On Fri, May 17, 2019 at 10:14:18AM +0200, Torsten Duwe wrote: > On Fri, 17 May 2019 09:27:38 +0200 > Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > > > On Thu, May 16, 2019 at 06:48:59PM +0200, Torsten Duwe wrote: > > > On Thu, May 16, 2019 at 09:06:41AM -0700, Vasily Khoruzhick wrote: > > > > > > > > Driver can talk to the panel over AUX channel only after t1+t3, > > > > t1 is up to 10ms, t3 is up to 200ms. > > > > > > This is after power-on. The boot loader needs to deal with this. > > > > The bootloader can deal with it, but the kernel will also need to. The > > bootloader might not be doing this because it's not been updated, the > > regulator might have been disabled between the time the kernel was > > started and the time the bridge driver probes, etc. > > No, you cannot practically switch off this voltage. It supports _all_ > the devices I mentioned. In fact, the PMIC needs to enable it initially, > and then it takes some time before the SoC can access the MMC and read > the SPL from it, just because of exactly these 3.3V. Then the boot > loader starts, and later the eDP bridge gets initialised. All these devices can be unused, disabled, or compiled as modules. > In *theory*, albeit a very daring one, I could imagine a very deep > sleep mode that can only be ended by pressing the power button, which > should still work without DCDC1. Only then, a description of the panel > would be required. But I probably missed something and even this does > not work. > > So for all current practical purposes, we can assume the Teres-I panel > to be powered properly and providing valid EDID; nothing to worry about > in software. You're creating a generic binding for all the users of that bridge, while considering only the specific case of the Teres-I. Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
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