[U-Boot] [PATCH v1 2/2] imx: use BOOT_DEVICE_BOARD instead of UART

[Stefan Agner]

On 2017-08-27 01:45, Sébastien Szymanski wrote:
> Hello,
> 
>> On 25 Aug 2017, at 13:33, Stefano Babic <sbabic at denx.de> wrote:
>>
>> On 16/08/2017 02:49, Stefan Agner wrote:
>>> From: Stefan Agner <stefan.agner at toradex.com>
>>>
>>> i.MX 6 serial downloader is not necessarily booting via UART but can
>>> also boot from USB. In fact only some i.MX chips have serial
>>> downloader support via UART (e.g. 6UL/ULL and Vybrid) but all of
>>> them have serial downloader support via USB. Use the more appropriate
>>> BOOT_DEVICE_BOARD define which is used for ROM provided recovery
>>> mechanisms in general.
>>>
>>> Signed-off-by: Stefan Agner <stefan.agner at toradex.com>
>>> ---
>>>
>>> arch/arm/mach-imx/spl.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-imx/spl.c b/arch/arm/mach-imx/spl.c
>>> index 836b334fa9..bcd1033fdb 100644
>>> --- a/arch/arm/mach-imx/spl.c
>>> +++ b/arch/arm/mach-imx/spl.c
>>> @@ -27,7 +27,7 @@ u32 spl_boot_device(void)
>>> 	 * BOOT_MODE - see IMX6DQRM Table 8-1
>>> 	 */
>>> 	if (((bmode >> 24) & 0x03) == 0x01) /* Serial Downloader */
>>> -		return BOOT_DEVICE_UART;
> 
> Returning BOOT_DEVICE_UART here makes the SPL to load U-Boot from the
> debug UART using a ymodem transfer when enabled with
> CONFIG_SPL_YMODEM_SUPPORT like it is on the OPOS6ULDev board. This is
> now broken.

For reference, the change has been discussed here:
https://www.mail-archive.com/u-boot@lists.denx.de/msg259729.html

Returning UART is definitely wrong, because the boot ROM can also boot
from USB... 

As I mentioned in the other thread, ideally we should be able to do a
runtime detection to discriminate between UART and USB loader. I think
Stefano did not like that since it relies on undocumented features.

So BOOT_DEVICE is really ambiguous. Maybe BOOT_DEVICE_* should be a
bitfield? Then we could return BOOT_DEVICE_UART and BOOT_DEVICE_USB, and
boards can just compile in the support they need.


Changing the Y-Modem support to boot device BOOT_DEVICE_BOARD is not
possible since other SoCs use BOOT_DEVICE_UART.

I guess we could just add a second SPL_LOAD_IMAGE_METHOD in
common/spl/spl_ymodem.c for BOOT_DEVICE_BOARD.

--
Stefan


> 
> Regards,
> 
>>> +		return BOOT_DEVICE_BOARD;
>>>
>>> 	/* BOOT_CFG1[7:4] - see IMX6DQRM Table 8-8 */
>>> 	switch ((reg & IMX6_BMODE_MASK) >> IMX6_BMODE_SHIFT) {
>>> @@ -43,7 +43,7 @@ u32 spl_boot_device(void)
>>> 		}
>>> 	/* Reserved: Used to force Serial Downloader */
>>> 	case IMX6_BMODE_RESERVED:
>>> -		return BOOT_DEVICE_UART;
>>> +		return BOOT_DEVICE_BOARD;
>>> 	/* SATA: See 8.5.4, Table 8-20 */
>>> 	case IMX6_BMODE_SATA:
>>> 		return BOOT_DEVICE_SATA;
>>>
>>
>> Applied to u-boot-imx, -master, thanks !
>>
>> Best regards,
>> Stefano Babic
>>
>>
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