Re: [PATCH v1 0/2] Common SerDes driver for TI's Keystone Platforms

[Murali Karicheri]

On 10/16/2015 04:02 AM, Russell King - ARM Linux wrote:
> On Thu, Oct 15, 2015 at 08:00:41PM -0500, Rob Herring wrote:
> > On Thu, Oct 15, 2015 at 11:51 AM, Russell King - ARM Linux
> > <linux@xxxxxxxxxxxxxxxx> wrote:
> > > On Thu, Oct 15, 2015 at 10:25:43AM -0400, WingMan Kwok wrote:
> > > > On TI's Keystone platforms, several peripherals such as the
> > > > gbe ethernet switch, 10gbe ethether switch and PCIe controller
> > > > require the use of a SerDes for converting SoC parallel data into
> > > > serialized data that can be output over a high-speed electrical
> > > > interface, and also converting high-speed serial input data
> > > > into parallel data that can be processed by the SoC.  The
> > > > SerDeses used by those peripherals, though they may be different,
> > > > are largely similar in functionality and setup.
> > >
> > > Given that serdes is not specific to TI, should this be specific to
> > > TI, or should there be an effort to come up with something which
> > > everyone who has serdes links can make use of?
Russell,

The serdes on K2 are re-used on multiple hardware blocks as already 
indicated in this thread. It has got multiple lanes, each lane can be 
enabled/disabled, shutdown etc. Isn't generic phy framework added to 
support this type of hardware block? I see some enhancements needed for 
K2 serdes to support monitoring the serdes link and providing a status 
to the higher layer device. So I am not clear what different way you 
would like to handle serdes drivers? Why do you need a new framework?

Murali
> > > Serdes comes in multiple different forms: PCIe, 1G SGMII ethernet,
> > > 1000base-X ethernet, 10g ethernet, SATA... I'd hate to see a
> > > plethora of SoC specific stuff for this.
> >
> > The licensed IP I've seen doesn't provide a standard register
> > interface, but just signals to the IP block. Same with PLL IP. So
> > we'll probably get to see vendors continue to differentiate on PHY
> > register design. :)
>
> So what?  Network drivers differ radically in register design, yet we
> still have a standardised interface to network drivers.


--
Murali Karicheri
Linux Kernel, Keystone
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