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. > > > This patch makes no functional change, but make the max retries > > adjustable, so that concerned users/platforms can have an option > > to short the wait time. > > > > On a Intel Atom Processor A3960 based NUC, the i915_init() time could > > be reduced from 450ms to 200ms. > > > > retries = 3: > > [ 0.457806] calling i915_init+0x0/0x51 @ 1 > > [ 0.662307] initcall i915_init+0x0/0x51 returned 0 after 199694 usecs > > > > retries = 32: > > [ 0.465818] calling i915_init+0x0/0x51 @ 1 > > [ 0.925831] initcall i915_init+0x0/0x51 returned 0 after 449219 usecs > > Why is this synchronous anyway? I don't know the reason, maybe some of kernel components depends on the GFX module. But even we can put it to async, it is still the longest init one on our platform. Thanks, Feng _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
