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Imre Deak
f7d16a538a
If an HPD IRQ storm is detected on a connector during driver loading or
system suspend/resume - disabling the IRQ and switching to polling - the
polling may get disabled too early - before the intended 2 minute
HPD_STORM_REENABLE_DELAY - with the HPD IRQ staying disabled for this
duration. One such sequence is:
Thread#1 Thread#2
intel_display_driver_probe()->
intel_hpd_init()->
(HPD IRQ gets enabled)
. intel_hpd_irq_handler()->
. intel_hpd_irq_storm_detect()
. intel_hpd_irq_setup()->
. (HPD IRQ gets disabled)
. queue_delayed_work(hotplug.hotplug_work)
. ...
. i915_hotplug_work_func()->
. intel_hpd_irq_storm_switch_to_polling()->
. (polling enabled)
.
intel_hpd_poll_disable()->
queue_work(hotplug.poll_init_work)
...
i915_hpd_poll_init_work()->
(polling gets disabled,
HPD IRQ is still disabled)
...
(Connector is neither polled or
detected via HPD IRQs for 2 minutes)
intel_hpd_irq_storm_reenable_work()->
(HPD IRQ gets enabled)
To avoid the above 2 minute state without either polling or enabled HPD
IRQ, leave the connector's polling mode unchanged in
i915_hpd_poll_init_work() if its HPD IRQ got disabled after an IRQ storm
indicated by the connector's HPD_DISABLED pin state.
Link: https://patchwork.freedesktop.org/patch/msgid/20240104083008.2715733-3-imre.deak@intel.com
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.