RE: [PATCH v1 1/2] phy: keystone: serdes driver for gbe 10gbe and pcie

Kwok, WingMan
2015-10-15T23:54:36Z

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Hello,

> -----Original Message-----
> From: Rob Herring [mailto:robh+dt@kernel.org]
> Sent: Thursday, October 15, 2015 12:15 PM
> To: Kwok, WingMan
> Cc: Pawel Moll; Mark Rutland; Ian Campbell; Kumar Gala; KISHON VIJAY ABRAHAM;
> Quadros, Roger; Karicheri, Muralidharan; Bjorn Helgaas; Santosh Shilimkar;
> Russell King - ARM Linux; devicetree@vger.kernel.org; linux-
> kernel@vger.kernel.org; linux-pci@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org
> Subject: Re: [PATCH v1 1/2] phy: keystone: serdes driver for gbe 10gbe and
> pcie
>
> On Thu, Oct 15, 2015 at 9:25 AM, WingMan Kwok <w-kwok2@ti.com> wrote:
> > On TI's Keystone platforms, several peripherals such as the
> > gbe ethernet switch, 10gbe ethernet 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.
> >
> > This patch provides a SerDes phy driver implementation that can be
> > used by the above mentioned peripheral drivers to configure their
> > respective SerDeses.
> >
> > v1:
> > - see cover letter for review comments addressed.
> >
> > Signed-off-by: WingMan Kwok <w-kwok2@ti.com>
> > ---
> > Documentation/devicetree/bindings/phy/ti-phy.txt | 278 +++
> > drivers/phy/Kconfig | 8 +
> > drivers/phy/Makefile | 1 +
> > drivers/phy/phy-keystone-serdes.c | 2373
> ++++++++++++++++++++++
> > 4 files changed, 2660 insertions(+)
> > create mode 100644 drivers/phy/phy-keystone-serdes.c
> >
> > diff --git a/Documentation/devicetree/bindings/phy/ti-phy.txt
> b/Documentation/devicetree/bindings/phy/ti-phy.txt
> > index 9cf9446..4dca271 100644
> > --- a/Documentation/devicetree/bindings/phy/ti-phy.txt
> > +++ b/Documentation/devicetree/bindings/phy/ti-phy.txt
> > @@ -115,4 +115,282 @@ sata_phy: phy@4A096000 {
> > clock-names = "sysclk", "refclk";
> > syscon-pllreset = <&scm_conf 0x3fc>;
> > #phy-cells = <0>;
> > +
> > +TI Keystone SerDes PHY
> > +======================
> > +
> > +Required properties:
> > + - compatible: should be one of
> > + * "ti,keystone-serdes-gbe"
> > + * "ti,keystone-serdes-xgbe"
> > + * "ti,keystone-serdes-pcie"
>
> These are different blocks or different modes of the same block? It's
> fine if the former. If the latter, then you should have a single
> compatible and then have a mode property. Perhaps phy-connection-type
> from ePAPR ethernet binding can be extended.
>

these are different hw blocks configured specifically
for the corresponding peripheral.

>
> > + - reg:
> > + * base address and length of the SerDes register set
> > + - reg-names:
> > + * "serdes"
> > + - name of the reg SerDes register set
>
> reg-names is kind of pointless with only 1.
>

will remove.

