[U-Boot] [PATCH v2] rockchip: rk3288-evb: dts: remove 'vmmc' from emmc node

[Kever Yang]

Hi Tom,


On 12/07/2018 10:13 PM, Tom Rini wrote:
> On Fri, Dec 07, 2018 at 02:24:22PM +0100, Philipp Tomsich wrote:
>> Kever,
>>
>>> On 07.12.2018, at 02:39, Kever Yang <kever.yang at rock-chips.com> wrote:
>>>
>>> Hi Philipp,
>>>
>>> On 12/06/2018 09:50 PM, Philipp Tomsich wrote:
>>>> +Tom
>>>>
>>>>> On 05.12.2018, at 03:25, Kever Yang <kever.yang at rock-chips.com> wrote:
>>>>>
>>>>> The U-Boot eMMC does not need to care about the power for Rockchip
>>>>> SoC, because if the board is using eMMC, the power will default on
>>>>> (for bootrom), and we do not do power management for it like kernel,
>>>>> so the 'vmmc', 'vqmmc' is only useful for SD in U-Boot.
>>>>>
>>>>> This make U-Boot can boot into kernel even if the pmic driver is
>>>>> broken.
>>>> If the PMIC driver is broken, we should fix the PMIC driver.
>>>> I would feel more comfortable w/o this statement.
>>>>
>>>>> The rk3288-evb dts may be used in many boards using rockchip reference
>>>>> schematic but with little change, so we hope it can be more robust to
>>>>> boot into next stage.
>>>> Again, this is not how the DTS should be used.  I believe that Heiko, Fabio and
>>>> I had already highlighted this in comments to the earlier thread.
>>>     Not sure if you have read my previous mail for answer all your comments,
>>>
>>> I do agree DTS should represent the hardware, but please note that the DTS
>>> is no kind of standard, and people always choose what they need and add
>>> those part in there dts, but not always add all the property and
>>> everyone use the same model. I would say there are many boards does not have this
>>> 'vmmc-supply’ in there emmc node.
>> That is exactly the reason why I bumped the decision up the stairs (to Tom and/or
>> Simon): what you are saying makes sense to me (viewed through your eyes and 
>> from your specific usecase), but it directly contradicts how the DTS usage is intended.
>>
>> In other words: Tom (as the top-level decision maker) or Simon (who owns the 
>> device-model and therefore will also have an opinion on DTS usage) should make
>> the final call.
> My answer is that I would strongly suspect that over in linux "we have N
> different close-enough boards using this one DTS" isn't acceptable.  You
> make a dtsi and include it from the board and things that aren't common
> don't go into the dtsi.  And yes, when starting off everyone (myself
> included) copies the reference platform dts and then changes it as
> needed, and sometimes misses a thing or two.  But no, I don't think we
> want a wrong dts and I'm pretty sure the kernel really wouldn't want
> wrong dts files and the general goal is that excluding the -u-boot.dtsi
> files, ours are copies of the kernel.
I don't think this is a "wrong dts" after my patch, these two nodes are
not mark
as required property in kernel, so many dts emmc node does not have it.
I check the latest kernel dtsi in arch/arm/boot/dts/rk3288-evb.dtsi [1],
the emmc node do not have 'vmmc' and 'vqmmc' while the SD node have, which
just like description in my commit message.

Well, I don't know why U-Boot project is so difficult to accept a
reasonable patch now, I don't
want to make you unhappy, but make 'every board must have its own dts'
in U-Boot to make
every developer to join U-Boot does not make sense to me. The kernel
need different
dts for different board because they need to use/control those different
feature, but U-Boot
is not the case, U-Boot should work if the storage driver works.

Thanks,
- Kever

[1]
https://github.com/torvalds/linux/blob/master/arch/arm/boot/dts/rk3288-evb.dtsi#L208
>