[U-Boot] [PATCH 2/2] arm: imx6: Enable DDR calibration on Novena

[Nikolay Dimitrov]

Hi Marek,

On 12/22/2015 03:26 AM, Marek Vasut wrote:
> On Sunday, December 20, 2015 at 08:33:58 PM, Eric Nelson wrote:
>> Hi Marek,
>>
>> On 12/16/2015 07:40 AM, Marek Vasut wrote:
>>> Enable the DDR calibration functionality on Novena to deal with the
>>> memory SoDIMM on this board.
>>
>> Shouldn't this be in two patches?
>
> Not really, the old values work without the enabled calibration. This
> change needs to be done atomically.
>
> [...]
>
>>>   static void ccgr_init(void)
>>>
>>> @@ -601,6 +601,11 @@ void board_init_f(ulong dummy)
>>>
>>>   	mx6dq_dram_iocfg(64, &novena_ddr_ioregs, &novena_grp_ioregs);
>>>   	mx6_dram_cfg(&novena_ddr_info, &novena_mmdc_calib, &elpida_4gib_1600);
>>>
>>> +	/* Perform DDR DRAM calibration */
>>> +	udelay(100);
>>
>> Shouldn't the return values be tested?
>
> I guess yes, but if the calibration fails, that what ? It's game over ;-)

Do you think it's possible/practical to reboot the system in this case?

>
> I will just change those functions to void type and do hang() if we get errors.
> I believe that's the most sane way to handle it and it prevents development of
> boilerplate code.
>
>>> +	mmdc_do_write_level_calibration();
>>> +	mmdc_do_dqs_calibration();
>>> +
>>>
>>>   	/* Clear the BSS. */
>>>   	memset(__bss_start, 0, __bss_end - __bss_start);
>
> Best regards,
> Marek Vasut
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>

Regards,
Nikolay