| Message ID | 20220119131117.30245-1-kabel@kernel.org |
|---|---|
| State | Accepted |
| Commit | 066c4b6ba06392e5929ea2ebd17622090b500b58 |
| Headers | show |
| Series | [devicetree,v3] dt-bindings: phy: Add `tx-p2p-microvolt` property binding | expand |
On 19.01.2022 14:11:17, Marek Behún wrote: > Common PHYs and network PCSes often have the possibility to specify > peak-to-peak voltage on the differential pair - the default voltage > sometimes needs to be changed for a particular board. > > Add properties `tx-p2p-microvolt` and `tx-p2p-microvolt-names` for this > purpose. The second property is needed to specify the mode for the > corresponding voltage in the `tx-p2p-microvolt` property, if the voltage > is to be used only for speficic mode. More voltage-mode pairs can be > specified. > > Example usage with only one voltage (it will be used for all supported > PHY modes, the `tx-p2p-microvolt-names` property is not needed in this > case): > > tx-p2p-microvolt = <915000>; > > Example usage with voltages for multiple modes: > > tx-p2p-microvolt = <915000>, <1100000>, <1200000>; > tx-p2p-microvolt-names = "2500base-x", "usb", "pcie"; > > Add these properties into a separate file phy/transmit-amplitude.yaml, > which should be referenced by any binding that uses it. If I understand your use-case correctly, you need different voltage p2p levels in the connection between the Ethernet MAC and the Ethernet switch or Ethernet-PHY? Some of the two wire Ethernet standards (10base-T1S, 10base-T1L, 100base-T1, 1000base-T1) defines several p2p voltage levels on the wire, i.e. between the PHYs. Alexandru has posed a series where you can specify the between-PHY voltage levels: | https://lore.kernel.org/all/20211210110509.20970-8-alexandru.tachici@analog.com/ Can we make clear that your binding specifies the voltage level on the MII interface, in contrast Alexandru's binding? regards, Marc
On 20.01.2022 19:01:55, Marek Behún wrote: > On Thu, 20 Jan 2022 09:49:14 +0100 > Marc Kleine-Budde <mkl@pengutronix.de> wrote: > > > On 19.01.2022 14:11:17, Marek Behún wrote: > > > Common PHYs and network PCSes often have the possibility to specify > > > peak-to-peak voltage on the differential pair - the default voltage > > > sometimes needs to be changed for a particular board. > > > > > > Add properties `tx-p2p-microvolt` and `tx-p2p-microvolt-names` for this > > > purpose. The second property is needed to specify the mode for the > > > corresponding voltage in the `tx-p2p-microvolt` property, if the voltage > > > is to be used only for speficic mode. More voltage-mode pairs can be > > > specified. > > > > > > Example usage with only one voltage (it will be used for all supported > > > PHY modes, the `tx-p2p-microvolt-names` property is not needed in this > > > case): > > > > > > tx-p2p-microvolt = <915000>; > > > > > > Example usage with voltages for multiple modes: > > > > > > tx-p2p-microvolt = <915000>, <1100000>, <1200000>; > > > tx-p2p-microvolt-names = "2500base-x", "usb", "pcie"; > > > > > > Add these properties into a separate file phy/transmit-amplitude.yaml, > > > which should be referenced by any binding that uses it. > > > > If I understand your use-case correctly, you need different voltage p2p > > levels in the connection between the Ethernet MAC and the Ethernet > > switch or Ethernet-PHY? > > This is a SerDes differential pair amplitude. So yes to your question, > if the MII interface uses differential pair, like sgmii, 10gbase-r, ... > > > Some of the two wire Ethernet standards (10base-T1S, 10base-T1L, > > 100base-T1, 1000base-T1) defines several p2p voltage levels on the wire, > > i.e. between the PHYs. Alexandru has posed a series where you can > > specify the between-PHY voltage levels: > > > > | https://lore.kernel.org/all/20211210110509.20970-8-alexandru.tachici@analog.com/ > > Copper ethernet is something different, so no conflict > > > Can we make clear that your binding specifies the voltage level on the > > MII interface, in contrast Alexandru's binding? > > The binding explicitly says "common PHY", not ethernet PHY. I don't > thing there will be any confusion. It can also be specified for USB3+ > differential pairs, or PCIe differential pairs, or DisplayPort > differential pairs... Thanks for the clarification. regards, Marc
On 1/19/22 5:11 AM, Marek Behún wrote: > Common PHYs and network PCSes often have the possibility to specify > peak-to-peak voltage on the differential pair - the default voltage > sometimes needs to be changed for a particular board. > > Add properties `tx-p2p-microvolt` and `tx-p2p-microvolt-names` for this > purpose. The second property is needed to specify the mode for the > corresponding voltage in the `tx-p2p-microvolt` property, if the voltage > is to be used only for speficic mode. More voltage-mode pairs can be > specified. > > Example usage with only one voltage (it will be used for all supported > PHY modes, the `tx-p2p-microvolt-names` property is not needed in this > case): > > tx-p2p-microvolt = <915000>; > > Example usage with voltages for multiple modes: > > tx-p2p-microvolt = <915000>, <1100000>, <1200000>; > tx-p2p-microvolt-names = "2500base-x", "usb", "pcie"; > > Add these properties into a separate file phy/transmit-amplitude.yaml, > which should be referenced by any binding that uses it. p2p commonly means peer to peer which incidentally could be confusing, can you spell out the property entire: tx-peaktopeak-microvolt or: tx-pk2pk-microvolt for a more compact name maybe?
