[U-Boot] [PATCH] imx_common: check for Serial Downloader in spl_boot_device

[Stefano Babic <sbabic@denx.de>]

Hi Eric,

On 05/12/2015 21:13, Eric Nelson wrote:
> Hi Stefano,
> 
> On 12/04/2015 02:02 AM, Stefano Babic wrote:
>> Check for bmode before reading the boot device
>> to check if a serial downloader is started,
>> and returns UART if the serial downloader is set,
>> letting SPL to wait for an image if
>> CONFIG_SPL_YMODEM_SUPPORT is set.
>>
>> This allows to load again a SPL based board
>> with imx_usb_loader together with a tool
>> such as kermit.
>>
>> Signed-off-by: Stefano Babic <sbabic@denx.de>
>> CC: Tim Harvey <tharvey@gateworks.com>
>> CC: Fabio Estevam <Fabio.Estevam@freescale.com>
>> CC: Eric Nelson <eric.nelson@boundarydevices.com>
>> ---
>>
>> Note: I know we have already discussed more complicated solution
>> 	for adding multilple files to imx_usb_loader.
>> 	However, fixing ymodem support for i.MX6
>> 	was trivial and imx_usb_loader is working
>> 	again.
>>
>>  arch/arm/imx-common/spl.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/arch/arm/imx-common/spl.c b/arch/arm/imx-common/spl.c
>> index ac6e40e..28217d2 100644
>> --- a/arch/arm/imx-common/spl.c
>> +++ b/arch/arm/imx-common/spl.c
>> @@ -20,7 +20,14 @@ u32 spl_boot_device(void)
>>  	struct src *psrc = (struct src *)SRC_BASE_ADDR;
>>  	unsigned int gpr10_boot = readl(&psrc->gpr10) & (1 << 28);
>>  	unsigned reg = gpr10_boot ? readl(&psrc->gpr9) : readl(&psrc->sbmr1);
>> +	unsigned int bmode = readl(&psrc->sbmr2);
>>  
>> +	/*
>> +	 * Check for BMODE if serial downloader is enabled
>> +	 * BOOT_MODE - see IMX6DQRM Table 8-1
>> +	 */
> 
> I think you may need to check only bits 24 and 25 here.
> 
>> +	if ((bmode >> 24) == 0x01) /* Serial Downloader */
>> +		return BOOT_DEVICE_UART;
> 
> Even though the data sheet says the high bits should be zero,
> I'm seeing some other bits set on an i.MX6SL:
> 
> 	=> mm 0x020d801c
> 	020d801c: 22000001 ? x
> 

Agree - I checked on Solo / DL, and bits were zero. I fix it in V2.

> Separately, what's your thought about enabling this when the
> system is reset through "bmode usb"?
> 
> http://git.denx.de/?p=u-boot.git;a=blob;f=arch/arm/cpu/armv7/mx6/soc.c;h=bf5ae8cdffd8b0887291249332b06f66dc644832;hb=HEAD#l389
> 
> Since the gpr9 value in this mode is 0x00000001, the switch
> statement currently falls into the NOR/OneNAND block, which
> is pretty useless.

I agree with you, in fact it does not work  - but I do not see a way to
inform the ROM that next time it should run with USB as boot device.
From the fusemap, I tried to set BOOT_CFG4 as 0x40 ("Reserved for serial
ROM"), and fixing BOOT_CFG1 to 0x30, but it was only a try. In fact, we
need to change BMODE from internal to serial, and I do not see a way in
the "official" documentation.

Regards,
Stefano


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