arasan,sdhci.txt "compatibility" DT binding

[Sebastian Frias]

On 29/11/16 08:29, Rameshwar Sahu wrote:
> Hi Mason,
> 
> Nowhere in the documentation do they specify an "IP version".
> Some documents do provide a revision number, but that's just
> a *documentation* revision number, e.g.
> 
> changes in version 3.6 : fix typos
> changes in version 9.1a : update company logo
> 
> That's why Xilinx used "arasan,sdhci-8.9a" and APM used
> "arasan,sdhci-4.9a". These are documentation revisions.
> In my opinion, that information is mostly worthless.
> 

For the record, the important information conveyed by Rameshwar's
email is the following:

Arasan SD/SDIO/eMMC IP has a register which tells about the SD
specification version and  Vendor version number
Reg Name: Host controller version register (offset 0FEh)
bit [15:8] is for vendor version number,
But, I have seen that Arasaan vendor version number is same as
document revision number.

(At first I had ignored the email because it repeated Mason's email
without quoting, but then I realised it contained some information)



> 
> On Mon, Nov 28, 2016 at 10:22 PM, Mason <slash.tmp at free.fr> wrote:
>> On 28/11/2016 17:15, Arnd Bergmann wrote:
>>
>>> On Monday, November 28, 2016 4:44:39 PM CET Mason wrote:
>>>
>>>> Hello,
>>>>
>>>> @Shawn Lin, could you take a look below and tell me exactly
>>>> which IP core(s) Rockchip is using in its SoCs?
>>>>
>>>> Based on the feedback I received, here is an updated list of
>>>> compatible strings and controller versions dealt with by the
>>>> drivers/mmc/host/sdhci-of-arasan.c code.
>>>>
>>>>
>>>> Xilinx Zynq:
>>>> "SD2.0 / SDIO2.0 / MMC3.31 AHB Host Controller"
>>>> "arasan,sdhci-8.9a"
>>>> NB: 8.9a is the documentation revision (dated 2011-10-19)
>>>> subsequent tweaks labeled 9.0a, 9.1a, 9.2a
>>>>
>>>> Xilinx ZynqMP:
>>>> "SD3.0 / SDIO3.0 / eMMC4.51 AHB Host Controller"
>>>> "arasan,sdhci-8.9a"
>>>> NB: using the same compatible string as Zynq
>>>>
>>>> Sigma SMP87xx
>>>> "SD3.0 / SDIO3.0 / eMMC4.4 AHB Host Controller"
>>>> no compatible string yet, platform-specific init required
>>>>
>>>> APM:
>>>> "SD3.0 / SDIO3.0 / eMMC4.41 AHB Host Controller"
>>>> "arasan,sdhci-4.9a"
>>>> NB: 4.9a appears to be the documentation revision
>>>> no functional diff with "arasan,sdhci-8.9a"
>>>>
>>>> Rockchip
>>>> Exact IP unknown, waiting for Shawn's answer
>>>> "arasan,sdhci-5.1"
>>>> NB: 5.1 appears to refer to the eMMC standard supported
>>>>
>>>>
>>>> On a final note, there are many variations of the Arasan IP.
>>>> I've tracked down at least the following:
>>>>
>>>> SD_2.0_SDIO_2.0__MMC_3.31_AHB_Host_Controller.pdf
>>>> SD_3.0_SDIO_3.0_eMMC_4.41_OCP_Host_Controller.pdf
>>>> SD_3.0_SDIO_3.0_eMMC_4.4__AHB_Host_Controller.pdf
>>>> SD_3.0_SDIO_3.0_eMMC_4.51_Host_Controller.pdf
>>>> SD_3.0_SDIO_3.0_eMMC_4.5__Host_Controller.pdf
>>>> SD_4.1_SDIO_4.1_eMMC_4.51_Host_Controller.pdf
>>>> SD_4.1_SDIO_4.1_eMMC_5.1__Host_Controller.pdf
>>>>
>>>> It seems to me the compatible string should specify
>>>> the SD/SDIO version AND the eMMC version, since it
>>>> seems many combinations are allowed, e.g. eMMC 4.51
>>>> has two possible SD versions.
>>>>
>>>> What do you think?
>>>
>>> It seems wrong to have the eMMC or SD version in the compatible
>>> string.  Is that the only difference between the documents you
>>> found? Normally there should be a version of IP block itself,
>>> besides the supported protocol.
>>
>> But that is exactly the problem :-)
>>
>> Nowhere in the documentation do they specify an "IP version".
>> Some documents do provide a revision number, but that's just
>> a *documentation* revision number, e.g.
>>
>> changes in version 3.6 : fix typos
>> changes in version 9.1a : update company logo
>>
>> That's why Xilinx used "arasan,sdhci-8.9a" and APM used
>> "arasan,sdhci-4.9a". These are documentation revisions.
>> In my opinion, that information is mostly worthless.
>>
>>
>> Looking more closely at SD_3.0_SDIO_3.0_eMMC_4.4__AHB_Host_Controller.pdf
>> (User Guide, which has more info than Datasheet) I see this:
>>
>> Changed Host Controller Version Register value from 16'h0002 to 16'h7501
>> Changed Host Controller Version Register value from 16'h8301 to 16'h8401
>> Changed Host Controller Version Register value from 16'h8401 to 16'h8501
>> Changed Host Controller Version Register to 16'h9502
>> Changed Host Controller Version Register to 16'h9602
>> Changed Host Controller Version Register to 16'h9902
>>
>> Host controller version register (offset 0FEh)
>>
>> Vendor Version Number 15:8
>> HwInit=0x99
>> This status is reserved for the vendor version number.
>> The HD should not use this status.
>>
>> Specification Version Number 7:0
>> HwInit=0x02
>> This status indicates the Host Controller Spec. Version.
>> The upper and lower 4-bits indicate the version.
>> Description
>> 00 - SD Host Specification version 1.0
>> 01 - SD Host Specification version 2.00
>> including only the feature of the Test Register
>> 02 - SD Host Specification Version 3.00
>> others - Reserved
>>
>> I'm not sure what this "Vendor Version Number" specifies, nor if is
>> guaranteed to be unique across controllers.
>>
>> In SD_3.0_SDIO_3.0_eMMC_4.5__Host_Controller_UserGuide.pdf,
>> they write "The Vendor Version Number is set to 0x10 (1.0)"
>>
>> I don't have a UserGuide for "arasan,sdhci-5.1".
>>
>> Regards.
>>