Messages in this thread | | | Date | Sat, 4 Mar 2023 01:38:22 +0200 | Subject | Re: [PATCH v3] drm/msm/dp: check core_initialized flag at both host_init() and host_deinit() | From | Dmitry Baryshkov <> |
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On 04/03/2023 00:45, Kuogee Hsieh wrote: > > On 3/2/2023 11:04 AM, Dmitry Baryshkov wrote: >> On Thu, 2 Mar 2023 at 20:41, Kuogee Hsieh <quic_khsieh@quicinc.com> >> wrote: >>> >>> On 3/1/2023 1:15 PM, Dmitry Baryshkov wrote: >>>> On 01/03/2023 18:57, Kuogee Hsieh wrote: >>>>> On 2/28/2023 6:16 PM, Dmitry Baryshkov wrote: >>>>>> On Wed, 1 Mar 2023 at 02:17, Kuogee Hsieh <quic_khsieh@quicinc.com> >>>>>> wrote: >>>>>>> There is a reboot/suspend test case where system suspend is forced >>>>>>> during system booting up. Since dp_display_host_init() of external >>>>>>> DP is executed at hpd thread context, this test case may created a >>>>>>> scenario that dp_display_host_deinit() from pm_suspend() run before >>>>>>> dp_display_host_init() if hpd thread has no chance to run during >>>>>>> booting up while suspend request command was issued. At this >>>>>>> scenario >>>>>>> system will crash at aux register access at dp_display_host_deinit() >>>>>>> since aux clock had not yet been enabled by dp_display_host_init(). >>>>>>> Therefore we have to ensure aux clock enabled by checking >>>>>>> core_initialized flag before access aux registers at pm_suspend. >>>>>> Can a call to dp_display_host_init() be moved from >>>>>> dp_display_config_hpd() to dp_display_bind()? >>>>> yes, Sankeerth's "drm/msm/dp: enable pm_runtime support for dp >>>>> driver" patch is doing that which is under review. >>>>> >>>>> https://patchwork.freedesktop.org/patch/523879/?series=114297&rev=1 >>>> No, he is doing another thing. He is moving these calls to pm_runtime >>>> callbacks, not to the dp_display_bind(). >>>> >>>>>> Related question: what is the primary reason for having >>>>>> EV_HPD_INIT_SETUP and calling dp_display_config_hpd() via the event >>>>>> thread? Does DP driver really depend on DPU irqs being installed? As >>>>>> far as I understand, DP device uses MDSS interrupts and those IRQs >>>>>> are >>>>>> available and working at the time of dp_display_probe() / >>>>>> dp_display_bind(). >>>>> HDP gpio pin has to run through DP aux module 100ms denouncing logic >>>>> and have its mask bits. >>>>> >>>>> Therefore DP irq has to be enabled to receive DP isr with mask bits >>>>> set. >>>> So... DP irq is enabled by the MDSS, not by the DPU. Again, why does >>>> DP driver depend on DPU irqs being installed? >>> sorry, previously i mis understand your question -- why does DP driver >>> depend on DPU irqs being installed? >>> >>> now, I think you are asking why dpu_irq_postinstall() ==> >>> msm_dp_irq_postinstall() ==> event_thread ==> dp_display_config_hdp() >>> ==> enable_irq(dp->irq) >>> >>> With the below test i had run, i think the reason is to make sure >>> dp->irq be requested before enable it. >>> >>> I just run the execution timing order test and collect execution order >>> as descending order at below, >>> >>> 1) dp_display_probe() -- start >>> >>> 2) dp_display_bind() >>> >>> 3) msm_dp_modeset_init() ==> dp_display_request_irq() ==> >>> dp_display_get_next_bridge() >>> >>> 4) dpu_irq_postinstall() ==> msm_dp_irq_postinstall() ==> >>> enable_irq(dp->irq) >>> >>> 5) dp_display_probe() -- end >>> >>> dp->irq is request at msm_dp_modeset_init() and enabled after. >> Should be moved to probe. >> >>> That bring up the issue to move DP's dp_display_host_init() executed at >>> dp_display_bind(). >>> >>> Since eDP have dp_dispaly_host_init() executed at >>> dp_display_get_next_bridge() which executed after dp_display_bind(). >>> >>> If moved DP's dp_display_host_init() to dp_dispaly_bind() which means DP >>> will be ready to receive HPD irq before eDP ready. >> And the AUX bus population should also be moved to probe(), which >> means we should call dp_display_host_init() from probe() too. >> Having aux_bus_populate in probe would allow moving component_add() to >> the done_probing() callback, making probe/defer case more robust >> >>> This may create some uncertainties at execution flow and complicate >>> things up. >> Hopefully the changes suggested above will make it simpler. > > ok, I will create another patch to
patchset
> > 1) move dp_display_host_init() to probe() > > 2) move component_add() to done_probing() for eDP > > 3) keep DP as simple platform device (component_add() still executed in > probe())
4) move devm_request_irq() to probe, add IRQF_NO_AUTOEN instead of calling disable_irq() right after request_irq()
5) drop DP_HPD_INIT_SETUP and related code
> > Meanwhile, can you approve this patch so that it will not block our > internal daily testing?
Quoting your commit message: "Since dp_display_host_init() of external DP is executed at hpd thread context...". After these changes the mentioned function will no longer be executed from the hpd thread. So, let's rework the probe/init sequence first, then we can see if this patch is still necessary and how should it look.
-- With best wishes Dmitry
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