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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 37D02C433E2 for ; Tue, 15 Sep 2020 12:05:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 06B6D206B2 for ; Tue, 15 Sep 2020 12:05:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726382AbgIOMFW (ORCPT ); Tue, 15 Sep 2020 08:05:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38206 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726461AbgIOLyU (ORCPT ); Tue, 15 Sep 2020 07:54:20 -0400 Received: from michel.telenet-ops.be (michel.telenet-ops.be [IPv6:2a02:1800:110:4::f00:18]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9BEC4C061788 for ; Tue, 15 Sep 2020 04:53:34 -0700 (PDT) Received: from ramsan ([84.195.186.194]) by michel.telenet-ops.be with bizsmtp id UBtV2302Q4C55Sk06BtVmK; Tue, 15 Sep 2020 13:53:29 +0200 Received: from geert (helo=localhost) by ramsan with local-esmtp (Exim 4.90_1) (envelope-from ) id 1kI9Wb-0008H5-Gl; Tue, 15 Sep 2020 13:53:29 +0200 Date: Tue, 15 Sep 2020 13:53:29 +0200 (CEST) From: Geert Uytterhoeven To: "Daniel W. S. Almeida" cc: mchehab+huawei@kernel.org, r.verdejo@samsung.com, nicolas@ndufresne.ca, linux-media@vger.kernel.org, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, linux-kernel@vger.kernel.org Subject: Re: [v10 3/4] media: vidtv: add a bridge driver In-Reply-To: <20200821125848.1092958-4-dwlsalmeida@gmail.com> Message-ID: References: <20200821125848.1092958-1-dwlsalmeida@gmail.com> <20200821125848.1092958-4-dwlsalmeida@gmail.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Daniel, On Fri, 21 Aug 2020, Daniel W. S. Almeida wrote: > From: "Daniel W. S. Almeida" > > Digital TV devices consist of several independent hardware components > which are controlled by different drivers. > Each media device is controlled by a group of cooperating drivers with the > bridge driver as the main driver. > > This patch adds a bridge driver for the Virtual Digital TV driver [vidtv]. This is now commit f90cf6079bf67988 ("media: vidtv: add a bridge driver") in the media tree. noreply@ellerman.id.au reported the following error for an m68k allmodconfig build: ERROR: modpost: "__udivdi3" [drivers/media/test-drivers/vidtv/dvb-vidtv-bridge.ko] undefined! Presumably this fails on other 32-bit platforms, too. > --- /dev/null > +++ b/drivers/media/test-drivers/vidtv/vidtv_mux.c > +static u32 vidtv_mux_check_mux_rate(struct vidtv_mux *m) > +{ > + /* > + * attempt to maintain a constant mux rate, padding with null packets > + * if needed > + */ > + > + u32 nbytes = 0; /* the number of bytes written by this function */ > + > + u64 nbytes_expected; /* the number of bytes we should have written */ > + u64 nbytes_streamed; /* the number of bytes we actually wrote */ > + u32 num_null_pkts; /* number of null packets to bridge the gap */ > + > + u64 elapsed_time_msecs = jiffies_to_usecs(m->timing.current_jiffies - > + m->timing.past_jiffies); > + > + elapsed_time_msecs = min(elapsed_time_msecs, (u64)VIDTV_MAX_SLEEP_USECS / 1000); > + nbytes_expected = div64_u64(m->mux_rate_kbytes_sec * 1000, MSEC_PER_SEC); Seriously?!? You multiply by 1000 first, followed by a division by 1000 using an expensive 64-by-64 division? > + nbytes_expected *= elapsed_time_msecs; > + > + nbytes_streamed = m->mux_buf_offset; > + > + if (nbytes_streamed < nbytes_expected) { > + /* can't write half a packet: roundup to a 188 multiple */ > + nbytes_expected = roundup(nbytes_expected - nbytes_streamed, TS_PACKET_LEN); drivers/media/test-drivers/vidtv/vidtv_mux.o: In function `vidtv_mux_tick': vidtv_mux.c:(.text+0x788): undefined reference to `__udivdi3' This is a 64-by-32 division, hence it should use a helper from . However, I'm wondering if "nbytes_expected - nbytes_streamed" is guaranteed to be a "small" number, hence a 32-by-32 division would be sufficient? > + num_null_pkts = nbytes_expected / TS_PACKET_LEN; Likewise. > + nbytes += vidtv_mux_pad_with_nulls(m, num_null_pkts); > + } > + > + return nbytes; > +} > --- /dev/null > +++ b/drivers/media/test-drivers/vidtv/vidtv_s302m.c > +static void vidtv_s302m_compute_pts(struct vidtv_encoder *e) > +{ > + u64 count = e->sample_count; > + struct vidtv_access_unit *au = e->access_units; > + > + while (au) { > + count += au->num_samples; > + > + au->pts = count * > + CLOCK_UNIT_90KHZ / e->sampling_rate_hz; drivers/media/test-drivers/vidtv/vidtv_s302m.o: In function `vidtv_s302m_encode': vidtv_s302m.c:(.text+0x2ac): undefined reference to `__udivdi3' Likewise. > + > + au = au->next; > + } > +} Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds