From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82E2AC43381 for ; Tue, 12 Mar 2019 15:34:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 46EE92083D for ; Tue, 12 Mar 2019 15:34:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726807AbfCLPez (ORCPT ); Tue, 12 Mar 2019 11:34:55 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:60084 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726218AbfCLPez (ORCPT ); Tue, 12 Mar 2019 11:34:55 -0400 Received: from [IPv6:2804:431:9719:798c:867b:ebff:fe52:de60] (unknown [IPv6:2804:431:9719:798c:867b:ebff:fe52:de60]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: koike) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 2A00A281027; Tue, 12 Mar 2019 15:34:48 +0000 (GMT) Subject: Re: [PATCH v2 1/5] drm/rockchip: fix fb references in async update To: Boris Brezillon Cc: dri-devel@lists.freedesktop.org, nicholas.kazlauskas@amd.com, andrey.grodzovsky@amd.com, daniel.vetter@ffwll.ch, linux-kernel@vger.kernel.org, Tomasz Figa , David Airlie , Sean Paul , kernel@collabora.com, harry.wentland@amd.com, =?UTF-8?Q?St=c3=a9phane_Marchesin?= , Sandy Huang , linux-rockchip@lists.infradead.org, =?UTF-8?Q?Heiko_St=c3=bcbner?= , linux-arm-kernel@lists.infradead.org, Daniel Vetter References: <20190312022204.2775-1-helen.koike@collabora.com> <20190312022204.2775-2-helen.koike@collabora.com> <20190312073438.05ad8173@collabora.com> From: Helen Koike Openpgp: preference=signencrypt Autocrypt: addr=helen.koike@collabora.com; keydata= mQINBFmOMD4BEADb2nC8Oeyvklh+ataw2u/3mrl+hIHL4WSWtii4VxCapl9+zILuxFDrxw1p XgF3cfx7g9taWBrmLE9VEPwJA6MxaVnQuDL3GXxTxO/gqnOFgT3jT+skAt6qMvoWnhgurMGH wRaA3dO4cFrDlLsZIdDywTYcy7V2bou81ItR5Ed6c5UVX7uTTzeiD/tUi8oIf0XN4takyFuV Rf09nOhi24bn9fFN5xWHJooFaFf/k2Y+5UTkofANUp8nn4jhBUrIr6glOtmE0VT4pZMMLT63 hyRB+/s7b1zkOofUGW5LxUg+wqJXZcOAvjocqSq3VVHcgyxdm+Nv0g9Hdqo8bQHC2KBK86VK vB+R7tfv7NxVhG1sTW3CQ4gZb0ZugIWS32Mnr+V+0pxci7QpV3jrtVp5W2GA5HlXkOyC6C7H Ao7YhogtvFehnlUdG8NrkC3HhCTF8+nb08yGMVI4mMZ9v/KoIXKC6vT0Ykz434ed9Oc9pDow VUqaKi3ey96QczfE4NI029bmtCY4b5fucaB/aVqWYRH98Jh8oIQVwbt+pY7cL5PxS7dQ/Zuz 6yheqDsUGLev1O3E4R8RZ8jPcfCermL0txvoXXIA56t4ZjuHVcWEe2ERhLHFGq5Zw7KC6u12 kJoiZ6WDBYo4Dp+Gd7a81/WsA33Po0j3tk/8BWoiJCrjXzhtRwARAQABtCdIZWxlbiBLb2lr ZSA8aGVsZW4ua29pa2VAY29sbGFib3JhLmNvbT6JAlQEEwEKAD4CGwEFCwkIBwMFFQoJCAsF 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en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/12/19 3:34 AM, Boris Brezillon wrote: > 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. Unless I am misunderstanding this, we don't wait here, we just grab a reference to the fb in case it is being still used by the hw, so it doesn't get released prematurely. > >> + */ >> + 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. ack, I'll update it in the next version. > >> >> + 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? I had the impression I had to do this in one of my tests, but re-testing now and re-looking at the code this doesn't seem to be necessary. I'll use a swap() in the next version. Thanks for your feedback. Helen > >> + >> 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 = { >