Re: [PATCH v1 4/5] net: macb: Compatible as per device tree

[<Conor.Dooley@microchip.com>]

On 11/11/2021 12:54, Michael Walle wrote:
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> 
>>> If Linux driver does not need to be updated to support MPFS macb using
>>> existing compatible string but U-Boot driver has to, something is
>>> wrong on the U-Boot macb driver side.
>>>
>>> Would you please reconsider the whole changes?
>>>
>> We submitted patches(v1, v2) last year for the U-Boot MACB update for
>> 64-bit DMA access same like Linux MACB driver using "#ifdef
>> CONFIG_DMA_ADDR_T_64BIT" but one of the reviewer wanted to check 64-bit DMA
>> support at runtime instead of #ifdef and we updated the macb driver based
>> on the design config debug6 register of MACB hardware which supports 32-bit
>> or 64-bit DMA in patch(v3) but the SiFive FU540 MACB didn't work then the
>> reviewer suggested use compatible string instead of design config register
>> and updated same in patch(v4), these changes were tested and acknowledged
>> them at Patch v6.
> 
> I agree with Bin here. You shouldn't introduce a new compatible just for
> u-boot. If you need one, please to it first in linux and get an ACK there.
> Or at least there should be patches for it pending in linux and it should
> be likely, that they will be accepted.
> 
> Please work towards having one binding for u-boot and linux.
> 
> -michael
> 
I think the point that Padmarao is trying to make is that we don't need 
a new compatible for 64-bit DMA in the linux macb driver - we just use 
"cdns,macb" and enable CONFIG_ARCH_DMA_ADDR_T_64BIT. Padmarao previously 
submitted patches which would have introduced the same behaviour to 
u-boot, but after review was told to implement it using a compatible 
string specific to our board rather than copying the linux approach. 
Introducing that compatible string in linux would just be creating a 
superfluous binding, no?
Conor.