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[2620:137:e000::3:1]) by mx.google.com with ESMTPS id s20-20020a63dc14000000b0056336fb99aasi8043565pgg.850.2023.12.04.05.46.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Dec 2023 05:46:33 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:1 as permitted sender) client-ip=2620:137:e000::3:1; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:1 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by morse.vger.email (Postfix) with ESMTP id 04056807C876; Mon, 4 Dec 2023 05:45:29 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at morse.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233894AbjLDNpJ convert rfc822-to-8bit (ORCPT + 99 others); Mon, 4 Dec 2023 08:45:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229711AbjLDNpI (ORCPT ); Mon, 4 Dec 2023 08:45:08 -0500 Received: from metis.whiteo.stw.pengutronix.de (metis.whiteo.stw.pengutronix.de [IPv6:2a0a:edc0:2:b01:1d::104]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 001B8D2 for ; Mon, 4 Dec 2023 05:45:14 -0800 (PST) Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1rA9G0-0008CM-0H; Mon, 04 Dec 2023 14:45:08 +0100 Received: from [2a0a:edc0:0:900:1d::4e] (helo=lupine) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1rA9Fy-00DX3R-42; Mon, 04 Dec 2023 14:45:06 +0100 Received: from pza by lupine with local (Exim 4.96) (envelope-from ) id 1rA9Fy-000H8w-04; Mon, 04 Dec 2023 14:45:06 +0100 Message-ID: <82a42b2478c36a27bd56660f8d4b4da40b9fd897.camel@pengutronix.de> Subject: Re: [PATCH v2 02/36] media: chips-media: coda: Remove useless setting of min_buffers_needed From: Philipp Zabel To: Benjamin Gaignard , hverkuil@xs4all.nl, mchehab@kernel.org, tfiga@chromium.org, m.szyprowski@samsung.com, matt.ranostay@konsulko.com Cc: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-staging@lists.linux.dev, kernel@collabora.com Date: Mon, 04 Dec 2023 14:45:05 +0100 In-Reply-To: <20231204132323.22811-3-benjamin.gaignard@collabora.com> References: <20231204132323.22811-1-benjamin.gaignard@collabora.com> <20231204132323.22811-3-benjamin.gaignard@collabora.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT User-Agent: Evolution 3.46.4-2 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.whiteo.stw.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org X-Spam-Status: No, score=-0.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on morse.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (morse.vger.email [0.0.0.0]); Mon, 04 Dec 2023 05:45:29 -0800 (PST) Hi Benjamin, On Mo, 2023-12-04 at 14:22 +0100, Benjamin Gaignard wrote: > This driver uses min_buffers_needed which vb2 uses to ensure > start_streaming is called when at least 'min_buffers_needed' > buffers are queued. However, this driver doesn't need this, > it can stream fine without any buffers queued. > Just drop this unnecessary restriction. Did you test this? I think there currently is some initialization in start_streaming() that doesn't quite work when starting without any buffers queued (it returns -EINVAL if called with count < 1). For example, the CODA960 decoder initialization expects 512 bytes of bitstream payload to run SEQ_INIT, and for JPEG decoding it tries to determine chroma subsampling from the JPEG header. regards Philipp