From: Tomasz Figa <tfiga@chromium.org>
To: Jerry-ch Chen <Jerry-ch.Chen@mediatek.com>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"Sean Cheng (鄭昇弘)" <Sean.Cheng@mediatek.com>,
"laurent.pinchart+renesas@ideasonboard.com"
<laurent.pinchart+renesas@ideasonboard.com>,
"Rynn Wu (吳育恩)" <Rynn.Wu@mediatek.com>,
srv_heupstream <srv_heupstream@mediatek.com>,
"Po-Yang Huang (黃柏陽)" <po-yang.huang@mediatek.com>,
"mchehab@kernel.org" <mchehab@kernel.org>,
"suleiman@chromium.org" <suleiman@chromium.org>,
"shik@chromium.org" <shik@chromium.org>,
"Jungo Lin (林明俊)" <jungo.lin@mediatek.com>,
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<linux-mediatek@lists.infradead.org>,
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"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
"Christie Yu (游雅惠)" <christie.yu@mediatek.com>,
"Frederic Chen (陳俊元)" <Frederic.Chen@mediatek.com>,
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"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>
Subject: Re: [RFC PATCH V2 4/4] platform: mtk-isp: Add Mediatek FD driver
Date: Wed, 4 Sep 2019 15:34:49 +0900 [thread overview]
Message-ID: <CAAFQd5AxTQPD+nP9CJs45QTzGHKssjv3vRtMqHONABfp12afYw@mail.gmail.com> (raw)
In-Reply-To: <1567577389.18318.100.camel@mtksdccf07>
On Wed, Sep 4, 2019 at 3:09 PM Jerry-ch Chen <Jerry-ch.Chen@mediatek.com> wrote:
>
> Hi Tomasz,
>
> On Wed, 2019-09-04 at 12:15 +0800, Tomasz Figa wrote:
> > On Wed, Sep 4, 2019 at 12:38 PM Jerry-ch Chen
> > <Jerry-ch.Chen@mediatek.com> wrote:
> > >
> > > 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 <Jerry-ch.Chen@mediatek.com> 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 <Jerry-ch.Chen@mediatek.com> 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 <Jerry-ch.Chen@mediatek.com> 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
> > > > > > > > > > <Jerry-ch.Chen@mediatek.com> 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
> > > > > > > > > > > > <Jerry-ch.Chen@mediatek.com> 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)
> >
> > For the _timeout variants, !ret means the timeout and ret > 0 means
> > that the wait ended successfully before.
> >
> Thanks, fixed.
>
> > Also please make sure that the timeout is big enough not to happen
> > normally on a heavily loaded system. Something like 1 second should be
> > good.
> >
> Ok, I will make it 1 second
> #define MTK_FD_HW_TIMEOUT 1000
>
> Also, I will add a condition in mtk_fd_vb2_stop_streaming(), since it
> would be called twice, now it works fine whether I reuse the condition
> with mtk_fd_hw_disconnect or not, however, I think do it before buffer
> remove looks more reasonable.
>
> static void mtk_fd_vb2_stop_streaming(struct vb2_queue *vq)
> {
> struct mtk_fd_ctx *ctx = vb2_get_drv_priv(vq);
> struct mtk_fd_dev *fd = ctx->fd_dev;
> struct vb2_v4l2_buffer *vb;
> struct v4l2_m2m_ctx *m2m_ctx = ctx->fh.m2m_ctx;
> struct v4l2_m2m_queue_ctx *queue_ctx;
>
> if (vq->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
> mtk_fd_job_abort(fd);
We need to do it regardless of the queue type, otherwise we could
still free CAPTURE buffers before the hardware releases them.
Best regards,
Tomasz
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next prev parent reply other threads:[~2019-09-04 6:40 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-09 8:41 [RFC PATCH V2 0/4] media: platform: Add support for Face Detection (FD) on mt8183 SoC Jerry-ch Chen
2019-07-09 8:41 ` [RFC PATCH V2 1/4] dt-bindings: mt8183: Added FD dt-bindings Jerry-ch Chen
2019-07-12 7:16 ` CK Hu
2019-07-09 8:41 ` [RFC PATCH V2 2/4] dts: arm64: mt8183: Add FD nodes Jerry-ch Chen
2019-07-09 8:41 ` [RFC PATCH V2 3/4] media: platform: Add Mediatek FD driver KConfig Jerry-ch Chen
2019-09-05 12:30 ` Laurent Pinchart
2019-09-05 14:14 ` Jerry-ch Chen
2019-07-09 8:41 ` [RFC PATCH V2 4/4] platform: mtk-isp: Add Mediatek FD driver Jerry-ch Chen
2019-07-09 10:56 ` Enrico Weigelt, metux IT consult
2019-07-29 6:01 ` Jerry-ch Chen
2019-07-29 9:57 ` Tomasz Figa
2019-07-29 11:58 ` Jerry-ch Chen
2019-08-09 8:07 ` Tomasz Figa
2019-09-05 12:35 ` Laurent Pinchart
2019-08-02 8:28 ` Tomasz Figa
2019-08-25 9:18 ` Jerry-ch Chen
2019-08-26 6:36 ` Tomasz Figa
2019-08-28 2:00 ` Jerry-ch Chen
2019-08-30 8:33 ` Tomasz Figa
2019-09-02 11:47 ` Jerry-ch Chen
2019-09-03 5:19 ` Tomasz Figa
2019-09-03 6:44 ` Jerry-ch Chen
2019-09-03 7:04 ` Tomasz Figa
2019-09-03 11:46 ` Jerry-ch Chen
2019-09-03 12:05 ` Tomasz Figa
2019-09-04 3:38 ` Jerry-ch Chen
2019-09-04 4:15 ` Tomasz Figa
2019-09-04 6:09 ` Jerry-ch Chen
2019-09-04 6:34 ` Tomasz Figa [this message]
2019-09-04 8:09 ` Jerry-ch Chen
2019-09-04 8:25 ` Tomasz Figa
2019-09-04 9:01 ` Jerry-ch Chen
2019-09-04 9:03 ` Tomasz Figa
2019-09-04 9:26 ` Jerry-ch Chen
2019-09-04 13:12 ` Tomasz Figa
2019-09-04 13:19 ` Jerry-ch Chen
2019-09-05 7:02 ` Jerry-ch Chen
2019-09-05 7:13 ` Tomasz Figa
2019-09-05 8:16 ` Jerry-ch Chen
2019-09-05 8:52 ` Tomasz Figa
2019-09-05 13:36 ` Jerry-ch Chen
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