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. But as far as I know it also needs proper (driver specific) Linux support, is that correct? So, I think its anyway worth having an option to properly disable the display and backlight for older kernels/non-Linux OS. -- 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