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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1h3azw-0008C5-3k; Tue, 12 Mar 2019 06:34:48 +0000 Received: from bhuna.collabora.co.uk ([46.235.227.227]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1h3azs-0008Ba-AX; Tue, 12 Mar 2019 06:34:46 +0000 Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:b93f:9fae:b276:a89a]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id B4AE627B896; Tue, 12 Mar 2019 06:34:41 +0000 (GMT) Date: Tue, 12 Mar 2019 07:34:38 +0100 From: Boris Brezillon To: Helen Koike Subject: Re: [PATCH v2 1/5] drm/rockchip: fix fb references in async update Message-ID: <20190312073438.05ad8173@collabora.com> In-Reply-To: <20190312022204.2775-2-helen.koike@collabora.com> References: <20190312022204.2775-1-helen.koike@collabora.com> <20190312022204.2775-2-helen.koike@collabora.com> Organization: Collabora X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190311_233444_623205_9EF0CF98 X-CRM114-Status: GOOD ( 27.65 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: andrey.grodzovsky@amd.com, =?UTF-8?B?U3TDqXBoYW5l?= Marchesin , Heiko =?UTF-8?B?U3TDvGJuZXI=?= , Sean Paul , David Airlie , daniel.vetter@ffwll.ch, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Tomasz Figa , linux-rockchip@lists.infradead.org, Sandy Huang , Daniel Vetter , kernel@collabora.com, harry.wentland@amd.com, nicholas.kazlauskas@amd.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, 11 Mar 2019 23:21:59 -0300 Helen Koike wrote: > In the case of async update, modifications are done in place, i.e. in the > current plane state, so the new_state is prepared and the new_state is > cleanup up (instead of the old_state, diferrently on what happen in a ^ cleaned up ^ differently (but maybe "unlike what happens" is more appropriate here). > normal sync update). > To cleanup the old_fb properly, it needs to be placed in the new_state > in the end of async_update, so cleanup call will unreference the old_fb > correctly. > > Also, the previous code had a: > > plane_state = plane->funcs->atomic_duplicate_state(plane); > ... > swap(plane_state, plane->state); > > if (plane->state->fb && plane->state->fb != new_state->fb) { > ... > } > > Which was wrong, as the fb were just assigned to be equal, so this if > statement nevers evaluates to true. > > Another details is that the function drm_crtc_vblank_get() can only be > called when vop->is_enabled is true, otherwise it has no effect and > trows a WARN_ON(). > > Calling drm_atomic_set_fb_for_plane() (which get a referent of the new > fb and pus the old fb) is not required, as it is taken care by > drm_mode_cursor_universal() when calling > drm_atomic_helper_update_plane(). > > Signed-off-by: Helen Koike > > --- > Hello, > > I tested on the rockchip ficus v1.1 using igt plane_cursor_legacy and > kms_cursor_legacy and I didn't see any regressions. > > Changes in v2: None > > drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 42 ++++++++++++--------- > 1 file changed, 24 insertions(+), 18 deletions(-) > > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c > index c7d4c6073ea5..a1ee8c156a7b 100644 > --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c > @@ -912,30 +912,31 @@ static void vop_plane_atomic_async_update(struct drm_plane *plane, > struct drm_plane_state *new_state) > { > struct vop *vop = to_vop(plane->state->crtc); > - struct drm_plane_state *plane_state; > + struct drm_framebuffer *old_fb = plane->state->fb; > > - plane_state = plane->funcs->atomic_duplicate_state(plane); > - plane_state->crtc_x = new_state->crtc_x; > - plane_state->crtc_y = new_state->crtc_y; > - plane_state->crtc_h = new_state->crtc_h; > - plane_state->crtc_w = new_state->crtc_w; > - plane_state->src_x = new_state->src_x; > - plane_state->src_y = new_state->src_y; > - plane_state->src_h = new_state->src_h; > - plane_state->src_w = new_state->src_w; > - > - if (plane_state->fb != new_state->fb) > - drm_atomic_set_fb_for_plane(plane_state, new_state->fb); > - > - swap(plane_state, plane->state); > - > - if (plane->state->fb && plane->state->fb != new_state->fb) { > + /* > + * A scanout can still be occurring, so we can't drop the reference to > + * the old framebuffer. To solve this we get a reference to old_fb and > + * set a worker to release it later. Hm, doesn't look like an async update to me if we have to wait for the next VBLANK to happen to get the new content on the screen. Maybe we should reject async updates when old_fb != new_fb in the rk ->async_check() hook. > + */ > + if (vop->is_enabled && > + plane->state->fb && plane->state->fb != new_state->fb) { > drm_framebuffer_get(plane->state->fb); > WARN_ON(drm_crtc_vblank_get(plane->state->crtc) != 0); > drm_flip_work_queue(&vop->fb_unref_work, plane->state->fb); > set_bit(VOP_PENDING_FB_UNREF, &vop->pending); > } In any case, I think this should be called after vop_plane_atomic_update() to prevent the situation where the VBLANK event happens between this point and the following vop_plane_atomic_update() call. > > + plane->state->crtc_x = new_state->crtc_x; > + plane->state->crtc_y = new_state->crtc_y; > + plane->state->crtc_h = new_state->crtc_h; > + plane->state->crtc_w = new_state->crtc_w; > + plane->state->src_x = new_state->src_x; > + plane->state->src_y = new_state->src_y; > + plane->state->src_h = new_state->src_h; > + plane->state->src_w = new_state->src_w; > + plane->state->fb = new_state->fb; Any reason not to use swap() here and reference plane->state->fb instead of new_state->fb after this point? > + > if (vop->is_enabled) { > rockchip_drm_psr_inhibit_get_state(new_state->state); > vop_plane_atomic_update(plane, plane->state); > @@ -945,7 +946,12 @@ static void vop_plane_atomic_async_update(struct drm_plane *plane, > rockchip_drm_psr_inhibit_put_state(new_state->state); > } > > - plane->funcs->atomic_destroy_state(plane, plane_state); > + /* > + * In async update we perform inplace modifications and release the > + * new_state. The following is required so we release the reference of > + * the old framebuffer. > + */ > + new_state->fb = old_fb; > } > > static const struct drm_plane_helper_funcs plane_helper_funcs = { _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel