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

[abhinavk@codeaurora.org]

On 2021-09-25 12:43, Dmitry Baryshkov wrote:
> On 21/09/2021 23:52, abhinavk@codeaurora.org wrote:
>> On 2021-09-21 10:47, Dmitry Baryshkov wrote:
>>> Hi,
>>> 
>>> On Tue, 21 Sept 2021 at 20:01, <abhinavk@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@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?
>>> 
>> We have seen cases where misconfiguration has caused interrupts to 
>> storm only
>> on one DSI in some cases. So yes, I would prefer this is done after 
>> both are
>> configured.
> 
> I've checked. The power_on is called from dsi_mgr_bridge_pre_enable()
> when both DSI hosts should be bound.

DSI being bound is enough? I thought the issue we are trying to address 
is that
we need to have called msm_dsi_host_power_on() for both the hosts so 
that both are
put in the known state before requesting the irq.

OR in other words move the irq_enable() to below location.

341 static void dsi_mgr_bridge_pre_enable(struct drm_bridge *bridge)
342 {
********************************
364 	ret = msm_dsi_host_power_on(host, &phy_shared_timings[id], 
is_bonded_dsi, msm_dsi->phy);
365 	if (ret) {
366 		pr_err("%s: power on host %d failed, %d\n", __func__, id, ret);
367 		goto host_on_fail;
368 	}
369
370 	if (is_bonded_dsi && msm_dsi1) {
371 		ret = msm_dsi_host_power_on(msm_dsi1->host,
372 				&phy_shared_timings[DSI_1], is_bonded_dsi, msm_dsi1->phy);
373 		if (ret) {
374 			pr_err("%s: power on host1 failed, %d\n",
375 							__func__, ret);
376 			goto host1_on_fail;
377 		}
378 	}

< move the irq enable here >
**********************************

> 
>> 
>>>> 
>>>> >       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)