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=-17.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 57690C433E0 for ; Mon, 22 Mar 2021 15:34:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2B95261972 for ; Mon, 22 Mar 2021 15:34:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231321AbhCVPeF (ORCPT ); Mon, 22 Mar 2021 11:34:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:43670 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230455AbhCVPde (ORCPT ); Mon, 22 Mar 2021 11:33:34 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D549F61994; Mon, 22 Mar 2021 15:33:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616427214; bh=KzP4v3tkS2uLc6oExhJwyYXag2zCF3wXfwH/syF61Fc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=LhOmt0R/2cqLUcoiL7VNXseG8mb15jcvsaG0nbycY6FdzpJWlBAfqxzUoSXca4IHB KEHTDSyTLRgQz6Ei9Rwu+scz+azSLZWrCutipQP9hL7ctcuUrMTHLHuKcnjRus/cdw vdBGbHYLkv3S8Vp6OQTX+ReTeHI/i7ufu/bjJZP/mF3kWapkIYAsdX5CuNp7bOPk7l j3WSpdXdrdFlI8P1r1S6R1yWbHR5OMukVGZTig3Oay+ZKYGESDCVJlEtzF62WHQElL B2JLzLJka7SccULysH7unwSifpcjl0vYI0yloFRH1M7IvHUknjnPlkRaaZUKffyeGp u+0T8PROuuPbg== Date: Mon, 22 Mar 2021 16:33:29 +0100 From: Mauro Carvalho Chehab To: Marc Gonzalez Cc: linux-media , Brad Love , Sean Young , Arnd Bergmann , LKML Subject: Re: [RFC 4/4] media: dvb_frontend: disable zigzag mode if not possible Message-ID: <20210322163329.4afe27ed@coco.lan> In-Reply-To: <20bb2501-8307-185e-ebec-a83488353a0b@free.fr> References: <974065921c41fa0c97700196de1d921c95fafaaf.1592419750.git.mchehab+huawei@kernel.org> <20bb2501-8307-185e-ebec-a83488353a0b@free.fr> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Em Thu, 18 Jun 2020 11:50:54 +0200 Marc Gonzalez escreveu: > On 17/06/2020 20:52, Mauro Carvalho Chehab wrote: > > > For the zigzag to work, the core needs to have a frequency > > shift. Without that, the zigzag code will just try re-tuning > > several times at the very same frequency, with seems wrong. > > s/with/which > > Suggest: "the core requires a frequency shift value" > > > So, add a warning when this happens, and fall back to the > > single-shot mode. > > > > Signed-off-by: Mauro Carvalho Chehab > > --- > > drivers/media/dvb-core/dvb_frontend.c | 141 +++++++++++++++----------- > > 1 file changed, 79 insertions(+), 62 deletions(-) > > It's hard to discern in the diff what is just white-space adjustment > from one less tab, and what is new code that requires more scrutiny. > I'll try applying the patch, and then diff -w. > Yes, that's much better. > > > diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c > > index ed85dc2a9183..cb577924121e 100644 > > --- a/drivers/media/dvb-core/dvb_frontend.c > > +++ b/drivers/media/dvb-core/dvb_frontend.c > > @@ -642,6 +642,9 @@ static void dvb_frontend_wakeup(struct dvb_frontend *fe) > > wake_up_interruptible(&fepriv->wait_queue); > > } > > > > +static u32 dvb_frontend_get_stepsize(struct dvb_frontend *fe); > > +static void prepare_tuning_algo_parameters(struct dvb_frontend *fe); > > + > > static int dvb_frontend_thread(void *data) > > { > > struct dvb_frontend *fe = data; > > @@ -696,78 +699,92 @@ static int dvb_frontend_thread(void *data) > > fepriv->reinitialise = 0; > > } > > > > - /* do an iteration of the tuning loop */ > > - if (fe->ops.get_frontend_algo) { > > + if (fe->ops.get_frontend_algo) > > algo = fe->ops.get_frontend_algo(fe); > > - switch (algo) { > > - case DVBFE_ALGO_HW: > > - dev_dbg(fe->dvb->device, "%s: Frontend ALGO = DVBFE_ALGO_HW\n", __func__); > > + else > > + algo = DVBFE_ALGO_SW; > > > > - if (fepriv->state & FESTATE_RETUNE) { > > - dev_dbg(fe->dvb->device, "%s: Retune requested, FESTATE_RETUNE\n", __func__); > > - re_tune = true; > > - fepriv->state = FESTATE_TUNED; > > - } else { > > - re_tune = false; > > - } > > + /* do an iteration of the tuning loop */ > > + switch (algo) { > > + case DVBFE_ALGO_SW: > > + prepare_tuning_algo_parameters(fe); > > > > - if (fe->ops.tune) > > - fe->ops.tune(fe, re_tune, fepriv->tune_mode_flags, &fepriv->delay, &s); > > - > > - if (s != fepriv->status && !(fepriv->tune_mode_flags & FE_TUNE_MODE_ONESHOT)) { > > - dev_dbg(fe->dvb->device, "%s: state changed, adding current state\n", __func__); > > - dvb_frontend_add_event(fe, s); > > - fepriv->status = s; > > - } > > - break; > > - case DVBFE_ALGO_SW: > > + if (fepriv->max_drift) { > > dev_dbg(fe->dvb->device, "%s: Frontend ALGO = DVBFE_ALGO_SW\n", __func__); > > dvb_frontend_swzigzag(fe); > > break; > > - case DVBFE_ALGO_CUSTOM: > > - dev_dbg(fe->dvb->device, "%s: Frontend ALGO = DVBFE_ALGO_CUSTOM, state=%d\n", __func__, fepriv->state); > > - if (fepriv->state & FESTATE_RETUNE) { > > - dev_dbg(fe->dvb->device, "%s: Retune requested, FESTAT_RETUNE\n", __func__); > > - fepriv->state = FESTATE_TUNED; > > + } > > + > > + /* > > + * See prepare_tuning_algo_parameters(): > > + * - Some standards may not use zigzag. > > + */ > > + if (!dvb_frontend_get_stepsize(fe)) > > + dev_warn(fe->dvb->device, > > + "disabling sigzag, as frontend doesn't set frequency step size\n"); > > s/sigzag/zigzag > > I don't understand why you're calling dvb_frontend_get_stepsize() again? > prepare_tuning_algo_parameters() already tried its best to set fepriv->step_size > > Why not just: > > if (fepriv->max_drift) > do the zigzag > else > warn that zigzag is disabled > > > + > > + /* fall through */ > > Why would you want to fall through from DVBFE_ALGO_SW to DVBFE_ALGO_HW? > I think this changes the behavior before the patch. I double-checked this patch. What happens is that there are 3 types of DVB devices: 1. Devices where the Zigzag happens at the hardware level, automatically (DVBFE_ALGO_HW). All they need is to call fe->ops.tune() logic once; 2. Devices that have their own hardware-assisted zigzag logic. Those are handled via DVBFE_ALGO_CUSTOM logic. Those use an special callback: fe->ops.search(fe). 3. Devices that require the Kernel to do zigzag (DVBFE_ALGO_SW). Those should set max_drift and other fields, in order to setup the zigzag steps. In other words, a device driver which uses DVBFE_ALGO_SW should provide the vars that are needed for the zigzag to work, as otherwise, the software zigzag would be just wasting time, as it won't be different than a device driver using DVBFE_ALGO_HW. What the above patch does is to generate a warning when DVBFE_ALGO_SW is used without setting the frequency shift, which is an uAPI/kAPI violation. On such cases, it will fallback to DVBFE_ALGO_HW. The main issue is that testing this patch is not trivial. As you pointed, it can cause regressions. So, instead of this patch, I'll merge one that will just print a warning. We need to fix the frontend drivers case by case. Thanks, Mauro