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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 450A6C74A5B for ; Tue, 21 Mar 2023 13:58:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231334AbjCUN6n (ORCPT ); Tue, 21 Mar 2023 09:58:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59392 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231276AbjCUN6j (ORCPT ); Tue, 21 Mar 2023 09:58:39 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EFF925FDA; Tue, 21 Mar 2023 06:58:37 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A3686B816A9; Tue, 21 Mar 2023 13:58:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DFAEAC433EF; Tue, 21 Mar 2023 13:58:32 +0000 (UTC) Message-ID: <1a323f49-20e4-46dd-12ac-d991cd257330@xs4all.nl> Date: Tue, 21 Mar 2023 14:58:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH] media: meson: vdec: esparser: check parsing state with hardware write pointer Content-Language: en-US To: Christian Hewitt Cc: Neil Armstrong , Mauro Carvalho Chehab , Greg Kroah-Hartman , Kevin Hilman , Jerome Brunet , Martin Blumenstingl , linux-media@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-staging@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Neil Armstrong , Dan Carpenter References: <20230123094300.2816812-1-christianshewitt@gmail.com> From: Hans Verkuil In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Christian, On 23/01/2023 13:04, Dan Carpenter wrote: > On Mon, Jan 23, 2023 at 09:43:00AM +0000, Christian Hewitt wrote: >> From: Neil Armstrong >> >> Also check the hardware write pointer to check if ES Parser has stalled. >> > > Presumably this is something which has happens in real life? Say a user > has this hardware and is wondering if this patch fixes their bug, what > does this bug look like to them? > > Please add a Fixes tag. I'm marking this as Changes Requested in patchwork. Dan has good comments, and in general, if something is 'weird', then it needs to be commented carefully. Regards, Hans > >> Signed-off-by: Neil Armstrong >> Signed-off-by: Christian Hewitt >> --- >> drivers/staging/media/meson/vdec/esparser.c | 15 +++++++++++---- >> 1 file changed, 11 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/staging/media/meson/vdec/esparser.c b/drivers/staging/media/meson/vdec/esparser.c >> index df5956c6141d..41b705f999b2 100644 >> --- a/drivers/staging/media/meson/vdec/esparser.c >> +++ b/drivers/staging/media/meson/vdec/esparser.c >> @@ -300,6 +300,7 @@ esparser_queue(struct amvdec_session *sess, struct vb2_v4l2_buffer *vbuf) >> u32 num_dst_bufs = 0; >> u32 offset; >> u32 pad_size; >> + u32 wp, wp2; >> >> /* >> * When max ref frame is held by VP9, this should be -= 3 to prevent a >> @@ -354,15 +355,21 @@ esparser_queue(struct amvdec_session *sess, struct vb2_v4l2_buffer *vbuf) >> } >> >> pad_size = esparser_pad_start_code(core, vb, payload_size); >> + wp = amvdec_read_parser(core, PARSER_VIDEO_WP); >> ret = esparser_write_data(core, phy, payload_size + pad_size); >> + wp2 = amvdec_read_parser(core, PARSER_VIDEO_WP); >> > > Why is check not done inside the esparser_write_data() function? It > really feels like doing a write where nothing happens should be a bug > for both callers... > > The esparser_write_data() function returns > 0 on success, 0 on timeout > (I guess timeout is an error-ish) and negative if the user presses > CTR-C. There are no comments to explain the unusual returns. Could we > clean this up so it just returns negatives on error and zero on success > or if not then let's add a comment explaining what's going on? > >> if (ret <= 0) { >> - dev_warn(core->dev, "esparser: input parsing error\n"); >> - amvdec_remove_ts(sess, vb->timestamp); >> - v4l2_m2m_buf_done(vbuf, VB2_BUF_STATE_ERROR); >> amvdec_write_parser(core, PARSER_FETCH_CMD, 0); >> >> - return 0; >> + if (ret < 0 || wp2 == wp) { > > So in this patch if there is a timeout but something was written then > that's kind of a success path? > > regards, > dan carpenter > >> + dev_err(core->dev, "esparser: input parsing error ret %d (%x <=> %x)\n", >> + ret, wp, wp2); >> + amvdec_remove_ts(sess, vb->timestamp); >> + v4l2_m2m_buf_done(vbuf, VB2_BUF_STATE_ERROR); >> + >> + return 0; >> + } >> } >> >> atomic_inc(&sess->esparser_queued_bufs); >