stm32mp1 simple frame buffer

[Ara.1]

i have following yocto build configuration

Build Configuration:

BB_VERSION          = "1.42.0"

BUILD_SYS           = "x86_64-linux"

NATIVELSBSTRING     = "universal"

TARGET_SYS          = "arm-openstlinux_weston-linux-gnueabi"

DISTRO              = "openstlinux-weston"

DISTRO_VERSION      = "2.7-snapshot-20200721"

TUNE_FEATURES       = "arm vfp cortexa7 neon vfpv4 thumb callconvention-hard"

TARGET_FPU          = "hard"

DISTRO_CODENAME     = "warrior"

GCCVERSION          = "8.%"

need to what are the simple way to populate /dev/fb0, and draw a simple image RGB888 image , as i have parallel lcd RGB 24 bit display,

dont know what to add in kernel configuration, uboot level

any reference dtsi and more input

would be helpful

[Olivier GALLIEN]

Hi @Ara.1​ 

First I notice you are using DISTRO_CODENAME     = "warrior" which is not a supported distro by ST ( thud or dunfell)

For question about display did you already browse our wiki documentation ?

Guess some page may help you :

https://wiki.st.com/stm32mpu/wiki/DRM_KMS_overview

 LTDC device tree configuration and DSI device tree configuration

Hope it help

Olivier

[Ara.1]

Hi Oliver

attached is modtest and necessary log

following is the dts configuration

   panel-rgb@0 {

      compatible = "okaya,rs800480t-7x0gp", "simple-panel";

   pinctrl-names = "default", "sleep";

   pinctrl-0 = <&ltdc_mp1som_pins_a>;

   pinctrl-1 = <&ltdc_mp1som_sleep_pins_a>;

      status = "okay";

      port {

         panel_in_rgb: endpoint {

            remote-endpoint = <&ltdc_out_rgb>;

         };

      };

   };

/* disable DSI panel */

&dsi {

   status = "disabled";

};

&ltdc {

   status = "okay";

   port {

      ltdc_out_rgb: endpoint@0 {

      reg = <0>;

         remote-endpoint = <&panel_in_rgb>;

      };

   };

};

i can able to a white blank screen,

a. simple panel is getting probed successfully

anything else driver or configuration is missing , please let me know

[Ara.1]

attached is the drm log,

please let me know whats happening, still display is not up

[Qin.Bo]

hi, Olivier GALLIEN

I can display ok by drm with rgb888 lcd on stm32mp153, and "/dev/dri/card0" is ok.

but you know, stm32mp153 don't have gpu

I want running QT on stm32mp153 with "/dev/fb0"

so, how to create the "/dev/fb0"?

I try to modify de devicetree, but it still can't work well

Have you test "/dev/fb0" ok ,before? and how to modify?

thanks

[VRoma.2]

There is really no way to use simple framebuffer on mp151/153 devices?

DRM is the only ​method?

[AndreyK]

Look at CONFIG_DRM_FBDEV_EMULATION kernel build config param