Quoting Feng Tang (2018-05-08 20:03:15) > > On Mon, May 07, 2018 at 05:09:21PM +0200, Daniel Vetter wrote: > > On Mon, May 07, 2018 at 02:33:25PM +0100, Chris Wilson wrote: > > > Quoting Feng Tang (2018-05-07 22:26:34) > > > > Hi Chris, > > > > > > > > Thanks for the prompt review! > > > > > > > > On Mon, May 07, 2018 at 11:40:45AM +0100, Chris Wilson wrote: > > > > > Quoting Feng Tang (2018-05-07 11:36:09) > > > > > > To fulfil the Dell 4K monitor, the dpcd max retries has been bumped > > > > > > from 7 to 32, which may hurt the boot/init time for some platforms, > > > > > > as the 32 retries may take hundreds of ms. > > > > > > > > > > If we need that many retries, so be it. No modparam, the driver just has > > > > > to work. > > > > > > > > I understand your point. The retry numer was originally 7, and worked > > > > fine untill the Dell 4K monitor which changes to 32. According to my test, > > > > each retry will take about 8ms on the A3960 based NUC. > > > > > > > > One of our product need to boot up within a given time limit, this > > > > 32 retries will take about 1/3 of the budget (about 270ms), that's > > > > why I would try to make it a parameter. > > > > > > The essence is that probing whether a monitor is connected should not be > > > blocking boot. If an async probe tries and fails to find a monitor, > > > fine - no one will notice. If it does take 270ms to find a monitor, it > > > turns on 200ms after userspace kicks in, just like any other hotplug. > > > > Yeah, the fix here is to get the probing out of the driver load path, not > > to break the driver for some funky monitors. And definitely not using a > > modparam. > > Hi Chris and Daniel, > > After reading the i915 modeset init code, I did some experiments: > 1. make the intel_modeset_init() function async (here async means > creating a async func wrapper and call async_schedul() for it) > 2. make the intel_setup_outpus()+intel_modeset_setup_hw_state() async You could just set i915_pci_driver.driver.prove_type = PROBE_PREFER_ASYNCHRONOUS for the same result, or set i915.async_probe=1 for testing. However, if it's blocking on async_synchronize_full(), that will be no improvement. So if it is only an existing async_sychronize_full() causing the fbdev config to be waited on before userspace, we need to stop using the async mechanism and just use an ordinary worker and manual flushing. If it's the fbdev probing blocking you, why are you using fbdev? -Chris _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
