Re: [PATCH for-4.11 1/2] Revert "phy: Add USB3 PHY support for Broadcom NSP SoC"

[Florian Fainelli <f.fainelli@gmail.com>]

On 02/08/2017 11:21 PM, Rafał Miłecki wrote:
> On 2017-02-09 00:44, Florian Fainelli wrote:
>> On 02/08/2017 03:39 PM, Rafał Miłecki wrote:
>>> On 2017-02-09 00:32, Florian Fainelli wrote:
>>>> On 02/08/2017 03:30 PM, Rafał Miłecki wrote:
>>>>> From: Rafał Miłecki <rafal@milecki.pl>
>>>>>
>>>>> This reverts commit d7bc1a7d41bf ("phy: Add USB3 PHY support for
>>>>> Broadcom NSP SoC") as we already have driver for this PHY (shared
>>>>> by NS
>>>>> and NSP). It was added in commit e5666281d9ea ("phy: bcm-ns-usb3: new
>>>>> driver for USB 3.0 PHY on Northstar").
>>>>>
>>>>> Instead of adding separated driver & duplicating code we should
>>>>> work on
>>>>> improving existing (old) one. Thanks to work done by Broadcom we know
>>>>> there is MDIO bus we weren't aware of & we know register names which
>>>>> makes initialization more clear. This is very valuable info and we
>>>>> should work on using it in existing driver afterwards.
>>>>
>>>> Should not we first extend the old driver to support NSP and then
>>>> revert
>>>> d7bc1a7d41bf ("phy: Add USB3 PHY support for Broadcom NSP SoC")?
>>>
>>> Sounds like a weird / dirty development method to me: adding duplicated
>>> code
>>> first then working on cleaning it. Unless you mean drivers/staging/.
>>
>> There was clearly a mistake in submitting this NSP USB PHY driver, and
>> it should have been a patch against the existing NS USB PHY driver, but
>> it was not, okay fair enough.
>>
>> It's one thing to address that in the future, and it's another thing to
>> flat out revert the driver just because you don't like the duplication.
>>
>> I don't like that either, and we can discuss on how to improve things
>> (like have the maintainer review that too), but duplication is a lesser
>> evil than not having the hardware supported at all, and even more so,
>> purposely reverting in the name of removing that duplication, that's
>> intentionally breaking working hardware!
> 
> Hardware support is not excuse and I don't think it ever was in the Linux.
> 
> We don't accept badly designed drivers just because they provide new hw
> support.
> We have various standards (for quality, style, design, code) at kernel
> and we
> stick to them unless it's drivers/staging/. As you said this driver
> shouldn't be
> pushed in the first place.
> 
> Dropping hardware support in kernel happens. Sometimes it's about ancient
> devices, sometimes about code quality (some forgotten staging drivers
> used to be
> dropped AFAIK).
> 
> Additionally you're talking about support that was *just* added and
> isn't used
> by anyone in the wild world yet.

Except people working on it at Broadcom, but fair enough.

> 
> This hardware was missing upstream support for 4 years so 2 extra months
> won't
> really hurt anyone.
> 
> I really don't see excusee or need for keeping this driver.
> 
> If you want to (and you feel it's well designed), we can keep
> brcm,nsp-usb3-phy.txt

No it's fine, let's drop it all and replace it with whatever you and Jon
come up with next.

> 
> I vote for focusing on existing driver improvements instead of looking for
> excuses for keeping driver that shouldn't be added in the first place.
> Jon seems to be already working on this, I'm willing to help him, I'm
> sure we
> can get you a proper support for the next merge window.

Fair enough, I dropped Dhanajay's changes ("ARM: dts: NSP: Add USB nodes
for Northstar Plus") from devicetree/next so you and Jon can figure out
what is the best thing to move forward and we minimize the amount of
incompatible DT stuff to be sorted out later on. So as far as I am
concerned, there are no board/SoC DTS changes to be patched later on, we
could re-apply this patch as-is, or we could have to define a new binding.
-- 
Florian

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