Creating boot.scr for u-boot
I generate image for a Freescale i.mx6 sabresd using Yocto. When booting, to activate the hdmi I have to modify u-boot by editing the bootargs. I use the following command :
setenv mmcargs 'setenv bootargs console=ttymxc0,115200 root=/dev/mmcblk2p2 rootwait rw video=mxcfb0:dev=hdmi, 1920x1080M@60, if=RGB24'
I can use saveenv to not enter it at every boot, but I'd like to automatize it to make the deployment easier. So I have made a boot.scr. Here is the boot.txt :
setenv mmcargs 'setenv bootargs console=ttymxc0,115200 root=/dev/mmcblk2p2 rootwait rw video=mxcfb0:dev=hdmi, 1920x1080M@60, if=RGB24'
boot
And I create the boot.scr using mkimage -A arm -T script -O linux -d boot.txt boot.scr. But, when booting, it makes a loop (boot make uboot reload the configuration, where it reads boot so it begin again). Without boot... no boot. I've tried a lot of possibilities : boot 0x120000000, bootm, bootz, with a lot of options, nothing works.
Answer
Most likely, your boot fails because you never load a kernel from which you could boot from.
In most cases, if bootcmd loads a boot.scr, then it is up to your boot.scr script to load the kernel (and also a device tree assuming you are using a recent iMX6 kernel). Then your script may boot with this kernel or allow bootcmd to carry on with its boot sequence using the loaded kernel. The load commands would look something like:
loadfdt=fatload mmc ${mmcdev}:${mmcpart} ${fdt_addr} ${fdt_file}
loaduimage=fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${uimage}
And the boot command should look something like:
run loaduimage; run loadfdt; bootm ${loadaddr} - ${fdt_addr}
You may already have an mmcboot command defined which already takes care of these.
I would remove the "boot" line from your script and instead load the kernel and device tree and then run bootm (or mmcboot) - basically try adding the above three lines to your script after setting mmcarg - you'll need to ensure all referenced variables are properly set (ie. mmcdev, mmpart, etc).