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=-13.7 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 69EB3C43460 for ; Wed, 28 Apr 2021 14:14:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 361B0613FA for ; Wed, 28 Apr 2021 14:14:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240204AbhD1OPm (ORCPT ); Wed, 28 Apr 2021 10:15:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58850 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239223AbhD1OPk (ORCPT ); Wed, 28 Apr 2021 10:15:40 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62B39C061573; Wed, 28 Apr 2021 07:14:55 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: ezequiel) with ESMTPSA id B54DD1F42AFA Message-ID: Subject: Re: [PATCH v3 79/79] media: hantro: document the usage of pm_runtime_get_sync() From: Ezequiel Garcia To: Mauro Carvalho Chehab Cc: Robin Murphy , 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: Wed, 28 Apr 2021 11:14:44 -0300 In-Reply-To: <20210428084431.0c2d505b@coco.lan> References: <230f22170db7fa57b49cff4570cef15bf11b2ad5.1619519080.git.mchehab+huawei@kernel.org> <02948673-9572-a570-d28e-03a7208f39e1@arm.com> <95ea572e201545b27ff9f48313f7aaea157d4764.camel@collabora.com> <20210428082742.20d54db1@coco.lan> <20210428084431.0c2d505b@coco.lan> 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 Hi Mauro, On Wed, 2021-04-28 at 08:44 +0200, Mauro Carvalho Chehab wrote: > Em Wed, 28 Apr 2021 08:27:42 +0200 > Mauro Carvalho Chehab escreveu: > > > Em Tue, 27 Apr 2021 12:18:32 -0300 > > Ezequiel Garcia escreveu: > > > > > 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.  > > > > What about doing this instead: > > > > diff --git a/drivers/staging/media/hantro/hantro_drv.c b/drivers/staging/media/hantro/hantro_drv.c > > index 595e82a82728..67de6b15236d 100644 > > --- a/drivers/staging/media/hantro/hantro_drv.c > > +++ b/drivers/staging/media/hantro/hantro_drv.c > > @@ -56,14 +56,12 @@ dma_addr_t hantro_get_ref(struct hantro_ctx *ctx, u64 ts) > >         return hantro_get_dec_buf_addr(ctx, buf); > >  } > >   > > -static void hantro_job_finish(struct hantro_dev *vpu, > > -                             struct hantro_ctx *ctx, > > -                             enum vb2_buffer_state result) > > +static void hantro_job_finish_no_pm(struct hantro_dev *vpu, > > +                                   struct hantro_ctx *ctx, > > +                                   enum vb2_buffer_state result) > >  { > >         struct vb2_v4l2_buffer *src, *dst; > >   > > -       pm_runtime_mark_last_busy(vpu->dev); > > -       pm_runtime_put_autosuspend(vpu->dev); > >         clk_bulk_disable(vpu->variant->num_clocks, vpu->clocks); > >   > >         src = v4l2_m2m_next_src_buf(ctx->fh.m2m_ctx); > > @@ -81,6 +79,16 @@ static void hantro_job_finish(struct hantro_dev *vpu, > >                                          result); > >  } > >   > > +static void hantro_job_finish(struct hantro_dev *vpu, > > +                             struct hantro_ctx *ctx, > > +                             enum vb2_buffer_state result) > > +{ > > +       pm_runtime_mark_last_busy(vpu->dev); > > +       pm_runtime_put_autosuspend(vpu->dev); > > + > > +       hantro_job_finish_no_pm(vpu, ctx, result); > > +} > > + > >  void hantro_irq_done(struct hantro_dev *vpu, > >                      enum vb2_buffer_state result) > >  { > > @@ -152,12 +160,13 @@ static void device_run(void *priv) > >         src = hantro_get_src_buf(ctx); > >         dst = hantro_get_dst_buf(ctx); > >   > > +       ret = pm_runtime_resume_and_get(ctx->dev->dev); > > +       if (ret < 0) > > +               goto err_cancel_job; > > + > >         ret = clk_bulk_enable(ctx->dev->variant->num_clocks, ctx->dev->clocks); > >         if (ret) > >                 goto err_cancel_job; > > -       ret = pm_runtime_get_sync(ctx->dev->dev); > > -       if (ret < 0) > > -               goto err_cancel_job; > >   > >         v4l2_m2m_buf_copy_metadata(src, dst, true); > >   > > @@ -165,7 +174,7 @@ static void device_run(void *priv) > >         return; > >   > >  err_cancel_job: > > -       hantro_job_finish(ctx->dev, ctx, VB2_BUF_STATE_ERROR); > > +       hantro_job_finish_no_pm(ctx->dev, ctx, VB2_BUF_STATE_ERROR); > >  } > >   > >  static struct v4l2_m2m_ops vpu_m2m_ops = { > > > > Thanks, > > Mauro > > Actually, the order at the finish logic should change as well. > Maybe like this: > This one looks good. Thanks! Ezequiel > > static void hantro_job_finish_no_pm(struct hantro_dev *vpu, >                                     struct hantro_ctx *ctx, >                                     enum vb2_buffer_state result) > { >         struct vb2_v4l2_buffer *src, *dst; > >         src = v4l2_m2m_next_src_buf(ctx->fh.m2m_ctx); >         dst = v4l2_m2m_next_dst_buf(ctx->fh.m2m_ctx); > >         if (WARN_ON(!src)) >                 return; >         if (WARN_ON(!dst)) >                 return; > >         src->sequence = ctx->sequence_out++; >         dst->sequence = ctx->sequence_cap++; > >         v4l2_m2m_buf_done_and_job_finish(ctx->dev->m2m_dev, ctx->fh.m2m_ctx, >                                          result); > } > > static void hantro_job_finish(struct hantro_dev *vpu, >                               struct hantro_ctx *ctx, >                               enum vb2_buffer_state result) > { > >         hantro_job_finish_no_pm(vpu, ctx, result); > >         clk_bulk_disable(vpu->variant->num_clocks, vpu->clocks); > >         pm_runtime_mark_last_busy(vpu->dev); >         pm_runtime_put_autosuspend(vpu->dev); > } > > static void device_run(void *priv) > { >         struct hantro_ctx *ctx = priv; >         struct vb2_v4l2_buffer *src, *dst; >         int ret; > >         src = hantro_get_src_buf(ctx); >         dst = hantro_get_dst_buf(ctx); > >         ret = pm_runtime_resume_and_get(ctx->dev->dev); >         if (ret < 0) >                 goto err_cancel_job; > >         ret = clk_bulk_enable(ctx->dev->variant->num_clocks, ctx->dev->clocks); >         if (ret) >                 goto err_cancel_job; > >         v4l2_m2m_buf_copy_metadata(src, dst, true); > >         ctx->codec_ops->run(ctx); >         return; > > err_cancel_job: >         hantro_job_finish_no_pm(ctx->dev, ctx, VB2_BUF_STATE_ERROR); > } > > > > Thanks, > Mauro