linux-kernel - Re: [PATCHv6 3/4] drm/omap: add framedone interrupt support

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Date:   Tue, 28 May 2019 13:19:01 +0300
From:   Tomi Valkeinen <tomi.valkeinen@...com>
To:     Sebastian Reichel <sebastian.reichel@...labora.com>,
        Sebastian Reichel <sre@...nel.org>,
        Tony Lindgren <tony@...mide.com>, Pavel Machek <pavel@....cz>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
CC:     "H. Nikolaus Schaller" <hns@...delico.com>,
        <dri-devel@...ts.freedesktop.org>, <linux-omap@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <kernel@...labora.com>
Subject: Re: [PATCHv6 3/4] drm/omap: add framedone interrupt support

Hi Sebastian,

On 23/05/2019 23:07, Sebastian Reichel wrote:

> @@ -302,6 +328,30 @@ void omap_crtc_vblank_irq(struct drm_crtc *crtc)
>   	DBG("%s: apply done", omap_crtc->name);
>   }
>   
> +void omap_crtc_framedone_irq(struct drm_crtc *crtc, uint32_t irqstatus)
> +{
> +	struct omap_crtc *omap_crtc = to_omap_crtc(crtc);
> +
> +	if (!omap_crtc->framedone_handler) {
> +		dev_warn(omap_crtc->base.dev->dev, "no framedone handler?");
> +		return;
> +	}

This triggers on normal displays.

FRAMEDONE is an interrupt we get when DISPC's output videoport is being 
turned off. It's raised after the last frame has been finished (i.e. the 
DISPC is truly done with that videoport).

We get it for both conventional displays (when the display is turned 
off) and for DSI command mode (when a single frame has been sent), as in 
both cases the videoport is disabled after the operation. For 
conventional displays, you can think FRAMEDONE as the last vsync.

We also have special handling for FRAMEDONE in omap_crtc_set_enabled(), 
which is used to get the drm driver to wait for FRAMEDONE when disabling 
the display. I wonder if this separate framedone handling might somehow 
conflict with that code. And/or should these be somehow combined.

  Tomi

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