Subject: Re: t1040 IFC flash driver Extended Chip Select

From: Daniel Walker <[email-masked]>
Date: Mon, 11 Jul 2016 09:36:19 -0700

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 ?

Daniel