[Freedreno] [DPU PATCH v2 1/2] drm/msm/dsi: check video mode engine status before waiting

[Sean Paul]

On Mon, Apr 16, 2018 at 10:44:57AM -0700, abhinavk at codeaurora.org wrote:
> Hi Sean
> 
> Thanks for reviewing.
> 
> Reply inline.
> 
> On 2018-04-16 10:07, Sean Paul wrote:
> > On Fri, Apr 13, 2018 at 03:04:48PM -0700, abhinavk at codeaurora.org wrote:
> > > On 2018-04-13 14:10, abhinavk at codeaurora.org wrote:
> > > > Hi Sean
> > > >
> > > > Thanks for the review.
> > > >
> > > > Reply inline.
> > > >
> > > > On 2018-04-13 13:26, Sean Paul wrote:
> > > > > On Tue, Apr 10, 2018 at 06:54:06PM -0700, Abhinav Kumar wrote:
> > > > > > Make sure the video mode engine is on before waiting
> > > > > > for the video done interrupt.
> > > > > >
> > > > > > Otherwise it leads to silent timeouts increasing display
> > > > > > turn ON time.
> > > > > >
> > > > > > Changes in v2:
> > > > > > - Replace pr_err with dev_err
> > > > > > - Changed error message
> > > > > >
> > > > > > Signed-off-by: Abhinav Kumar <abhinavk at codeaurora.org>
> > > > > > ---
> > > > > >  drivers/gpu/drm/msm/dsi/dsi_host.c | 15 +++++++++++----
> > > > > >  1 file changed, 11 insertions(+), 4 deletions(-)
> > > > > >
> > > > > > diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c
> > > > > > b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > > > > > index 7a03a94..5b7b290 100644
> > > > > > --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> > > > > > +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > > > > > @@ -173,6 +173,7 @@ struct msm_dsi_host {
> > > > > >
> > > > > >  	bool registered;
> > > > > >  	bool power_on;
> > > > > > +	bool enabled;
> > > > > >  	int irq;
> > > > > >  };
> > > > > >
> > > > > > @@ -986,13 +987,19 @@ static void dsi_set_tx_power_mode(int
> > > > > > mode, struct msm_dsi_host *msm_host)
> > > > > >
> > > > > >  static void dsi_wait4video_done(struct msm_dsi_host *msm_host)
> > > > > >  {
> > > > > > +	u32 ret = 0;
> > > > > > +	struct device *dev = &msm_host->pdev->dev;
> > > > > > +
> > > > > >  	dsi_intr_ctrl(msm_host, DSI_IRQ_MASK_VIDEO_DONE, 1);
> > > > > >
> > > > > >  	reinit_completion(&msm_host->video_comp);
> > > > > >
> > > > > > -	wait_for_completion_timeout(&msm_host->video_comp,
> > > > > > +	ret = wait_for_completion_timeout(&msm_host->video_comp,
> > > > > >  			msecs_to_jiffies(70));
> > > > > >
> > > > > > +	if (ret <= 0)
> > > > > > +		dev_err(dev, "wait for video done timed out\n");
> > > > > > +
> > > > > >  	dsi_intr_ctrl(msm_host, DSI_IRQ_MASK_VIDEO_DONE, 0);
> > > > > >  }
> > > > > >
> > > > > > @@ -1001,7 +1008,7 @@ static void dsi_wait4video_eng_busy(struct
> > > > > > msm_dsi_host *msm_host)
> > > > > >  	if (!(msm_host->mode_flags & MIPI_DSI_MODE_VIDEO))
> > > > > >  		return;
> > > > > >
> > > > > > -	if (msm_host->power_on) {
> > > > > > +	if (msm_host->power_on && msm_host->enabled) {
> > > > > >  		dsi_wait4video_done(msm_host);
> > > > > >  		/* delay 4 ms to skip BLLP */
> > > > > >  		usleep_range(2000, 4000);
> > > > > > @@ -2203,7 +2210,7 @@ int msm_dsi_host_enable(struct
> > > > > > mipi_dsi_host *host)
> > > > > >  	 *	pm_runtime_put_autosuspend(&msm_host->pdev->dev);
> > > > > >  	 * }
> > > > > >  	 */
> > > > > > -
> > > > > > +	msm_host->enabled = true;
> > > > > >  	return 0;
> > > > > >  }
> > > > > >
> > > > > > @@ -2219,7 +2226,7 @@ int msm_dsi_host_disable(struct
> > > > > > mipi_dsi_host *host)
> > > > > >  	 * Reset to disable video engine so that we can send off cmd.
> > > > > >  	 */
> > > > > >  	dsi_sw_reset(msm_host);
> > > > > > -
> > > > > > +	msm_host->enabled = false;
> > > > >
> > > > > This should go at the start of the function. Also, it's unclear from
> > > > > this patch,
> > > > > but I assume this is protected by a lock?
> > > > >
> > > > > Sean
> > > > [Abhinav] Yes, will move this to the start.
> > > > No, there is no lock here but at this point doesnt need one.
> > > > The reason is that, this variable will be written to and read by the
> > > > same process
> > > > (suspend thread OR resume thread which sends the panel ON/OFF commands).
> > > > If we decide to expose other interfaces to send commands like debugfs
> > > > or sysfs and
> > > > introduce more threads, we will add the locking.
> > > [Abhinav] Correction to my prev comment, we do have the
> > > msm_host->cmd_mutex
> > > which will
> > > ensure this entire process is protected. That should suffice.
> > 
> > Ok, thanks for confirming. Could you also please split this patch into
> > the
> > wait4video_done ret fix and the ->enabled addition? The 2 seem mostly
> > unrelated.
> > 
> > Sean
> 
> They are quite related actually. So we were not able to catch this earlier
> because the wait was silently timing out. Hence along with the fix I wanted
> to change the ret to add the error log because such condition should not
> happen with the ->enabled fix. To signify that I clubbed them together.
> I can split them, if this still feels unrelated.

Thanks for the explanation, they're unrelated in the sense that you're fixing 2
things in this patch. The first fix is to not fail silently, and the second fix
is to ensure the engine is on before waiting for the interrupt. So IMO, this is
2 patches.

Sean

> 
> > > > >
> > > > >
> > > > > >  	return 0;
> > > > > >  }
> > > > > >
> > > > > > --
> > > > > > The Qualcomm Innovation Center, Inc. is a member of the Code
> > > > > > Aurora Forum,
> > > > > > a Linux Foundation Collaborative Project
> > > > > >
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-- 
Sean Paul, Software Engineer, Google / Chromium OS