[U-Boot] [PATCH 09/18] arm: mx6: ddr: do not write into reserved bit

Nikita Kiryanov
2014-08-04T12:49:29Z

Hi Tim,

On 04/08/14 08:43, Tim Harvey wrote:
> On Sun, Aug 3, 2014 at 12:34 AM, Nikita Kiryanov <nikita@compulab.co.il> wrote:
>> Bit 16 in mapsr register is in a reserved field. Don't write to it.
>>
>> Cc: Stefano Babic <sbabic@denx.de>
>> Cc: Tim Harvey <tharvey@gateworks.com>
>> Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
>> ---
>> arch/arm/cpu/armv7/mx6/ddr.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/cpu/armv7/mx6/ddr.c b/arch/arm/cpu/armv7/mx6/ddr.c
>> index af91314..70ce38f 100644
>> --- a/arch/arm/cpu/armv7/mx6/ddr.c
>> +++ b/arch/arm/cpu/armv7/mx6/ddr.c
>> @@ -466,7 +466,7 @@ void mx6_dram_cfg(const struct mx6_ddr_sysinfo *sysinfo,
>> 1 << 6 | /* BOTH_CS_PD */
>> (tcksrx & 0x7) << 3 |
>> (tcksre & 0x7);
>> - mmdc0->mapsr = 0x00011006; /* ADOPT power down enabled */
>> + mmdc0->mapsr = 0x00001006; /* ADOPT power down enabled */
>>
>> /* Step 11: Configure ZQ calibration: one-time and periodic 1ms */
>> val = 0xa1390003;
>> --
>> 1.9.1
>>
>
> Nikita,
>
> This makes sense per the reference manual, but does not agree with the
> i.Mx6DQSDL DDR3 Script Aid spreadsheet
> (https://community.freescale.com/docs/DOC-94917). I'm curious if you
> found any other explanation of this or anything else that makes you
> feel the spreadsheet is in error (vs the RM's).

Nothing specific, I just don't like to use undocumented features.
It's probably benign, but still...

> I've asked our Freescale FAE to clarify.

Looking forward to that...

Regards,
Nikita Kiryanov