Re: [PATCH] phy: nop: Add a new phy driver for No-Op transceiver

[Vivek Gautam]

Hi Kishon,


On 10/05/2016 05:41 PM, Kishon Vijay Abraham I wrote:
> Hi,
>
> On Tuesday 04 October 2016 04:13 PM, Vivek Gautam wrote:
> > No-Op phy transceiver can be used on platforms that have
> > controllers which themselves provide PHY functionality and
> > there's no separate PHY controller available.
> >
> > This driver provides a basic skeleton for a nop-phy driver.
> > This can be further extended to add required features.
> >
> > Inspired by phy-generic driver in drivers/usb/phy.
> >
> > Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
> > Cc: Kishon Vijay Abraham I <kishon@xxxxxx>
> > Cc: Felipe Balbi <balbi@xxxxxxxxxx>
> > ---
> >
> > Hi Kishon, Felipe,
> >
> > This patch has been lying in my tree for sometime.
> > This introduces a skeletal nop-phy driver based on generic
> > phy framework.
> > I mainly use this driver when I have only one phy driver available
> > for testing for a controller that uses more than one phy.
> >
> > But this can be further extended to add any feature support for
> > controllers that don't have a separate PHY controller and that
> > themselves provide the PHY functionality, a purpose similar
> > to what drivers/usb/phy/phy-generic.c driver serves.
> >
> > Do you think we have a requirement for such a driver in the generic
> > phy layer? I hope this driver can do some good.
> > Let me know your comments on this.
> >
> > Thanks
> > Vivek
> >
> >   Documentation/devicetree/bindings/phy/phy-nop.txt |  22 +++
> >   drivers/phy/Kconfig                               |  10 ++
> >   drivers/phy/Makefile                              |   1 +
> >   drivers/phy/phy-nop.c                             | 193 ++++++++++++++++++++++
> >   4 files changed, 226 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/phy/phy-nop.txt
> >   create mode 100644 drivers/phy/phy-nop.c
> >
> > diff --git a/Documentation/devicetree/bindings/phy/phy-nop.txt b/Documentation/devicetree/bindings/phy/phy-nop.txt
> > new file mode 100644
> > index 0000000..6cb6779
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/phy/phy-nop.txt
[snip]

> > +
> > +Example:
> > +	phy_nop: phy_nop {
> > +		compatible = "phy-nop";
> > +		#phy-cells = <0>;
> > +	};
> I don't think this qualifies to be modeled as dt. device tree should try to
> represent HW and not workaround SW issues by creating dummy nodes. For such
> cases phy_optional_get should suffice?

You are right. The device tree should model the hardware on the platform.
But what i am trying to model here is a simple phy binding that the 
users can
use taking a phandle for this PHY in their device nodes.

> I'm more towards having a simple-phy, along the lines of [1]
>
> [1] -> https://patchwork.kernel.org/patch/8153691/

Cool, the above patch looks good, and is quite similar to what i meant 
to do.
I will drop this one.

But that patch hasn't move forward. I will ping in that thread, so that we
can have a re-spin of that patch that can be reviewed further and merged.

> Thanks
> Kishon
[snip]


Thanks
Vivek