Re: [PATCH] drm/msm/dsi: do not install irq handler before power up the host

[Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>]

On 21/09/2021 21:26, Andrzej Hajda wrote:
> W dniu 21.09.2021 o 18:22, Dmitry Baryshkov pisze:
> > The DSI host might be left in some state by the bootloader. If this
> > state generates an IRQ, it might hang the system by holding the
> > interrupt line before the driver sets up the DSI host to the known
> > state.
> >
> > Move the request/free_irq calls into msm_dsi_host_power_on/_off calls,
> > so that we can be sure that the interrupt is delivered when the host is
> > in the known state.
>
>
> The established practice is to request IRQ in probe, to avoid
> auto-enabling use IRQF_NO_AUTOEN flag.
>
> Then you can call enable_irq in power-on.

Nice idea, thank you! I somehow missed addition of IRQF_NO_AUTOEN. I've 
used it in v2 ([PATCH v2] drm/msm/dsi: do not enable irq handler before 
powering up the host).

> Regards
>
> Andrzej
>
>
>
> > Fixes: a689554ba6ed ("drm/msm: Initial add DSI connector support")
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > ---
> >    drivers/gpu/drm/msm/dsi/dsi_host.c | 21 ++++++++++++---------
> >    1 file changed, 12 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > index e269df285136..cd842347a6b1 100644
> > --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> > +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > @@ -1951,15 +1951,6 @@ int msm_dsi_host_modeset_init(struct mipi_dsi_host *host,
> >    		return ret;
> >    	}
> >    
> > -	ret = devm_request_irq(&pdev->dev, msm_host->irq,
> > -			dsi_host_irq, IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
> > -			"dsi_isr", msm_host);
> > -	if (ret < 0) {
> > -		DRM_DEV_ERROR(&pdev->dev, "failed to request IRQ%u: %d\n",
> > -				msm_host->irq, ret);
> > -		return ret;
> > -	}
> > -
> >    	msm_host->dev = dev;
> >    	ret = cfg_hnd->ops->tx_buf_alloc(msm_host, SZ_4K);
> >    	if (ret) {
> > @@ -2413,6 +2404,16 @@ int msm_dsi_host_power_on(struct mipi_dsi_host *host,
> >    	if (msm_host->disp_en_gpio)
> >    		gpiod_set_value(msm_host->disp_en_gpio, 1);
> >    
> > +	ret = devm_request_irq(&msm_host->pdev->dev, msm_host->irq,
> > +			dsi_host_irq, IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
> > +			"dsi_isr", msm_host);
> > +	if (ret < 0) {
> > +		DRM_DEV_ERROR(&msm_host->pdev->dev, "failed to request IRQ%u: %d\n",
> > +				msm_host->irq, ret);
> > +		return ret;
> > +	}
> > +
> > +
> >    	msm_host->power_on = true;
> >    	mutex_unlock(&msm_host->dev_mutex);
> >    
> > @@ -2439,6 +2440,8 @@ int msm_dsi_host_power_off(struct mipi_dsi_host *host)
> >    		goto unlock_ret;
> >    	}
> >    
> > +	devm_free_irq(&msm_host->pdev->dev, msm_host->irq, msm_host);
> > +
> >    	dsi_ctrl_config(msm_host, false, NULL, NULL);
> >    
> >    	if (msm_host->disp_en_gpio)


--
With best wishes
Dmitry