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[35.190.215.205]) by smtp.gmail.com with ESMTPSA id j190sm7073152wmb.33.2020.05.21.08.22.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 May 2020 08:22:54 -0700 (PDT) Date: Thu, 21 May 2020 15:22:53 +0000 From: Tomasz Figa To: Xia Jiang Cc: Hans Verkuil , Mauro Carvalho Chehab , Rob Herring , Matthias Brugger , Rick Chang , linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, Marek Szyprowski , srv_heupstream@mediatek.com, senozhatsky@chromium.org, mojahsu@chromium.org, drinkcat@chromium.org, maoguang.meng@mediatek.com, sj.huang@mediatek.com Subject: Re: [PATCH v8 05/14] media: platform: Improve power on and power off flow Message-ID: <20200521152253.GE209565@chromium.org> References: <20200403094033.8288-1-xia.jiang@mediatek.com> <20200403094033.8288-6-xia.jiang@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200403094033.8288-6-xia.jiang@mediatek.com> Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Xia, On Fri, Apr 03, 2020 at 05:40:24PM +0800, Xia Jiang wrote: > Call pm_runtime_get_sync() before starting a frame and then > pm_runtime_put() after completing it. This can save power for the time > between processing two frames. > > Signed-off-by: Xia Jiang > --- > .../media/platform/mtk-jpeg/mtk_jpeg_core.c | 27 +++++-------------- > 1 file changed, 6 insertions(+), 21 deletions(-) > Thank you for the patch. Please see my comments inline. > diff --git a/drivers/media/platform/mtk-jpeg/mtk_jpeg_core.c b/drivers/media/platform/mtk-jpeg/mtk_jpeg_core.c > index a536fa95b3d6..dd5cadd101ef 100644 > --- a/drivers/media/platform/mtk-jpeg/mtk_jpeg_core.c > +++ b/drivers/media/platform/mtk-jpeg/mtk_jpeg_core.c > @@ -710,23 +710,6 @@ static struct vb2_v4l2_buffer *mtk_jpeg_buf_remove(struct mtk_jpeg_ctx *ctx, > return v4l2_m2m_dst_buf_remove(ctx->fh.m2m_ctx); > } > > -static int mtk_jpeg_start_streaming(struct vb2_queue *q, unsigned int count) > -{ > - struct mtk_jpeg_ctx *ctx = vb2_get_drv_priv(q); > - struct vb2_v4l2_buffer *vb; > - int ret = 0; > - > - ret = pm_runtime_get_sync(ctx->jpeg->dev); > - if (ret < 0) > - goto err; > - > - return 0; > -err: > - while ((vb = mtk_jpeg_buf_remove(ctx, q->type))) > - v4l2_m2m_buf_done(vb, VB2_BUF_STATE_QUEUED); > - return ret; > -} > - > static void mtk_jpeg_stop_streaming(struct vb2_queue *q) > { > struct mtk_jpeg_ctx *ctx = vb2_get_drv_priv(q); > @@ -751,8 +734,6 @@ static void mtk_jpeg_stop_streaming(struct vb2_queue *q) > > while ((vb = mtk_jpeg_buf_remove(ctx, q->type))) > v4l2_m2m_buf_done(vb, VB2_BUF_STATE_ERROR); > - > - pm_runtime_put_sync(ctx->jpeg->dev); > } > > static const struct vb2_ops mtk_jpeg_qops = { > @@ -761,7 +742,6 @@ static const struct vb2_ops mtk_jpeg_qops = { > .buf_queue = mtk_jpeg_buf_queue, > .wait_prepare = vb2_ops_wait_prepare, > .wait_finish = vb2_ops_wait_finish, > - .start_streaming = mtk_jpeg_start_streaming, > .stop_streaming = mtk_jpeg_stop_streaming, > }; > > @@ -812,7 +792,7 @@ static void mtk_jpeg_device_run(void *priv) > struct mtk_jpeg_src_buf *jpeg_src_buf; > struct mtk_jpeg_bs bs; > struct mtk_jpeg_fb fb; > - int i; > + int i, ret; > > src_buf = v4l2_m2m_next_src_buf(ctx->fh.m2m_ctx); > dst_buf = v4l2_m2m_next_dst_buf(ctx->fh.m2m_ctx); > @@ -832,6 +812,10 @@ static void mtk_jpeg_device_run(void *priv) > return; > } > > + ret = pm_runtime_get_sync(jpeg->dev); > + if (ret < 0) > + goto dec_end; > + > mtk_jpeg_set_dec_src(ctx, &src_buf->vb2_buf, &bs); > if (mtk_jpeg_set_dec_dst(ctx, &jpeg_src_buf->dec_param, &dst_buf->vb2_buf, &fb)) > goto dec_end; > @@ -957,6 +941,7 @@ static irqreturn_t mtk_jpeg_dec_irq(int irq, void *priv) > v4l2_m2m_buf_done(src_buf, buf_state); > v4l2_m2m_buf_done(dst_buf, buf_state); > v4l2_m2m_job_finish(jpeg->m2m_dev, ctx->fh.m2m_ctx); > + pm_runtime_put_sync(ctx->jpeg->dev); The _sync variant explicitly waits until the asynchronous PM operation completes. This is usually undesired, because the CPU stays blocked for no good reason. In this context it is actually a bug, because this is an interrupt handler and it's not allowed to sleep. I wonder why this actually didn't crash in your testing. Please change to the regular pm_runtime_put(). Best regards, Tomasz