> > + - #phy-cells:
> > + * From the generic phy bindings, must be 0;
> > + - num-lanes:
> > + * Number of lanes in SerDes.
> > +
> > +Optional properties:
> > + - syscon-peripheral:
> > + * Handle to the subsystem register region of the peripheral
> > + inside which the SerDes exists.
> > + - syscon-link:
> > + * Handle to the Link register region of the peripheral inside
> > + which the SerDes exists. Example: it is the PCSR register
> > + region in the case of 10gbe.
> > + - rx-force-enable:
> > + * Include this property if receiver attenuation and boost are
> > + to be configured with specific values defined in rx-force.
> > + - link-rate-kbps:
> > + * SerDes link rate to be configured, in kbps.
> > +
> > +
> > +For gbe and 10gbe SerDes, it is optional to represent each lane as
> > +a sub-node, which can be enabled or disabled individually using
> > +the "status" property.
> > +
> > +Required properties (lane sub-node):
> > + - reg:
> > + * lane number
> > +
> > +Optional properties (lane sub-node):
> > + - control-rate:
> > + * Lane control rate
> > + 0: full rate
> > + 1: half rate
> > + 2: quarter rate
> > + - rx-start:
> > + * Initial lane rx equalizer attenuation and boost configurations.
> > + * Must be array of 2 integers.
> > + - rx-force:
> > + * Forced lane rx equalizer attenuation and boost configurations.
> > + * Must be array of 2 integers.
> > + - tx-coeff:
> > + * Lane c1, c2, cm, attenuation and regulator output voltage
> > + configurations.
> > + * Must be array of 5 integers.
> > + - loopback:
> > + * Include this property to enable loopback at the SerDes
> > + lane level.
>
> This seems overly complicated. Do you really expect these to be
> different per lane?
>

It is an requirement that each lane can be enabled/disabled
and configured individually. Also it is potentially possible
that some of them are different due to calibration results.

> > +
> > +Example for Keystone K2E GBE:
> > +-----------------------------
> > +
> > +gbe_serdes0: gbe_serdes@232a000 {
> > + #phy-cells = <0>;
> > + compatible = "ti,keystone-serdes-gbe";
> > + reg = <0x0232a000 0x2000>;
> > + reg-names = "serdes";
> > + link-rate-kbps = <1250000>;
> > + num-lanes = <4>;
> > + lanes {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > + lane@0 {
> > + /*loopback;*/
> > + reg = <0>;
> > + control-rate = <2>; /* quart */
> > + rx-start = <7 5>;
> > + rx-force = <1 1>;
> > + tx-coeff = <0 0 0 12 4>;
> > + /* c1 c2 cm att vreg */
> > + };
> > + lane@1 {
> > + /*loopback;*/
> > + reg = <1>;
> > + control-rate = <2>; /* quart */
> > + rx-start = <7 5>;
> > + rx-force = <1 1>;
> > + tx-coeff = <0 0 0 12 4>;
> > + /* c1 c2 cm att vreg */
> > + };
> > + };
> > +};
> > +
> > +gbe_serdes1: gbe_serdes@2324000 {
> > + #phy-cells = <0>;
> > + compatible = "ti,keystone-serdes-gbe";
> > + reg = <0x02324000 0x2000>;
> > + reg-names = "serdes";
> > + link-rate-kbps = <1250000>;
> > + num-lanes = <4>;
>
> 4 lanes, but only 2 child nodes?
>

since each lane can be enabled/disabled individually, a disabled
lane can have a node defined but with a status = "disabled" or
does not have a lane node defined at all. this example shows the
latter.

> > + lanes {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > + lane@0 {
> > + /*loopback;*/
> > + reg = <0>;
> > + control-rate = <2>; /* quart */
> > + rx-start = <7 5>;
> > + rx-force = <1 1>;
> > + tx-coeff = <0 0 0 12 4>;
> > + /* c1 c2 cm att vreg */
> > + };
> > + lane@1 {
> > + /*loopback;*/
> > + reg = <1>;
> > + control-rate = <2>; /* quart */
> > + rx-start = <7 5>;
> > + rx-force = <1 1>;
> > + tx-coeff = <0 0 0 12 4>;
> > + /* c1 c2 cm att vreg */
> > + };
> > + };
> > +};
> > +
> > +netcp: netcp@24000000 {
> > + ...
> > +
> > + netcp-devices {
> > + ...
> > +
> > + gbe@200000 { /* ETHSS */
> > + ...
> > + serdeses {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > + serdes@0 {
> > + reg = <0>;
> > + phys = <&gbe_serdes0>;
> > + status = "ok";
> > + };
> > + serdes@1 {
> > + reg = <1>;
> > + phys = <&gbe_serdes1>;
> > + status = "ok";
>
> This is way too complex. Just do:
>
> phys = <&gbe_serdes0, &gbe_serdes1>;
>
> in the gbe node.
>

good point. will change to phys = <&gbe_serdes0>, <&gbe_serdes1>;

> Rob

Thanks,
WingMan
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