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Wed, 4 Sep 2019 11:38:01 +0800 Message-ID: <1567568281.18318.80.camel@mtksdccf07> Subject: Re: [RFC PATCH V2 4/4] platform: mtk-isp: Add Mediatek FD driver From: Jerry-ch Chen To: Tomasz Figa Date: Wed, 4 Sep 2019 11:38:01 +0800 In-Reply-To: References: <1562661672-22439-1-git-send-email-Jerry-Ch.chen@mediatek.com> <1562661672-22439-5-git-send-email-Jerry-Ch.chen@mediatek.com> <20190802082815.GA203993@chromium.org> <1566724680.20680.8.camel@mtksdccf07> <1566957625.20680.33.camel@mtksdccf07> <1567424859.18318.32.camel@mtksdccf07> <1567493081.18318.49.camel@mtksdccf07> <1567511169.18318.65.camel@mtksdccf07> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190903_203816_808167_23C2881F X-CRM114-Status: GOOD ( 35.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "devicetree@vger.kernel.org" , Sean Cheng =?UTF-8?Q?=28=E9=84=AD=E6=98=87=E5=BC=98=29?= , "laurent.pinchart+renesas@ideasonboard.com" , Rynn Wu =?UTF-8?Q?=28=E5=90=B3=E8=82=B2=E6=81=A9=29?= , srv_heupstream , Po-Yang Huang =?UTF-8?Q?=28=E9=BB=83=E6=9F=8F=E9=99=BD=29?= , "mchehab@kernel.org" , "suleiman@chromium.org" , "shik@chromium.org" , Jungo Lin =?UTF-8?Q?=28=E6=9E=97=E6=98=8E=E4=BF=8A=29?= , Sj Huang =?UTF-8?Q?=28=E9=BB=83=E4=BF=A1=E7=92=8B=29?= , "yuzhao@chromium.org" , "linux-mediatek@lists.infradead.org" , "zwisler@chromium.org" , "matthias.bgg@gmail.com" , Christie Yu =?UTF-8?Q?=28=E6=B8=B8=E9=9B=85=E6=83=A0=29?= , Frederic Chen =?UTF-8?Q?=28=E9=99=B3=E4=BF=8A=E5=85=83=29?= , "hans.verkuil@cisco.com" , "linux-arm-kernel@lists.infradead.org" , "linux-media@vger.kernel.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Tomasz, On Tue, 2019-09-03 at 20:05 +0800, Tomasz Figa wrote: > On Tue, Sep 3, 2019 at 8:46 PM Jerry-ch Chen wrote: > > > > Hi Tomasz, > > > > On Tue, 2019-09-03 at 15:04 +0800, Tomasz Figa wrote: > > > On Tue, Sep 3, 2019 at 3:44 PM Jerry-ch Chen wrote: > > > > > > > > On Tue, 2019-09-03 at 13:19 +0800, Tomasz Figa wrote: > > > > > On Mon, Sep 2, 2019 at 8:47 PM Jerry-ch Chen wrote: > > > > > > > > > > > > Hi Tomasz, > > > > > > > > > > > > On Fri, 2019-08-30 at 16:33 +0800, Tomasz Figa wrote: > > > > > > > On Wed, Aug 28, 2019 at 11:00 AM Jerry-ch Chen > > > > > > > wrote: > > > > > > > > > > > > > > > > Hi Tomasz, > > > > > > > > > > > > > > > > On Mon, 2019-08-26 at 14:36 +0800, Tomasz Figa wrote: > > > > > > > > > Hi Jerry, > > > > > > > > > > > > > > > > > > On Sun, Aug 25, 2019 at 6:18 PM Jerry-ch Chen > > > > > > > > > wrote: > > > > > > > > > > > > > > > > > > > > Hi Tomasz, > > > > > > > > > > > > > > > > > > > > On Fri, 2019-08-02 at 16:28 +0800, Tomasz Figa wrote: > > > > > > > > > > > Hi Jerry, > > > > > > > > > > > > > > > > > > > > > > On Tue, Jul 09, 2019 at 04:41:12PM +0800, Jerry-ch Chen wrote: [snip] > > > > > > > > > [snip] > > > > > > > > > > > > > > > > > > > > > +static void mtk_fd_vb2_stop_streaming(struct vb2_queue *vq) > > > > > > > > > > > > +{ > > > > > > > > > > > > + struct mtk_fd_ctx *ctx = vb2_get_drv_priv(vq); > > > > > > > > > > > > + struct vb2_buffer *vb; > > > > > > > > > > > > > > > > > > > > > > How do we guarantee here that the hardware isn't still accessing the buffers > > > > > > > > > > > removed below? > > > > > > > > > > > > > > > > > > > > > Maybe we can check the driver state flag and aborting the unfinished > > > > > > > > > > jobs? > > > > > > > > > > (fd_hw->state == FD_ENQ) > > > > > > > > > > > > > > > > > > > > > > > > > > > > Yes, we need to either cancel or wait for the currently processing > > > > > > > > > job. It depends on hardware capabilities, but cancelling is generally > > > > > > > > > preferred for the lower latency. > > > > > > > > > > > > > > > > > Ok, it the state is ENQ, then we can disable the FD hw by controlling > > > > > > > > the registers. > > > > > > > > > > > > > > > > for example: > > > > > > > > writel(0x0, fd->fd_base + FD_HW_ENABLE); > > > > > > > > writel(0x0, fd->fd_base + FD_INT_EN); > > > > > > > > > > > > > > > > > > > > > > What's exactly the effect of writing 0 to FD_HW_ENABLE? > > > > > > > > > > > > > Sorry, my last reply didn't solve the question, > > > > > > we should implement a mtk_fd_job_abort() for v4l2_m2m_ops(). > > > > > > > > > > > > which is able to readl_poll_timeout_atomic() > > > > > > and check the HW busy bits in the register FD_INT_EN; > > > > > > > > > > > > if they are not cleared until timeout, we could handle the last > > > > > > processing job. > > > > > > Otherwise, the FD irq handler should have handled the last processing > > > > > > job and we could continue the stop_streaming(). > > > > > > > > > > > > For job_abort(): > > > > > > static void mtk_fd_job_abort(void *priv) > > > > > > { > > > > > > struct mtk_fd_ctx *ctx = priv; > > > > > > struct mtk_fd_dev *fd = ctx->fd_dev; > > > > > > u32 val; > > > > > > u32 ret; > > > > > > > > > > > > ret = readl_poll_timeout_atomic(fd->fd_base + MTK_FD_REG_OFFSET_INT_EN, > > > > > > val, > > > > > > (val & MTK_FD_HW_BUSY_MASK) == > > > > > > MTK_FD_HW_STATE_IS_BUSY, > > > > > > USEC_PER_MSEC, MTK_FD_STOP_HW_TIMEOUT); > > > > > > > > > > Hmm, would it be possible to avoid the busy wait by having a > > > > > completion that could be signalled from the interrupt handler? > > > > > > > > > > Best regards, > > > > > Tomasz > > > > > > > > I suppose that would be wakeup a wait queue in the interrupt handler, > > > > the the wait_event_interrupt_timeout() will be used in here and system > > > > suspend e.g. mtk_fd_suspend(). > > > > > > Yes, that should work. > > > > > > > Or do you suggest to wait_event_interrupt_timeout() every frame in the > > > > mtk_fd_ipi_handler()? > > > > > > Nope, we shouldn't need that. > > > > > > > I think maybe the readl_poll_timeout_atomic would be good enough. > > > > > > > > > > Not really. Busy waiting should be avoided as much as possible. What's > > > the point of entering suspend if you end up burning the power by > > > spinning the CPU for some milliseconds? > > > > > Ok, I see, busy waiting is not a good idea, I will use the wait queue > > instead. the job abort will refine as following: > > > > static void mtk_fd_job_abort(void *priv) > > { > > struct mtk_fd_ctx *ctx = priv; > > struct mtk_fd_dev *fd = ctx->fd_dev; > > u32 ret; > > > > ret = wait_event_interruptible_timeout > > (fd->wq, (fd->fd_irq_result & MTK_FD_HW_IRQ_MASK), > > usecs_to_jiffies(50000)); > > if (ret) > > mtk_fd_hw_job_finish(fd, VB2_BUF_STATE_ERROR); > > dev_dbg(fd->dev, "%s, ret:%d\n", __func__, ret); > > > > fd->fd_irq_result = 0; > > } > > > > static struct v4l2_m2m_ops fd_m2m_ops = { > > .device_run = mtk_fd_device_run, > > .job_abort = mtk_fd_job_abort, > > I'm not sure we should be using the functon above as the .job_abort > callback. It's expected to abort the job, but we're just waiting for > it to finish. I think we should just call mtk_fd_job_abort() manually > from .stop_streaming. > Ok, I will fix it. > > }; > > > > and we could use it in suspend. > > static int mtk_fd_suspend(struct device *dev) > > { > > struct mtk_fd_dev *fd = dev_get_drvdata(dev); > > > > if (pm_runtime_suspended(dev)) > > return 0; > > > > if (fd->fd_stream_count) > > mtk_fd_job_abort(fd->ctx); > > > > /* suspend FD HW */ > > writel(0x0, fd->fd_base + MTK_FD_REG_OFFSET_INT_EN); > > writel(0x0, fd->fd_base + MTK_FD_REG_OFFSET_HW_ENABLE); > > clk_disable_unprepare(fd->fd_clk); > > dev_dbg(dev, "%s:disable clock\n", __func__); > > > > return 0; > > } > > > > static irqreturn_t mtk_fd_irq(int irq, void *data) > > { > > struct mtk_fd_dev *fd = (struct mtk_fd_dev *)data; > > > > fd->fd_irq_result = readl(fd->fd_base + MTK_FD_REG_OFFSET_INT_VAL); > > wake_up_interruptible(&fd->wq); > > The wake up should be done at the very end of this function. Otherwise > we end up with m2m framework racing with the mtk_fd_hw_job_finish() > below. > > Also, I'd use a completion here rather than an open coded wait and > wake-up. The driver could reinit_completion() before queuing a job to > the hardware and the IRQ handler would complete(). There would be no > need to store the IRQ flags in driver data anymore. Ok, It will be refined as following: suspend and stop streaming will call mtk_fd_job_abort() static void mtk_fd_job_abort(struct mtk_fd_dev *fd) { u32 ret; ret = wait_for_completion_timeout(&fd->fd_irq_done, msecs_to_jiffies(MTK_FD_HW_TIMEOUT)); if (ret) mtk_fd_hw_job_finish(fd, VB2_BUF_STATE_ERROR); } complete at irq handler static irqreturn_t mtk_fd_irq(int irq, void *data) { struct mtk_fd_dev *fd = (struct mtk_fd_dev *)data; /* must read this register otherwise HW will keep sending irq */ readl(fd->fd_base + MTK_FD_REG_OFFSET_INT_VAL); fd->output->number = readl(fd->fd_base + MTK_FD_REG_OFFSET_RESULT); dev_dbg(fd->dev, "mtk_fd_face_num:%d\n", fd->output->number); pm_runtime_put((fd->dev)); mtk_fd_hw_job_finish(fd, VB2_BUF_STATE_DONE); complete(&fd->fd_irq_done); return IRQ_HANDLED; } and reinit_completion before time before sending a job to HW static int mtk_fd_hw_job_exec(struct mtk_fd_dev *fd, struct fd_enq_param *fd_param) { struct ipi_message fd_ipi_msg; int ret; pm_runtime_get_sync((fd->dev)); reinit_completion(&fd->fd_irq_done); fd_ipi_msg.cmd_id = MTK_FD_IPI_CMD_ENQUEUE; memcpy(&fd_ipi_msg.fd_enq_param, fd_param, sizeof(struct fd_enq_param)); ret = scp_ipi_send(fd->scp_pdev, SCP_IPI_FD_CMD, &fd_ipi_msg, sizeof(fd_ipi_msg), MTK_FD_IPI_SEND_TIMEOUT); if (ret) { pm_runtime_put((fd->dev)); mtk_fd_hw_job_finish(fd, VB2_BUF_STATE_ERROR); return ret; } return 0; } > > > fd->output->number = readl(fd->fd_base + MTK_FD_REG_OFFSET_RESULT); > > dev_dbg(fd->dev, "mtk_fd_face_num:%d\n", fd->output->number); > > > > pm_runtime_put((fd->dev)); > > mtk_fd_hw_job_finish(fd, VB2_BUF_STATE_DONE); > > return IRQ_HANDLED; > > } > > > > > > > > One more thing, for the mtk_fd_video_device_register() > > > > Sorry that I would need to use intermediate variable here since the 80 > > > > columns check. > > > > > > > > function = MEDIA_ENT_F_PROC_VIDEO_STATISTICS; > > > > ret = v4l2_m2m_register_media_controller(m2m_dev, vfd, function); > > > > > > Why not just make it like this: > > > > > > ret = v4l2_m2m_register_media_controller(m2m_dev, > > > MEDIA_ENT_F_PROC_VIDEO_STATISTICS); > > > > > > The above line is aligned using tabs so that its end is as close to > > > the 80 character boundary as possible. > > > > > I tried but the checkpatch script still gave me a check saying align to > > the scope, I will refine as following: > > > > ret = v4l2_m2m_register_media_controller > > (m2m_dev, vfd, MEDIA_ENT_F_PROC_VIDEO_STATISTICS); > > Please ignore that checkpatch warning, it sometimes gives false > positives. The above looks clearly worse and less consistent with > kernel coding style than what I suggested. > Ok, I see, I will fix it. Thanks and best regards, Jerry > Best regards, > Tomasz _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel