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

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On 2021-09-27 18:29, Dmitry Baryshkov wrote:
On 28/09/2021 04:19, abhinavk@xxxxxxxxxxxxxx wrote:
On 2021-09-27 18:06, Dmitry Baryshkov wrote:
On Tue, 28 Sept 2021 at 03:22, <abhinavk@xxxxxxxxxxxxxx> wrote:

On 2021-09-25 12:43, Dmitry Baryshkov wrote:
> On 21/09/2021 23:52, abhinavk@xxxxxxxxxxxxxx wrote:
>> On 2021-09-21 10:47, Dmitry Baryshkov wrote:
>>> Hi,
>>>
>>> On Tue, 21 Sept 2021 at 20:01, <abhinavk@xxxxxxxxxxxxxx> 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@xxxxxxxxxx>
>>>>
>>>> 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 >
**********************************

Ah, I see your point. What about moving to msm_dsi_host_enable() then?

Yes, I had suggested this a few replies ago. But only at the dsi_msgr we know if DSI1 is also done.
So you can do it right after it in below location?

427     if (is_dual_dsi && msm_dsi1) {
428         ret = msm_dsi_host_enable(msm_dsi1->host);
429         if (ret) {
430             pr_err("%s: enable host1 failed, %d\n", __func__, ret);
431             goto host1_en_fail;
432         }
433     }

<enable_irq here? >

If there is DSI1, it was also powered on/programmed at the time of
msm_dsi_host_enable, so enabling IRQs from it should be safe. Do you
see any pitfalls from enabling the irq from that function?

Just about symmetry. We will enable_irq() for DSI0 when DSI0 and DSI1 are powered on
But for DSI1, we will enable it when its powered ON but not enabled.
Hence i thought its better this way.




>>>> >       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)



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