
>>>>>>>>>>>>> On Mon, 24 Feb 2025 at 16:03, Yongbang Shi <shiyongbang@...wei.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 .
>>>>>>>>>>> - Is HPD even properly delivered to userspace? What kind of compsitor
>>>>>>>>>>>         are you using? Is .detect working properly and reporting a correct
>>>>>>>>>>>         plug-in state?
>>>>>>>>>> Thanks for your answering. I'm not very good understanding about userspace in framework. In my opinion, when I call
>>>>>>>>>> this drm_connector_helper_hpd_irq_event(), the HPD will deliver to userspace.
>>>>>>>>>> I use Xorg, and the display service is GDM.
>>>>>>>>>> The .detect is called and the getting modes info is correct.
>>>>>>>>>> I find that it would only trigger(disable, modeset and enable), when I changed resolutions, restart display service and insmod driver.
>>>>>>>>> You can go to the display settings in GDM. It would be interesting to
>>>>>>>>> observe if it notes the second monitor or not. Last, but not least, you
>>>>>>>>> can use a simple tool like 'xrandr' under your XOrg session to set the
>>>>>>>>> display resolution.
>>>>>>>> Thank you for your advice!
>>>>>>>> Right, there are DP and VGA two monitors. I tried to totally remove the vga connector in driver, the problem is gone.
>>>>>>>> So do I need to clear the vga connector, if dp is plugged in?
>>>>>>> Unless your hardware can not manage two outputs at the same time, no,
>>>>>>> you don't have to. Just check how it behaves on x86 systems. Ideally
>>>>>>> your driver should have the same behaviour.
>>>>>> Our hardware cannot support two outputs with different timing, so I used the one crtc and one plane that DP and VGA share. And just add a new DP connector
>>>>>> with a encoder, just like the previous VGA's code logic. But the HPD problem makes me feel confused, should I change the framwork structure to slove this problem?
>>>>> I think registering a single CRTC is a correct way. Then it is logical
>>>>> that there is no mode set on the DP when you connect it. The userspace
>>>>> can not output any data. However if you disconnect VGA and connect DP
>>>>> then it should become active and should output your desktop
>>>>> environment.
>>>> Okay, Thank you for your guidance. So I need to disconnect VGA when I get the HPD (plugged in) , then
>>>> userapce will active and enanble DP, right?
>>> Yes.
>> I'm sorry for that, just wanna make sure one more thing. I found if I only set the VGA connector's status to disconnected when HPD plugged in, it won't be active.
> Huh? You should implement hibmc_connector_funcs.detect() or
> .detect_ctx() to report VGA connector's status. Use
> ast_vga_connector_helper_detect_ctx() as an inspiration.

Okay, thanks for your correcting, I'll try to add drm_connector_helper_detect_from_ddc() in VGA's detect_ctx.
And also, I wanna make sure that do I need to unplug the VGA monitor manually when I plug in DP, or just
set the status of VGA connector to disconnected in interrupt handler.


>> And If I add drm_cleanup_connector() for VGA, it work. So is this okay that I use this cleanup in HPD?
> drm_connector_cleanup() should only be callsed if the connector is going
> to be destroyed. You should not be callign that function.
>
>>
>>>>>> And also, I will check whether this driver works good on the x86 server. Right now, I'm testing on arm64 server.
>>>>>>
>>>>>>>> And also, I used xrandr to set modes after 'startx'. Changing resolutions works,
>>>>>>>> but there are errs when set some low resolutions.
>>>>>>> That's a separate topic, most likely related to timing or to some other
>>>>>>> issues. You can fix that separately (but please do, switching modes
>>>>>>> should work).
>>>>>> Okay!
>>>>>>
>>>>>>

Powered by blists - more mailing lists