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 >
**********************************
