[Freedreno] [PATCH] drm/msm/dsi: do not install irq handler before power up the host
Dmitry Baryshkov
dmitry.baryshkov at linaro.org
Tue Sep 28 01:40:30 UTC 2021
On 28/09/2021 04:33, abhinavk at codeaurora.org wrote:
> On 2021-09-27 18:29, Dmitry Baryshkov wrote:
>> On 28/09/2021 04:19, abhinavk at codeaurora.org wrote:
>>> On 2021-09-27 18:06, Dmitry Baryshkov wrote:
>>>> On Tue, 28 Sept 2021 at 03:22, <abhinavk at codeaurora.org> wrote:
>>>>>
>>>>> On 2021-09-25 12:43, Dmitry Baryshkov wrote:
>>>>> > On 21/09/2021 23:52, abhinavk at codeaurora.org wrote:
>>>>> >> On 2021-09-21 10:47, Dmitry Baryshkov wrote:
>>>>> >>> 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?
>>>>> >>>
>>>>> >> 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.
Ah. Then it would be better to call it between power_on() and enable().
I'll send v3.
>
>>
>>>
>>>>
>>>>> >>>> > 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
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