t1040 IFC flash driver Extended Chip Select

Scott Wood scott.wood at nxp.com
Tue Jul 12 02:55:42 AEST 2016

On 07/11/2016 11:36 AM, Daniel Walker wrote:
> On 07/08/2016 06:12 PM, Scott Wood wrote:
>> On 07/07/2016 06:48 PM, Daniel Walker wrote:
>>> On 07/07/2016 03:37 PM, Scott Wood wrote:
>>>> On 07/07/2016 05:01 PM, Daniel Walker wrote:
>>>>> On 07/07/2016 02:59 PM, Scott Wood wrote:
>>>>>> On 07/07/2016 04:49 PM, Daniel Walker wrote:
>>>>>>> On 07/07/2016 02:23 PM, Scott Wood wrote:
>>>>>>>> I suspect that add the usage of cspr_ext into the driver would fix the
>>>>>>>> issue we have. It reads like you would find that acceptable ?
>>>>>>>> What specifically is the problem you're having?  Is it that CSPR_EXT is
>>>>>>>> not getting written to, and thus the device does not appear at the
>>>>>>>> address that it should?
>>>>>>>> Or is the driver matching incorrectly?  The only way the driver's lack
>>>>>>>> of using CSPR_EXT to match would be a problem would be if you have
>>>>>>>> multiple chipselects with the same address in the lower 32 bits, and
>>>>>>>> only CSPR_EXT distinguishing them.  Since you proposed a device tree
>>>>>>>> binding that assumes all devices have the same CSPR_EXT, I doubt that's
>>>>>>>> the case, so I doubt adding CSPR_EXT matching to the driver will solve
>>>>>>>> your problem.
>>>>>>>> -Scott
>>>>>>> I didn't do the debug on this. From my perspective it's either flash
>>>>>>> works, or it doesn't work. We need the code below for it to work,
>>>>>> Adding CSPR_EXT matching to the driver will not accomplish the same
>>>>>> thing as that code.
>>>>> So from u-boot perspective, the values in the device tree under "ranges"
>>>>> or parts of it, are place into the cspr and cspr_ext ? Is that how it's
>>>>> suppose to work ?
>>>> U-Boot writes values that are hardcoded in the board config header.
>>>> These values (as well as the area covered by the IFC LAW) need to match
>>>> the address in the device tree, but U-Boot doesn't get them from the
>>>> device tree.
>>> I was suggesting the values it writes are the same as the ones inside
>>> the device tree. So we could have both csrp and csrp_ext written from
>>> the driver and the values would
>>> come from the ranges property.
>> There's more to CSPR than just the address.  The driver should either be
>> able to assume that all of CSPR/CSOR has been correctly initialized, or
>> it should assume none of that has been initialized -- which again,
>> requires the attribute information to be in the device tree.  If you're
>> doing something in between, then that's a board quirk rather than a
>> general solution.
>> -Scott
> It would seems like a good idea to add it then. I think it can be piece 
> mail, rather than all or nothing tho. How difficult is adding the other 
> part to the driver , v.s. just the cspr_ext ?

Writing only cspr_ext is a hack to work around a bug and should not be
disguised as a "piecemeal" implementation of something different.


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