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

[Stefan Agner]

On 2016-11-15 10:04, Marek Vasut wrote:
> 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

Ok, I will send a v2 which moves it outside CONFIG_SPL_MMC_SUPPORT.

--
Stefan