[U-Boot] [PATCH 12/14] ARM: AM43xx: EPOS_EVM: Add support for LPDDR2

[Vaibhav Bedia]

On Wed, Nov 6, 2013 at 8:45 AM, Lokesh Vutla <lokeshvutla at ti.com> wrote:
> On Wednesday 06 November 2013 06:27 PM, Vaibhav Bedia wrote:
>> On Mon, Nov 4, 2013 at 11:20 PM, Lokesh Vutla <lokeshvutla at ti.com> wrote:
>>> AM4372 EPOS EVM has 1GB LPDDR2(Part no: MT42L256M32D2LG-25 WT:A)
>>> Adding LPDDR2 init sequence and register details for the same.
>>> Below is the brief description of LPDDR2 init sequence:
>>> -> Configure VTP
>>> -> Configure DDR IO settings
>>> -> Disable initialization and refreshes until EMIF registers are programmed.
>>> -> Program Timing registers
>>> -> Program PHY control and Temp alert and ZQ config registers.
>>> -> Enable initialization and refreshes and configure SDRAM CONFIG register
>>> -> Wait till initialization is complete and the configure MR registers.
>>>
>>
>> Is there any public documentation to go with this?
>> I would suggest sprinkling the code with comments
>> to mention the different stages.
> Yep ll add the comments in the code..
>>
>> BTW, no IO powerdown setting for now?
> You mean DDR IO settings?

Yeah. I assume you have configured the dynamic power down bit properly.
Can't tell without looking at the TRM.

>>
>> [...]
>>>
>>> +ifeq ($(CONFIG_AM43XX),)
>>> +COBJS  += ddr.o
>>> +COBJS  += emif4.o
>>> +endif
>>> +COBJS-$(CONFIG_AM43XX) += emif4d5.o
>>> +
>>
>> Are the steps really different enough to warrant a new file? Can't the changes
>> be handled properly in the code? How has this been handled in OMAPx where
>> DDR3 and LPDDR both are supported?
> Initially Tom also suggested not to use a new file. I tried with not to add a new file,
> but I ended up with many #ifdefs. EMIF is new IP(reused from OMAP5) very different from AM33xx EMIF IP.
> So to make things more cleaner I had to use a new file..
>

It really looks a step backward. The new IP should be an update to the old
version and not just a complete overhaul of the programming model that folks
are familiar with.

Regards,
Vaibhav