On 24.09.2018 16:56, Michael Nazzareno Trimarchi wrote: > Hi > > On Mon., 24 Sep. 2018, 4:51 pm Stefan Agner, <ste...@agner.ch> wrote: > >> On 24.09.2018 16:43, Michael Nazzareno Trimarchi wrote: >>> Hi >>> >>> On Thu., 16 Aug. 2018, 3:09 pm Stefan Agner, <ste...@agner.ch> >> wrote: >>> >>>> On 13.08.2018 09:30, Gerard Salvatella wrote: >>>>> Some boards require specific configuration prior to booting the >>>> kernel. >>>>> For instance, our boards require shutting down the display to >>>> avoid >>>>> fading transitions before the drivers are reloaded by the >> kernel. >>>> This >>>>> could be facilitated by adding an extra hook during the os >> booting >>>>> process. >>>> >>>> Maybe I can extend on what we are trying to achieve here: >>>> >>>> We enable display backlight using board code. >>> >>> You can make it works almost easily. >>> >>> I enable simple fb, inject allocated display parameters in dts to >>> reserve area, pass the area to the graphics controller and dismiss >> it >>> during probing >>> >>> This is mainline in linux support. >>> >>> I have couple of patches need to clean up for imx architecture >>> (imx6ull and imx25) >> >> Definitely interested in those patches! Of course using this >> approach >> leads to the most seamless booting experience. > > Yes but there are a lot of reason to have when you deal multi-image > update and so on. > >> But as far as I know it also needs proper (driver specific) Linux >> support, is that correct? > > No that is wrong. imx6ull need a small patches right now I have > applied in kernel in legacy driver and not in drm one. >
In what way is that different to what I wrote above? In the end, the OS needs support for this. > sunxi already implement everything in their side > >> So, I think its anyway worth having an option to properly disable >> the >> display and backlight for older kernels/non-Linux OS. > > gpio clear gpio-6 ; bootm ? That is very board specific scripting required. We enable the backlight in code, so we should disable it, especially if we disable the controller (which we do currently). -- Stefan > > Michael > >> -- >> Stefan >> >>> >>> You can still scripting it using cmd interface >>> >>> Michael >>> >>>> The architecture code then shuts down the display controller just >>>> before >>>> booting Linux (e.g. on i.MX, by calling >>>> ipuv3_fb_shutdown/lcdif_power_down in arch_preboot_os). >>>> >>>> This leads to a display which has backlight enabled, but no data >>>> driven... Depending on display this leads to noisy/fading >>>> transitions >>>> between U-Boot and Linux. >>>> >>>> So we would like to disable the backlight in board code. >>>> >>>> In a first version we used a weak display_shutdown() function, >> but >>>> with >>>> that we would have to add it to every architecture. >>>> >>>> This approach uses a generic board specific preeboot_os callback >>>> which >>>> can be used for different purpose too. >>>> >>>> Does this sound like an approach which is acceptable upstream? >>>> >>>> -- >>>> Stefan >>>> >>>>> >>>>> Signed-off-by: Gerard Salvatella <gerard.salvate...@toradex.com> >>>>> --- >>>>> common/bootm_os.c | 7 +++++++ >>>>> 1 file changed, 7 insertions(+) >>>>> >>>>> diff --git a/common/bootm_os.c b/common/bootm_os.c >>>>> index f4bd905909..1e7af56b64 100644 >>>>> --- a/common/bootm_os.c >>>>> +++ b/common/bootm_os.c >>>>> @@ -505,9 +505,16 @@ __weak void arch_preboot_os(void) >>>>> /* please define platform specific arch_preboot_os() */ >>>>> } >>>>> >>>>> +/* Allow for board specific config before we boot */ >>>>> +__weak void board_preboot_os(void) >>>>> +{ >>>>> + /* please define board specific board_preboot_os() */ >>>>> +} >>>>> + >>>>> int boot_selected_os(int argc, char * const argv[], int state, >>>>> bootm_headers_t *images, boot_os_fn *boot_fn) >>>>> { >>>>> + board_preboot_os(); >>>>> arch_preboot_os(); >>>>> boot_fn(state, argc, argv, images); >>>>> >>>>> -- >>>>> 2.18.0 >>>>> >>>>> >>>>> [Toradex Logo]<http://toradex.com> Global Leader in ArmĀ® >>>>> Embedded Computer Modules >>>>> >>>>> Choose >>>>> >>>> >>> >> > Us<https://www.toradex.com/how-to-choose-system-computer-on-module-partner> >>>>> | Products<https://www.toradex.com/products> | Developer >>>>> Center<http://developer.toradex.com/> | >>>>> Community<https://www.toradex.com/community> | >>>>> Careers<https://careers.toradex.com/> >>>>> Meet our engineers >>>>> >>>> >> at<https://www.toradex.com/events>:<https://www.toradex.com/events> >>>>> - Linux Developer Conference, Brazil, Aug 25-26, 2018 >>>>> - NXP Technology Days 2018, United States, Aug 28, 2018 >>>>> - IoT Latin America, Brazil, Aug 29-30, 2018 >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> U-Boot mailing list >>>>> U-Boot@lists.denx.de >>>>> https://lists.denx.de/listinfo/u-boot >>>> _______________________________________________ >>>> U-Boot mailing list >>>> U-Boot@lists.denx.de >>>> https://lists.denx.de/listinfo/u-boot _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot