Re: [PATCH v3 00/12] usb: dwc3: qcom: Flatten dwc3 structure

Konrad Dybcio
2025-01-28T10:42:07Z

On 27.01.2025 11:40 PM, Bjorn Andersson wrote:
> On Mon, Jan 27, 2025 at 06:57:41PM +0100, Stephan Gerhold wrote:
>> On Mon, Jan 13, 2025 at 09:11:33PM -0800, Bjorn Andersson wrote:
> [..]
>>> 118 files changed, 8389 insertions(+), 670 deletions(-)
>>> ---
>>
>> This is quite a lot of code and new files for a temporary migration.
>> It's also difficult to test these changes fully, since there are
>> separate overlays for each SoC and sometimes even each board.
>>
>> Would it be easier to just duplicate the dwc3-qcom driver for now?
>> Making a copy of the current dwc3-qcom.c would be just 1000 lines of
>> extra code, compared to more than 7000 for the overlay approach.
>>
>> The copy (e.g. dwc3-qcom-legacy.c) would keep handling the old bindings
>> with the existing code (that is known to work to some extent). We can
>> then improve upon the main version without risk of breaking any old
>> DTBs. If we decide to drop support for the old DTBs at some point, we
>> can just drop dwc3-qcom-legacy.
>>
>> This approach is also not pretty, but I think the risk and effort would
>> be lower than making sure the overlay approach works on all the affected
>> targets.
>>
>
> I like this suggestion.
>
> It's much more isolated and we know the current state of the driver
> works with the current dtbs out there - so backwards compatibility would
> be handled. I also did end up having to use separate compatibles for the
> old and new binding/driver, so this should be quite clean - i.e.
> nicer than the overlay-based path...
>
> The one drawback would be that devices that isn't updated to a new dtb
> would not gain the upcoming improved support for role switching, or any
> of the improvements in pm_runtime-support (as I assume we'd only care
> about the new driver). But I think that's worth the saving in
> complexity.

If a user explicitly decides not to update, there's only so much
we can do

Konrad