[U-Boot] [PATCH] arm: mx6: specify SPL padding

[Marek Vasut]

On 11/15/2016 06:42 PM, Stefan Agner wrote:
> On 2016-11-15 08:12, Tom Rini wrote:
>> On Tue, Nov 15, 2016 at 09:59:22AM +0000, Max Krummenacher wrote:
>>> Hi Stefan
>>>
>>> On Mon, 2016-11-14 at 18:06 -0800, Stefan Agner wrote:
>>>> From: Stefan Agner <stefan.agner at toradex.com>
>>>>
>>>> When building SPL with eMMC boot support, specify standard padding
>>>> for payload to match the load sector during boot. This allows to
>>>> use the u-boot-with-spl.imx build target to generate a direcly
>>>> flashable image which can be flashed using:
>>>>
>>>>   dd if=u-boot-with-spl.imx of=/dev/mmcblk0 bs=512 skip=2
>>>>
>>>> Signed-off-by: Stefan Agner <stefan.agner at toradex.com>
>>>>
>>>> ---
>>>>
>>>>  include/configs/imx6_spl.h | 6 ++++++
>>>>  1 file changed, 6 insertions(+)
>>>>
>>>> diff --git a/include/configs/imx6_spl.h b/include/configs/imx6_spl.h
>>>> index 76d1ca0..ca3ed19 100644
>>>> --- a/include/configs/imx6_spl.h
>>>> +++ b/include/configs/imx6_spl.h
>>>> @@ -42,6 +42,12 @@
>>>>  #define CONFIG_SYS_MMCSD_FS_BOOT_PARTITION	1
>>>>  #define
>>>> CONFIG_SYS_MONITOR_LEN  (CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS/2*1024)
>>>>  #define CONFIG_SPL_ABORT_ON_RAW_IMAGE
>>>> +/*
>>>> + * SPL starts at 1KB (ROM offset), hence we need to pad SPL up to
>>>> 68KB so
>>>> + * that payload (U-Boot) will be at 69KB (sector 138) on the eMMC/SD
>>>> card.
>>>> + * Required for targets such as u-boot-with-spl.imx.
>>>> + */
>>>> +#define CONFIG_SPL_PAD_TO			0x11000
>>>>  #endif
>>>>  
>>>>  /* SATA support */
>>>
>>> This has been brought up already:
>>> https://www.mail-archive.com/u-boot@lists.denx.de/msg228246.html
>>> I agreed with Marek that this might disrupt other boot sources
>>> (NOR/SPI/ ...) which may or may not decide to use another offset
>>> between SPL and U-Boot.
>>> Thus it is advisable to move that define to the individual board
>>> configuration where one knows for what boot device one wants to
>>> use the combined u-boot-with-spl.imx binary.
>>
>> I'm going to have to disagree with Marek here then.  Looking over the
>> explanation in include/configs/imx6_spl.h we have:
>> 1KiB up front "wasted" for a partition table
>> 4KiB up next for the ROM-mandated header
>> 64KiB for SPL itself, which is our max size, unconditionally set above
>> this bit of context.  But it is the lowest common denominator in terms
>> of IRAM size in the families.
>>
>> Which brings us to the SPL_PAD_TO above, 68KiB.  We cannot go lower than
>> this.  No one is changing any of this either today nor setting
>> SPL_PAD_TO so
>> u-boot-with-spl.imx isn't usable today.  None of this breaks using
>> separate files.
> 
> I agree here, the pad seems pretty natural and should be usable across
> boot devices. In fact, it probably should not be inside
> CONFIG_SPL_MMC_SUPPORT, but at the top along with CONFIG_SPL_MAX_SIZE.
> 
> So far, include/config_fallbacks.h defined SPL_PAD_TO to 64KiB, which
> renders u-boot-with-spl.imx unusable for SD/eMMC boot. Other boot
> devices probably know a similar define (CONFIG_SYS_NAND_U_BOOT_OFFS).
> Judging from existing board files it does not seem that anybody relied
> on that 64kB padding so far... I guess if a board with a different boot
> device wants to make use of u-boot-with-spl.imx, then it should make
> sure that the offset is set correctly in its board file (e.g. using
> #define CONFIG_SYS_NAND_U_BOOT_OFFS SPL_PAD_TO).
> 
> Marek?

I'm fine with it, esp. now that the other boot media are checked. Thanks

-- 
Best regards,
Marek Vasut