From patchwork Wed Mar 18 13:21:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ezequiel Garcia X-Patchwork-Id: 210572 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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, UNPARSEABLE_RELAY, USER_AGENT_GIT autolearn=unavailable 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 76891C5ACD7 for ; Wed, 18 Mar 2020 13:21:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 570F320768 for ; Wed, 18 Mar 2020 13:21:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727061AbgCRNVx (ORCPT ); Wed, 18 Mar 2020 09:21:53 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:44456 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726638AbgCRNVx (ORCPT ); Wed, 18 Mar 2020 09:21:53 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: ezequiel) with ESMTPSA id 8D2D229661B From: Ezequiel Garcia To: linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Tomasz Figa , Nicolas Dufresne , kernel@collabora.com, Jonas Karlman , Heiko Stuebner , Hans Verkuil , Alexandre Courbot , Jeffrey Kardatzke , Rob Herring , Ezequiel Garcia , Nicolas Dufresne Subject: [PATCH v2 1/8] v4l2-mem2mem: return CAPTURE buffer first Date: Wed, 18 Mar 2020 10:21:01 -0300 Message-Id: <20200318132108.21873-2-ezequiel@collabora.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200318132108.21873-1-ezequiel@collabora.com> References: <20200318132108.21873-1-ezequiel@collabora.com> MIME-Version: 1.0 Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org When the request API is used, typically an OUTPUT (src) buffer will be part of a request. A userspace process will be typically blocked, waiting on the request file descriptor. Returning the OUTPUT (src) buffer will wake-up such processes, who will immediately attempt to dequeue the CAPTURE buffer, only to find it's still unavailable. Therefore, change v4l2_m2m_buf_done_and_job_finish returning the CAPTURE (dst) buffer first, to avoid signalling the request file descriptor prematurely, i.e. before the CAPTURE buffer is done. When the request API is not used, this change should have no impact. Tested-by: Nicolas Dufresne Signed-off-by: Ezequiel Garcia --- drivers/media/v4l2-core/v4l2-mem2mem.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c index 8986c31176e9..62ac9424c92a 100644 --- a/drivers/media/v4l2-core/v4l2-mem2mem.c +++ b/drivers/media/v4l2-core/v4l2-mem2mem.c @@ -504,12 +504,21 @@ void v4l2_m2m_buf_done_and_job_finish(struct v4l2_m2m_dev *m2m_dev, if (WARN_ON(!src_buf || !dst_buf)) goto unlock; - v4l2_m2m_buf_done(src_buf, state); dst_buf->is_held = src_buf->flags & V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF; if (!dst_buf->is_held) { v4l2_m2m_dst_buf_remove(m2m_ctx); v4l2_m2m_buf_done(dst_buf, state); } + /* + * If the request API is being used, returning the OUTPUT + * (src) buffer will wake-up any process waiting on the + * request file descriptor. + * + * Therefore, return the CAPTURE (dst) buffer first, + * to avoid signalling the request file descriptor + * before the CAPTURE buffer is done. + */ + v4l2_m2m_buf_done(src_buf, state); schedule_next = _v4l2_m2m_job_finish(m2m_dev, m2m_ctx); unlock: spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);