[U-Boot] [U-Boot, v5, 5/8] omap-common: SYS_BOOT-based fallback boot device selection for peripheral boot

From: Schmelzer Hannes <hannes@schmelzer.or.at>
To: u-boot@lists.denx.de
Subject: [U-Boot] [U-Boot, v5, 5/8] omap-common: SYS_BOOT-based fallback boot device selection for peripheral boot
Date: Tue, 25 Aug 2015 10:40:25 +0200	[thread overview]
Message-ID: <55DC29F9.8060701@schmelzer.or.at> (raw)
In-Reply-To: <20150728145914.GT25532@bill-the-cat>

Hi Paul, Tom,

i am failing bring up my AM335x boards (tseries, kwb) with bare UART 
connection since introducing this change.

--
U-Boot SPL 2015.10-rc2-00079-g35f2192-dirty (Aug 25 2015 - 07:34:24)
boot device - 0
SPL: Unsupported Boot Device (0)!
### ERROR ### Please RESET the board ###
---

The source of my problem is the __weak function in omap-common/boot-common.c

__weak u32 omap_sys_boot_device(void)
{
     return BOOT_DEVICE_NONE;
}

which one is called on line #82

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 ?

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 ?

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.

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.

How we want to deal with this facts ?

best regards,
Hannes

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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