linux-kernel - Re: [PATCH 1/2] drm: introduce page_flip

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Message-ID: <1a75a4d2-64f3-4d19-802c-fc5c79b002c6@amd.com>
Date: Thu, 29 Jan 2026 15:24:56 +0100
From: Christian König <christian.koenig@....com>
To: Hamza Mahfooz <someguy@...ective-light.com>
Cc: Timur Kristóf <timur.kristof@...il.com>,
 Alex Deucher <alexdeucher@...il.com>,
 Michel Dänzer <michel.daenzer@...lbox.org>,
 Mario Limonciello <mario.limonciello@....com>,
 dri-devel@...ts.freedesktop.org, Alex Deucher <alexander.deucher@....com>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Harry Wentland <harry.wentland@....com>, Leo Li <sunpeng.li@....com>,
 Rodrigo Siqueira <siqueira@...lia.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Sunil Khatri <sunil.khatri@....com>, Ce Sun <cesun102@....com>,
 Lijo Lazar <lijo.lazar@....com>, Kenneth Feng <kenneth.feng@....com>,
 Ivan Lipski <ivan.lipski@....com>, Alex Hung <alex.hung@....com>,
 Tom Chung <chiahsuan.chung@....com>, Melissa Wen <mwen@...lia.com>,
 Fangzhi Zuo <Jerry.Zuo@....com>, amd-gfx@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] drm: introduce page_flip_timeout()

On 1/29/26 15:04, Hamza Mahfooz wrote:
> On Thu, Jan 29, 2026 at 01:59:00PM +0100, Christian König wrote:
>>> How do you propose to do that?
>>
>> I need to dig a bit into the DAL/DC code and see how the signaling path actually goes.
>>
>> Going to give that a try tomorrow.
>>
> 
> For recent ASICs, something along the lines of the following should do
> the trick:

Thanks a lot for that. What happens if you apply this?

Can the higher level handling recover from that? E.g. continue after 10 second timeout.

Thanks,
Christian.

> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
> index dc8d2f52c7d6..fac668c2fcfb 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
> @@ -510,6 +510,7 @@ struct amdgpu_crtc {
>  	bool wb_pending;
>  	bool wb_enabled;
>  	struct drm_writeback_connector *wb_conn;
> +	int pflip_cnt;
>  };
>  
>  struct amdgpu_encoder_atom_dig {
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 740711ac1037..1c3b7fbab1c6 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -427,6 +427,18 @@ static inline bool update_planes_and_stream_adapter(struct dc *dc,
>  					   stream_update);
>  }
>  
> +static inline bool update_pflip_cnt(struct amdgpu_crtc *acrtc)
> +{
> +	int cnt = acrtc->pflip_cnt++;
> +
> +	if (cnt == 300) {
> +		acrtc->pflip_cnt = 0;
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
>  /**
>   * dm_pflip_high_irq() - Handle pageflip interrupt
>   * @interrupt_params: ignored
> @@ -454,6 +466,9 @@ static void dm_pflip_high_irq(void *interrupt_params)
>  		return;
>  	}
>  
> +	if (update_pflip_cnt(amdgpu_crtc))
> +		return;
> +
>  	spin_lock_irqsave(&adev_to_drm(adev)->event_lock, flags);
>  
>  	if (amdgpu_crtc->pflip_status != AMDGPU_FLIP_SUBMITTED) {
> @@ -589,6 +604,9 @@ static void dm_vupdate_high_irq(void *interrupt_params)
>  	acrtc = get_crtc_by_otg_inst(adev, irq_params->irq_src - IRQ_TYPE_VUPDATE);
>  
>  	if (acrtc) {
> +		if (update_pflip_cnt(acrtc))
> +			return;
> +
>  		vrr_active = amdgpu_dm_crtc_vrr_active_irq(acrtc);
>  		drm_dev = acrtc->base.dev;
>  		vblank = drm_crtc_vblank_crtc(&acrtc->base);
> @@ -659,6 +677,9 @@ static void dm_crtc_high_irq(void *interrupt_params)
>  	if (!acrtc)
>  		return;
>  
> +	if (update_pflip_cnt(acrtc))
> +		return;
> +
>  	if (acrtc->wb_conn) {
>  		spin_lock_irqsave(&acrtc->wb_conn->job_lock, flags);