From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH v2 4/4] drm/simple-kms: Let DRM core send VBLANK events by default Date: Thu, 16 Jan 2020 07:41:07 +0100 Message-ID: <20200116064107.GB8400@dvetter-linux.ger.corp.intel.com> References: <20200115125226.13843-1-tzimmermann@suse.de> <20200115125226.13843-5-tzimmermann@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20200115125226.13843-5-tzimmermann@suse.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" To: Thomas Zimmermann Cc: david@lechnology.com, oleksandr_andrushchenko@epam.com, airlied@linux.ie, sam@ravnborg.org, dri-devel@lists.freedesktop.org, maarten.lankhorst@linux.intel.com, mripard@kernel.org, virtualization@lists.linux-foundation.org, hdegoede@redhat.com, noralf@tronnes.org, daniel@ffwll.ch, xen-devel@lists.xenproject.org, emil.velikov@collabora.com, sean@poorly.run, laurent.pinchart@ideasonboard.com List-Id: virtualization@lists.linuxfoundation.org On Wed, Jan 15, 2020 at 01:52:26PM +0100, Thomas Zimmermann wrote: > In drm_atomic_helper_fake_vblank() the DRM core sends out VBLANK events > if struct drm_crtc_state.no_vblank is enabled in the check() callbacks. > > For drivers that have neither an enable_vblank() callback nor a check() > callback, the simple-KMS helpers enable VBLANK generation by default. This > simplifies bochs, udl, several tiny drivers, and drivers based upon MIPI > DPI helpers. The driver for Xen explicitly disables no_vblank, as it has > its own logic for sending these events. > > Signed-off-by: Thomas Zimmermann > diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c > index 15fb516ae2d8..4414c7a5b2ce 100644 > --- a/drivers/gpu/drm/drm_simple_kms_helper.c > +++ b/drivers/gpu/drm/drm_simple_kms_helper.c > @@ -146,10 +146,21 @@ static int drm_simple_kms_plane_atomic_check(struct drm_plane *plane, > if (!plane_state->visible) > return 0; > > - if (!pipe->funcs || !pipe->funcs->check) > - return 0; > - > - return pipe->funcs->check(pipe, plane_state, crtc_state); > + if (pipe->funcs) { > + if (pipe->funcs->check) > + return pipe->funcs->check(pipe, plane_state, > + crtc_state); > + if (pipe->funcs->enable_vblank) > + return 0; > + } > + > + /* Drivers without VBLANK support have to fake VBLANK events. As > + * there's no check() callback to enable this, set the no_vblank > + * field by default. > + */ The ->check callback is right above this comment ... I'm confused. > + crtc_state->no_vblank = true; That's kinda not what I meant with handling this automatically. Instead something like this: diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gpu/drm/drm_atomic_state_helper.c index 7cf3cf936547..23d2f51fc1d4 100644 --- a/drivers/gpu/drm/drm_atomic_state_helper.c +++ b/drivers/gpu/drm/drm_atomic_state_helper.c @@ -149,6 +149,11 @@ void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc, /* Self refresh should be canceled when a new update is available */ state->active = drm_atomic_crtc_effectively_active(state); state->self_refresh_active = false; + + if (drm_dev_has_vblank(crtc->dev)) + state->no_vblank = true; + else + state->no_vblank = false; } EXPORT_SYMBOL(__drm_atomic_helper_crtc_duplicate_state); diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index 1659b13b178c..32cab3d3c872 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -81,6 +81,12 @@ */ #define DRM_REDUNDANT_VBLIRQ_THRESH_NS 1000000 +/* FIXME roll this out here in this file */ +bool drm_dev_has_vblank(dev) +{ + return dev->num_crtcs; +} + static bool drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe, ktime_t *tvblank, bool in_vblank_irq); But maybe move the default value to some other/better place in the atomic helpers, not sure what the best one is. Plus then in the documentation patch also highlight the link between crtc_state->no_vblank and drm_dev_has_vblank respectively drm_device.num_crtcs. That should plug this issue once for all across the board. There's still the fun between having the vblank callbacks and the drm_vblank setup, but that's a much older can of worms ... -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch