[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 01:29:59 UTC 2021
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?
>
>>
>>> >>>> > 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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