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

[abhinavk@codeaurora.org]

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