Re: [PATCH 1/5] usb: usb251xb: Add USB2517/i hub support

[Serge Semin]

On Thu, Sep 21, 2017 at 11:53:29AM -0500, Rob Herring <robh@xxxxxxxxxx> wrote:
> On Wed, Sep 20, 2017 at 4:15 PM, Serge Semin <fancer.lancer@xxxxxxxxx> wrote:
> > On Wed, Sep 20, 2017 at 03:52:35PM -0500, Rob Herring <robh@xxxxxxxxxx> wrote:
> >> On Sat, Sep 16, 2017 at 02:31:09AM +0300, Serge Semin wrote:
> >> > USB2517i hubs are very like USB251xb devices series. They have almost
> >> > the same configuration registers space except number of ports, led
> >> > configurations and lack of battery settings. All these peculiarities
> >> > are reflected in this patch.
> >> >
> >> > Signed-off-by: Serge Semin <fancer.lancer@xxxxxxxxx>
> >> > ---
> >> >  Documentation/devicetree/bindings/usb/usb251xb.txt |  4 +-
> >>
> >> Though Greg wants the code split, I want the binding as one change. H/w
> >> doesn't gain features one by one.
> >>
> >> It's preferred to split bindings to a separate patch.
> >>
> >
> > Folks, you are really driving people crazy. When I was reviewing a
> > kernel-patchset from a Logan-guy, I asked him to combine some of his patches,
> > since in fact their combination represented one solid driver. I was told to go
> > very far, and Greg supported him with it. I'm not going to be that rude and will
> > do as you asked me to. But really, isn't it possible to have some strict rule
> > created so a developer would always follow it thereby not being asked to
> > combine/split patches almost everytime?
> > The only way I see for now is to know each maintainer personal preferences.
> 
> That rule is in Documentation/devicetree/bindings/submitting-patches.txt.
> 
> I generally only ask to respin and split bindings if there's other changes.
> 

Great! I didn't know there is a document like that. Ok. From now I'll do as
it's prescribed there.

> >> >  drivers/usb/misc/usb251xb.c                        | 84 +++++++++++++++++++---
> >> >  2 files changed, 78 insertions(+), 10 deletions(-)
> >> >
> >> > diff --git a/Documentation/devicetree/bindings/usb/usb251xb.txt b/Documentation/devicetree/bindings/usb/usb251xb.txt
> >> > index 3957d4eda..3d84626d3 100644
> >> > --- a/Documentation/devicetree/bindings/usb/usb251xb.txt
> >> > +++ b/Documentation/devicetree/bindings/usb/usb251xb.txt
> >> > @@ -6,7 +6,8 @@ Hi-Speed Controller.
> >> >  Required properties :
> >> >   - compatible : Should be "microchip,usb251xb" or one of the specific types:
> >> >     "microchip,usb2512b", "microchip,usb2512bi", "microchip,usb2513b",
> >> > -   "microchip,usb2513bi", "microchip,usb2514b", "microchip,usb2514bi"
> >> > +   "microchip,usb2513bi", "microchip,usb2514b", "microchip,usb2514bi",
> >> > +   "microchip,usb2517", "microchip,usb2517i"
> >> >   - reset-gpios : Should specify the gpio for hub reset
> >> >   - reg : I2C address on the selected bus (default is <0x2C>)
> >> >
> >> > @@ -36,6 +37,7 @@ Optional properties :
> >> >     an invalid value is given, the default is used instead.
> >> >   - compound-device : indicate the hub is part of a compound device
> >> >   - port-mapping-mode : enable port mapping mode
> >> > + - speed-led-mode : led speed indiation mode selection (usb2517 only)
> >>
> >> This is a boolean or has values? What are valid values?
> >>
> >
> > It's boolean. Shall I rename it as:
> > "- speed-led-mode : enable led speed indication mode (usb2517 only)"?
> 
> Having the the word "boolean" in there would help.
> 
> >> This needs a vendor prefix. Somehow the other properties got in without.
> >>
> >
> > Hmm, it's not vendor specific, but device-specific. USB2517 is produced
> > by the same vendor - microchip. The new device got almost the same functionality as
> > the others, except number or ports, LED feature and battery enable feature.
> > The last one isn't configurable by dts. The rest of the properties are the same
> > for all the compatible devices. So what properties you are talking about then?
> 
> Well, we don't name things after devices. Properties are either common
> (either from DT Spec or a class of device (clocks, regulators, USB
> device, USB hubs, etc.)) or vendor specific. I haven't looked at which
> other ones specifically could be common for hubs or USB devices and
> which ones should be MicroChip specific.
> 

Alright. I found the recommended vendor-specific prefix, it's "microchip". What's 
next? The thing is, that this driver isn't usual USB root port controller driver.
It's the driver to perform the usb251x hubs configuration on boot time in accordance
with the hardware specifics. So to speak, this driver is something like EEPROM firmware
embedded in the kernel and configured by device tree node properties. I can't be sure,
whether all of these settings might be vendor specific, or some of them still can be
exposed by the hubs of other vendors. Most of the circuit designers just add real
EEPROMs to be connected to hubs, so their configurations would be loaded from them.
What shall we do with this bindings then? Shall we add the vendor-specific vendor to
the bindings file?

> Rob