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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY 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 D6E5AC433B4 for ; Tue, 27 Apr 2021 15:18:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE8D1613EE for ; Tue, 27 Apr 2021 15:18:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238679AbhD0PT1 (ORCPT ); Tue, 27 Apr 2021 11:19:27 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:60450 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237656AbhD0PTZ (ORCPT ); Tue, 27 Apr 2021 11:19:25 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: ezequiel) with ESMTPSA id 132381F4265E Message-ID: <95ea572e201545b27ff9f48313f7aaea157d4764.camel@collabora.com> Subject: Re: [PATCH v3 79/79] media: hantro: document the usage of pm_runtime_get_sync() From: Ezequiel Garcia To: Robin Murphy , Mauro Carvalho Chehab Cc: linuxarm@huawei.com, mauro.chehab@huawei.com, Greg Kroah-Hartman , Mauro Carvalho Chehab , Philipp Zabel , devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org Date: Tue, 27 Apr 2021 12:18:32 -0300 In-Reply-To: <02948673-9572-a570-d28e-03a7208f39e1@arm.com> References: <230f22170db7fa57b49cff4570cef15bf11b2ad5.1619519080.git.mchehab+huawei@kernel.org> <02948673-9572-a570-d28e-03a7208f39e1@arm.com> Organization: Collabora Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.2-1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2021-04-27 at 16:08 +0100, Robin Murphy wrote: > On 2021-04-27 11:27, Mauro Carvalho Chehab wrote: > > Despite other *_get()/*_put() functions, where usage count is > > incremented only if not errors, the pm_runtime_get_sync() has > > a different behavior, incrementing the counter *even* on > > errors. > > > > That's an error prone behavior, as people often forget to > > decrement the usage counter. > > > > However, the hantro driver depends on this behavior, as it > > will decrement the usage_count unconditionally at the m2m > > job finish time, which makes sense. > > > > So, intead of using the pm_runtime_resume_and_get() that > > would decrement the counter on error, keep the current > > API, but add a documentation explaining the rationale for > > keep using pm_runtime_get_sync(). > > > > Signed-off-by: Mauro Carvalho Chehab > > --- > >   drivers/staging/media/hantro/hantro_drv.c | 7 +++++++ > >   1 file changed, 7 insertions(+) > > > > diff --git a/drivers/staging/media/hantro/hantro_drv.c b/drivers/staging/media/hantro/hantro_drv.c > > index 595e82a82728..96f940c1c85c 100644 > > --- a/drivers/staging/media/hantro/hantro_drv.c > > +++ b/drivers/staging/media/hantro/hantro_drv.c > > @@ -155,6 +155,13 @@ static void device_run(void *priv) > >         ret = clk_bulk_enable(ctx->dev->variant->num_clocks, ctx->dev->clocks); > >         if (ret) > >                 goto err_cancel_job; > > ..except this can also cause the same pm_runtime_put_autosuspend() call > without even reaching the "matching" get below, so rather than some kind > of cleverness it seems more like it's just broken :/ > Indeed, I was trying to find time to cook a quick patch, but kept getting preempted. Feel free to submit a fix for this, otherwise, I'll try to find time later this week. Thanks, Ezequiel