[U-Boot] [linux-sunxi] [RFC 11/11] mtd/nand: Sunxi NAND boot partition definitions

[Yassin]

Hi Roy
Thank you for working on this, I would like to suggest if you could implement separate control commands to switch ECC and Randomisation modes per partitions. I know this is not the best approach but it will provide more controls.


> On 8 Jun 2015, at 7:11 pm, Roy Spliet <r.spliet at ultimaker.com> wrote:
> 
> Dear Michal,
> 
> Op 08-06-15 om 10:54 schreef Michal Suchanek:
>> On 8 June 2015 at 10:38, Roy Spliet <r.spliet at ultimaker.com> wrote:
>>> Hello Michal,
>>> 
>>> Op 07-06-15 om 18:48 schreef Michal Suchanek:
>>> 
>>> Hello,
>>> 
>>> On 5 June 2015 at 13:52, Roy Spliet <r.spliet at ultimaker.com> wrote:
>>> 
>>> Based on the default layout of the android image used at least on Olimex
>>> Lime
>>> 
>>> Signed-off-by: Roy Spliet <r.spliet at ultimaker.com>
>>> ---
>>>  include/configs/sunxi-common.h | 9 +++++++++
>>>  1 file changed, 9 insertions(+)
>>> 
>>> diff --git a/include/configs/sunxi-common.h b/include/configs/sunxi-common.h
>>> index ec28c40..b38f2f5 100644
>>> --- a/include/configs/sunxi-common.h
>>> +++ b/include/configs/sunxi-common.h
>>> @@ -404,8 +404,15 @@ extern int soft_i2c_gpio_scl;
>>>  #define BOOT_TARGET_DEVICES_USB(func)
>>>  #endif
>>> 
>>> +#ifdef CONFIG_NAND
>>> +#define BOOT_TARGET_DEVICES_NAND(func) func(NAND, nand , 0)
>>> +#else
>>> +#define BOOT_TARGET_DEVICES_NAND(func)
>>> +#endif
>>> +
>>>  #define BOOT_TARGET_DEVICES(func) \
>>>         BOOT_TARGET_DEVICES_MMC(func) \
>>> +       BOOT_TARGET_DEVICES_NAND(func) \
>>>         BOOT_TARGET_DEVICES_SCSI(func) \
>>>         BOOT_TARGET_DEVICES_USB(func) \
>>>         func(PXE, pxe, na) \
>>> @@ -441,6 +448,8 @@ extern int soft_i2c_gpio_scl;
>>>         MEM_LAYOUT_ENV_SETTINGS \
>>>         "fdtfile=" CONFIG_DEFAULT_DEVICE_TREE ".dtb\0" \
>>>         "console=ttyS0,115200\0" \
>>> +       "mtdids=nand0=mtd2\0" \
>>> +       "mtdparts=mtdparts=mtd2:0xffc00000 at 0x400000(nand0_main)\0" \
>>>         BOOTENV
>>> 
>>> From what I heard the nand boot partition size should be specified in
>>> nand pages rather than bytes because the boot rom loads a fixed number
>>> of pages and just uses the start of each page regardless of page size.
>>> 
>>> Although I believe you have the facts mostly right, they do not apply in
>>> this situation.
>>> What you are looking for is the partition definition for U-boot. At this
>>> point the boot
>>> rom (BROM) is no longer active and thus it's inner workings are mostly
>>> irrelevant.
>>> The NAND partition lay-out for the boards I have seen (various Olimex +
>>> Cubietruck..)
>>> are as follows:
>>> 0-2MB U-Boot-SPL + U-Boot
>> OK, so 0-2 MB has to be read (at least in part) by brom to load the
>> SPL so it must be in the format brom understands. The part containing
>> the SPL which is read by brom has certain number of pages. The u-boot
>> part can contain whatever we define.
>> 
>>> 2-4MB U-Boot SPL + U-Boot (for recovery)
>>> 4MB+ Main file system
>> The main filesystem has to be in format suitable for UBIFS. It has to
>> follow u-boot part possibly with some space in between.
>> 
>> If support for non-uniform flash format is not available then there
>> are basically two options:
>> 
>> 1) SPL supports brom format and u-boot binary is part of boot
>> partition. SPL can read/write itself and u-boot and u-boot can
>> read/write the main partition
>> 
>> 2) SPL and u-boot support the main partition format. While u-boot is
>> written to the boot partition its pages are written in the format
>> suitable for ubifs. This will get hairy when you want to actually
>> write u-boot and SPL.
>> 
>> The problem with counting the partition sizes in bytes is obvious -
>> whatever you do the brom reads predefined number of pages from the
>> start of the nand to load the SPL and unless you know maximum page
>> size of every nand ever made that is compatible with Allwinner brom
>> you cannot tell what is even the maximum size of this part in bytes.]
> The solution already implemented now and carried to Hans' tree is 1)
> with the size of SPL aligned to 8KB blocks (the largest of the page sizes
> attempted). The modes tried by BROM are listed in [1]. SPL currently
> tries only a single mode whose params are defined in sunxi-common.h,
> but this is likely to change to a "brute-force" approach to resemble
> BROM in the near future.
> Yours,
> 
> Roy
>> 
>> Thanks
>> 
>> Michal
> 
> [1] https://linux-sunxi.org/NAND
> 
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