linux-kernel - Re: [PATCH v6 5/6] drm/i915/gvt: Deliver async primary plane page flip events at vblank

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Message-ID: <20190924141417.7442bcb3@x1.home>
Date:   Tue, 24 Sep 2019 14:14:17 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Tina Zhang <tina.zhang@...el.com>
Cc:     intel-gvt-dev@...ts.freedesktop.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Kechen Lu <kechen.lu@...el.com>,
        kraxel@...hat.com, zhenyuw@...ux.intel.com, zhiyuan.lv@...el.com,
        zhi.a.wang@...el.com, kevin.tian@...el.com, hang.yuan@...el.com,
        yi.l.liu@...el.com
Subject: Re: [PATCH v6 5/6] drm/i915/gvt: Deliver async primary plane page
 flip events at vblank

On Tue, 24 Sep 2019 14:41:42 +0800
Tina Zhang <tina.zhang@...el.com> wrote:

> From: Kechen Lu <kechen.lu@...el.com>
> 
> Only sync primary plane page flip events are checked and delivered
> as the display refresh events before, this patch tries to deliver async
> primary page flip events bounded by vblanks.
> 
> To deliver correct async page flip, the new async flip bitmap is
> introduced and in vblank emulation handler to check bitset.
> 
> Signed-off-by: Kechen Lu <kechen.lu@...el.com>
> Signed-off-by: Tina Zhang <tina.zhang@...el.com>
> ---
>  drivers/gpu/drm/i915/gvt/cmd_parser.c |  6 ++++--
>  drivers/gpu/drm/i915/gvt/display.c    | 10 ++++++++++
>  drivers/gpu/drm/i915/gvt/gvt.h        |  2 ++
>  drivers/gpu/drm/i915/gvt/handlers.c   |  5 +++--
>  4 files changed, 19 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/cmd_parser.c b/drivers/gpu/drm/i915/gvt/cmd_parser.c
> index e753b1e706e2..1abb05431177 100644
> --- a/drivers/gpu/drm/i915/gvt/cmd_parser.c
> +++ b/drivers/gpu/drm/i915/gvt/cmd_parser.c
> @@ -1365,9 +1365,11 @@ static int gen8_update_plane_mmio_from_mi_display_flip(
>  	if (info->plane == PLANE_PRIMARY)
>  		vgpu_vreg_t(vgpu, PIPE_FLIPCOUNT_G4X(info->pipe))++;
>  
> -	if (info->async_flip)
> +	if (info->async_flip) {
>  		intel_vgpu_trigger_virtual_event(vgpu, info->event);
> -	else
> +		set_bit(info->plane,
> +			vgpu->display.async_flip_event[info->pipe]);
> +	} else
>  		set_bit(info->event, vgpu->irq.flip_done_event[info->pipe]);
>  
>  	return 0;
> diff --git a/drivers/gpu/drm/i915/gvt/display.c b/drivers/gpu/drm/i915/gvt/display.c
> index 9f2c2cd10369..9acde0bdd5f4 100644
> --- a/drivers/gpu/drm/i915/gvt/display.c
> +++ b/drivers/gpu/drm/i915/gvt/display.c
> @@ -419,6 +419,16 @@ static void emulate_vblank_on_pipe(struct intel_vgpu *vgpu, int pipe)
>  		intel_vgpu_trigger_virtual_event(vgpu, event);
>  	}
>  
> +	for_each_set_bit(event, vgpu->display.async_flip_event[pipe],
> +			I915_MAX_PLANES) {
> +		clear_bit(event, vgpu->display.async_flip_event[pipe]);
> +		if (!pipe_is_enabled(vgpu, pipe))
> +			continue;
> +
> +		if (event == PLANE_PRIMARY)
> +			eventfd_signal_val |= DISPLAY_PRI_REFRESH_EVENT_VAL;

Is it worthwhile to continue the for_each_set_bit here, or should we
clear the remaining bits and break from the loop?  Thanks,

Alex

> +	}
> +
>  	if (eventfd_signal_val)
>  		vgpu->no_pageflip_count = 0;
>  	else if (!eventfd_signal_val && vgpu->no_pageflip_count > PAGEFLIP_DELAY_THR)
> diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
> index cc39b449b061..73769a87b407 100644
> --- a/drivers/gpu/drm/i915/gvt/gvt.h
> +++ b/drivers/gpu/drm/i915/gvt/gvt.h
> @@ -128,6 +128,8 @@ struct intel_vgpu_display {
>  	struct intel_vgpu_i2c_edid i2c_edid;
>  	struct intel_vgpu_port ports[I915_MAX_PORTS];
>  	struct intel_vgpu_sbi sbi;
> +	DECLARE_BITMAP(async_flip_event[I915_MAX_PIPES],
> +		       I915_MAX_PLANES);
>  };
>  
>  struct vgpu_sched_ctl {
> diff --git a/drivers/gpu/drm/i915/gvt/handlers.c b/drivers/gpu/drm/i915/gvt/handlers.c
> index 45a9124e53b6..e5a022c2e7bb 100644
> --- a/drivers/gpu/drm/i915/gvt/handlers.c
> +++ b/drivers/gpu/drm/i915/gvt/handlers.c
> @@ -760,9 +760,10 @@ static int pri_surf_mmio_write(struct intel_vgpu *vgpu, unsigned int offset,
>  
>  	vgpu_vreg_t(vgpu, PIPE_FLIPCOUNT_G4X(pipe))++;
>  
> -	if (vgpu_vreg_t(vgpu, DSPCNTR(pipe)) & PLANE_CTL_ASYNC_FLIP)
> +	if (vgpu_vreg_t(vgpu, DSPCNTR(pipe)) & PLANE_CTL_ASYNC_FLIP) {
>  		intel_vgpu_trigger_virtual_event(vgpu, event);
> -	else
> +		set_bit(PLANE_PRIMARY, vgpu->display.async_flip_event[pipe]);
> +	} else
>  		set_bit(event, vgpu->irq.flip_done_event[pipe]);
>  
>  	return 0;