Le mardi 25 août 2015 à 10:40 +0200, Schmelzer Hannes a écrit :
Hi Paul, Tom,
i am failing bring up my AM335x boards (tseries, kwb) with bare UART connection since introducing this change.
Does this mean that you're trying to get the device to load the full U-Boot binary over UART?
For my understanding this function should be called allways if chip has basically support for some BOOT_DEVICE_x __AND__ there is no implementation for it - the function should prevent target from stalling with selecting another (hopefully working) boot-device. Right ?
This is a fallback mechanism that allows selecting the boot device from the SYS_BOOT pins when the U-Boot SPL was loaded from peripheral booting (USB or UART) by the bootrom and that the U-Boot SPL has no support for continuing boot through that same peripheral (USB or UART).
It does require omap_sys_boot_device to be implemented for each platform (currently, only am33xx doesn't have a proper one). The point is that it selects another *memory* (read, not peripheral) boot device that the U-Boot SPL may be able to handle.
In any case, it offers a way to *maybe* put the U-Boot SPL on the right track instead of being unable to boot at all.
I am not sure at this time how to deal with the facts ... i see several possibilities:
a) i have to implement some "omap_sys_boot_device" function in my boards
- this would maybe sometimes comfortable but i think this is not
inventors mind. It would be more convenient to implement it in some common place for AM335x or OMAP. But what do with the information about SYS_BOOT pins ? they always represent a boot-order ... which boot-device should it take ?
That function is not supposed to be board-specific at all, but to be platform-specific. This is not the way to select the proper boot device, which is done by reading the boot info structure passed by the bootrom (first thing in omap-common/lowlevel_init.S).
b) and/or something is wrong with the #ifdef ... construct at line #67
In fact there is a problem with defined(BOOT_DEVICE_USBETH) && !defined(CONFIG_SPL_USBETH_SUPPORT)
basicaly BOOT_DEVICE_USBETH is defined in spl.h but in my configuration there is no #define for CONFIG_SPL_USBETH_SUPPORT and so the following switch/case calls in case of BOOT_DEVICE_UART this weak function.
If I got everything right, the bootrom is passing BOOT_DEVICE_UART as boot device, but you haven't selected CONFIG_SPL_YMODEM_SUPPORT. Thus, it falls back to asking omap_sys_boot_device, which is not implemented.
The real problem here is that you have not enabled support for loading the main U-Boot binary via UART, with CONFIG_SPL_YMODEM_SUPPORT.
UART booting is unrelated to CONFIG_SPL_USBETH_SUPPORT.
further i think that this construct isn't complete yet, because it wants to handle all peripheral booting on AM335x or OMAP in general.
following peripherals are currently handled:
BOOT_DEVICE_UART BOOT_DEVICE_USB BOOT_DEVICE_USBETH
but there is also BOOT_DEVICE_CPGMAC
Summary i think this changeset isn't complete.
Can the bootrom indicate that it booted from BOOT_DEVICE_CPGMAC? I haven't seen that and don't really know what it corresponds to. But if you think it is concerned by this fallback mechanism, you could add support for it. I only made this for the omap devices I have (and I don't have any am33xx board) and I didn't want to blindly implement too much for am33xx.
On 28.07.2015 16:59, Tom Rini wrote:
On Wed, Jul 15, 2015 at 04:02:23PM +0200, Paul Kocialkowski wrote:
OMAP devices might boot from peripheral devices, such as UART or USB. When that happens, the U-Boot SPL tries to boot the next stage (complete U-Boot) from that peripheral device, but in most cases, this is not a valid boot device.
This introduces a fallback option that reads the SYS_BOOT pins, that are used by the bootrom to determine which device to boot from. It is intended for the SYS_BOOT value to be interpreted in the memory-preferred scheme, so that the U-Boot SPL can load the next stage from a valid location.
Practically, this options allows loading the U-Boot SPL through USB and have it load the next stage according to the memory device selected by SYS_BOOT instead of stalling.
Signed-off-by: Paul Kocialkowski contact@paulk.fr
Applied to u-boot/master, thanks!
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