[PATCH 1/4] ARM: ep93xx: switch to SPARSEMEM

[Florian Fainelli]

On 05/26/2017 02:28 PM, Alexander Sverdlin wrote:
> Hello Florian,
> 
> On 26/05/17 18:13, Florian Fainelli wrote:
>>>> The EP93xx has four chip selects that can be used for the SDRAM memory.
>>>> These chip selects are decoded to specify an address domain:
>>>>
>>>>   SDCS3  0x00000000-0x0fffffff with Boot Option ASDO=1
>>>>   SDCS0  0xc0000000-0xcfffffff
>>>>   SDCS1  0xd0000000-0xdfffffff
>>>>   SDCS2  0xe0000000-x0efffffff
>>>>   SDCS3  0xf0000000-0xffffffff with Boot Option ASDO=0
>>>>
>>>> Because of the row/column/bank architecture of SDRAM, the mapping of
>>>> these memories into the processor's memory space is discontiguous.
>>>>
>>>> Most ep93xx systems only use one of the chip selects. For these systems,
>>>> ARCH_HAS_HOLES_MEMORYMODEL has worked fine to handle the discontiguous
>>>> memory.
>>>>
>>>> But, some of the TS-72xx boards use multiple chip selects. The TS-7300 in
>>>> particular uses SDCS3 (with ASDO=1) and SDCS2. On that system with
>>>> ARCH_HAS_HOLES_MEMORYMODEL the SDCS2 memory does not get handled correctly
>>>> and results in the system not booting.
>>>>
>>>> Change the EP93xx to ARCH_SPARSEMEM_ENABLE. This handles the discontiguous
>>>> memory for all configurations.
>>>>
>>>> This has been tested on the following ep93xx platforms:
>>>>
>>>> EDB9307A with 64 MiB on SDCS0
>>>> Vision EP9307 with 64 MiB on SDCS0
>>>> TS-7300 with 64 MiB on SDCS3 (with ASDO=1) and 64 MiB on SDCS2
>>>> sim.one with 64 MiB on SDCS0
>>>>
>>>> Signed-off-by: H Hartley Sweeten <hsweeten at visionengravers.com>
>>>> Tested-by: Linus Walleij <linus.walleij at linaro.org>
>>>> Cc: Russell King <linux at armlinux.org.uk>
>>> Tested-by: Florian Fainelli <f.fainelli at gmail.com>
>>>
>>> On a TS-3700 with 32MiB of SDRAM, thanks!
>>>
>> OK this is weird, this patch applied against v4.11 works fine on a 32MB
>> board configuration, but applied against v4.12-rc2 I now get the following:
>>
>> Uncompressing Linux... done, booting the kernel.
>> Warning: Neither atags nor dtb found
>>
>> as if r2 was lost somehow.
>>
>> I will start a bisection to figure out if/when it started to break.
>> Russell do you have an idea?
> 
> I've applied the patch to 4.12-rc2 as well (to be more precise, 1b8f2ffc of Linus's tree),
> and it boots fine on EDB9302 (32MiB one chip on SDCS3). I even ran "memtester" fine, one
> iteration.

I need to debug this further because it does not make sense to me why
this patch on 4.12-rc1 works but on on 4.1-2-rc2 other than just having
a bit more bloat one image vs. another.

Thanks!

> 
> So, from my PoV
> Tested-by: Alexander Sverdlin <alexander.sverdlin at gmail.com>
> 
> --
> Regards,
> Alexander.
> 


-- 
Florian