diff --git a/Documentation/devicetree/bindings/phy/transmit-amplitude.yaml b/Documentation/devicetree/bindings/phy/transmit-amplitude.yaml new file mode 100644 index 000000000000..51492fe738ec --- /dev/null +++ b/Documentation/devicetree/bindings/phy/transmit-amplitude.yaml @@ -0,0 +1,103 @@ +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/phy/transmit-amplitude.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Common PHY and network PCS transmit amplitude property binding + +description: + Binding describing the peak-to-peak transmit amplitude for common PHYs + and network PCSes. + +maintainers: + - Marek Behún <kabel@kernel.org> + +properties: + tx-p2p-microvolt: + description: + Transmit amplitude voltages in microvolts, peak-to-peak. If this property + contains multiple values for various PHY modes, the + 'tx-p2p-microvolt-names' property must be provided and contain + corresponding mode names. + + tx-p2p-microvolt-names: + description: | + Names of the modes corresponding to voltages in the 'tx-p2p-microvolt' + property. Required only if multiple voltages are provided. + + If a value of 'default' is provided, the system should use it for any PHY + mode that is otherwise not defined here. If 'default' is not provided, the + system should use manufacturer default value. + minItems: 1 + maxItems: 16 + items: + enum: + - default + + # ethernet modes + - sgmii + - qsgmii + - xgmii + - 1000base-x + - 2500base-x + - 5gbase-r + - rxaui + - xaui + - 10gbase-kr + - usxgmii + - 10gbase-r + - 25gbase-r + + # PCIe modes + - pcie + - pcie1 + - pcie2 + - pcie3 + - pcie4 + - pcie5 + - pcie6 + + # USB modes + - usb + - usb-ls + - usb-fs + - usb-hs + - usb-ss + - usb-ss+ + - usb-4 + + # storage modes + - sata + - ufs-hs + - ufs-hs-a + - ufs-hs-b + + # display modes + - lvds + - dp + - dp-rbr + - dp-hbr + - dp-hbr2 + - dp-hbr3 + - dp-uhbr-10 + - dp-uhbr-13.5 + - dp-uhbr-20 + + # camera modes + - mipi-dphy + - mipi-dphy-univ + - mipi-dphy-v2.5-univ + +dependencies: + tx-p2p-microvolt-names: [ tx-p2p-microvolt ] + +additionalProperties: true + +examples: + - | + phy: phy { + #phy-cells = <1>; + tx-p2p-microvolt = <915000>, <1100000>, <1200000>; + tx-p2p-microvolt-names = "2500base-x", "usb-hs", "usb-ss"; + };
Common PHYs and network PCSes often have the possibility to specify peak-to-peak voltage on the differential pair - the default voltage sometimes needs to be changed for a particular board. Add properties `tx-p2p-microvolt` and `tx-p2p-microvolt-names` for this purpose. The second property is needed to specify the mode for the corresponding voltage in the `tx-p2p-microvolt` property, if the voltage is to be used only for speficic mode. More voltage-mode pairs can be specified. Example usage with only one voltage (it will be used for all supported PHY modes, the `tx-p2p-microvolt-names` property is not needed in this case): tx-p2p-microvolt = <915000>; Example usage with voltages for multiple modes: tx-p2p-microvolt = <915000>, <1100000>, <1200000>; tx-p2p-microvolt-names = "2500base-x", "usb", "pcie"; Add these properties into a separate file phy/transmit-amplitude.yaml, which should be referenced by any binding that uses it. Signed-off-by: Marek Behún <kabel@kernel.org> --- Change since v2: - removed 'select:' as requested by Rob. Instead the schema should be referenced by any binding that uses it. This also fixed indentation warnings from Rob's bot, since they warned about lines in the select statement --- .../bindings/phy/transmit-amplitude.yaml | 103 ++++++++++++++++++ 1 file changed, 103 insertions(+) create mode 100644 Documentation/devicetree/bindings/phy/transmit-amplitude.yaml