Hi Igor,
my two cents from previous experience:
On 06.07.20 10:34, Igor Opaniuk wrote:
Hi,
Does anyone have experience in setting up seamless boot splash on iMX-based platforms?
I'm currently trying to do that on iMX7-based board with 4.9 2.3.x IMX downstream kernel running.
Well, i.MX7 have a chance because it has no GPU. I did this for TI based boards, too.
But let me say that it is tricky and it creates big dependencies between U-Boot and kernel. And to get a flicker-free images, the clock setup should be exactly the same between U-Boot and kernel, and this is not often (or never) the same because we need a lot of more features (layers, overlays, ..) in kernel, while we just to need to show something like a logo in U-Boot.
With the introduction of DRM, things are more difficult. Take also into account that a small change in kernel can be enough to have a weird transition on the framebuffer, and it is more nasty as to start with a black screen.
I've backported console deferred takeover patch-series for fbcon [1], which permits the contents of the framebuffer (initialized before in U-Boot) to stay in place as is till error message is shown or boot is finished.
The initial splash is shown in U-Boot(mainline) (mxsfb driver is used for controller/fb initialization).
Nevertheless, MXSFB controller every time keeps resetting just after U-Boot->Linux takeover and fb is cleared (I see a black screen) till login request shows up.
Right.
Questions:
- Did anyone have a chance to work on such setups based on deferred
console "feature"? 2. Does it make sense at all to continue moving towards with this approach (we initialize graphics core and show boot splash by firmware/bootloader, then hand over it to Linux).
My personal point of view: it makes much more sense to invest the time to speed up the boot process, and let the kernel to boot in a shorten time. And if this time is short enough, kernel has initialized the framebuffer and can show something. This leads also to the main focus for U-Boot, that should be to start the kernel in the shortest time possible.
Taking into account on-going transition to DRM/KMS in the mainline kernel
Fully agree.
and that fact that there is no any mainline compatible way to take over an initialized graphics core, I assume the only generic solution could be avoiding showing boot logo
This is my position, too, and I do not show logo in U-Boot since some years (ok, since starting from DRM /KMS). And well, with i.MX6 / i.MX8, I do not see a chance without a very big effort, and IMHO it is not worth of it.
at all and do that only from the Linux ( Plymouth-based etc.)
Agree.
Any comments are welcome. Thanks!
Best regards, Stefano