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

[Dmitry Baryshkov]

Hi,

On Tue, 21 Sept 2021 at 20:01, <abhinavk at codeaurora.org> wrote:
>
> On 2021-09-21 09:22, Dmitry Baryshkov wrote:
> > 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.
> >
> > Fixes: a689554ba6ed ("drm/msm: Initial add DSI connector support")
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>
> This is a valid change and we have seen interrupt storms in downstream
> happening
> when like you said the bootloader leaves the DSI host in unknown state.
> Just one question below.
>
> > ---
> >  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;
> > +     }
> > +
> > +
>
> Do you want to move this to msm_dsi_host_enable()?
> So without the controller being enabled it is still in unknown state?

msm_dsi_host_power_on() reconfigures the host registers, so the state
is known at the end of the power_on().

> Also do you want to do this after dsi0 and dsi1 are initialized to
> account for
> dual dsi cases?

I don't think this should matter. The host won't generate 'extra'
interrupts in such case, will it?

>
> >       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