Messages in this thread | | | Date | Sat, 14 Nov 2020 23:32:50 +0100 | From | Andrew Lunn <> | Subject | Re: [PATCH RFC v1 1/4] dt-bindings: net: dwmac-meson: use picoseconds for the RGMII RX delay |
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On Sat, Nov 14, 2020 at 09:01:01PM +0100, Martin Blumenstingl wrote: > Amlogic Meson G12A, G12B and SM1 SoCs have a more advanced RGMII RX > delay register which allows picoseconds precision. Deprecate the old > "amlogic,rx-delay-ns" in favour of a new "amlogic,rgmii-rx-delay-ps" > property. > > For older SoCs the only known supported values were 0ns and 2ns. The new > SoCs have 200ps precision and support RGMII RX delays between 0ps and > 3000ps. > > Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com> > --- > .../bindings/net/amlogic,meson-dwmac.yaml | 52 ++++++++++++++++++- > 1 file changed, 51 insertions(+), 1 deletion(-) > > diff --git a/Documentation/devicetree/bindings/net/amlogic,meson-dwmac.yaml b/Documentation/devicetree/bindings/net/amlogic,meson-dwmac.yaml > index 6b057b117aa0..bafde1194193 100644 > --- a/Documentation/devicetree/bindings/net/amlogic,meson-dwmac.yaml > +++ b/Documentation/devicetree/bindings/net/amlogic,meson-dwmac.yaml > @@ -74,18 +74,68 @@ allOf: > Any configuration is ignored when the phy-mode is set to "rmii". > > amlogic,rx-delay-ns: > + deprecated: true > enum: > - 0 > - 2 > default: 0 > + description: > + The internal RGMII RX clock delay in nanoseconds. Deprecated, use > + amlogic,rgmii-rx-delay-ps instead. > + > + amlogic,rgmii-rx-delay-ps: > + default: 0 > description: > The internal RGMII RX clock delay (provided by this IP block) in > - nanoseconds. When phy-mode is set to "rgmii" then the RX delay > + picoseconds. When phy-mode is set to "rgmii" then the RX delay > should be explicitly configured. When the phy-mode is set to > either "rgmii-id" or "rgmii-rxid" the RX clock delay is already > provided by the PHY. Any configuration is ignored when the > phy-mode is set to "rmii".
Hi Martin
I don't think the wording matches what the driver is actually doing:
if (dwmac->rx_delay_ns == 2) rx_dly_config = PRG_ETH0_ADJ_ENABLE | PRG_ETH0_ADJ_SETUP; else rx_dly_config = 0;
switch (dwmac->phy_mode) { case PHY_INTERFACE_MODE_RGMII: delay_config = tx_dly_config | rx_dly_config; break; case PHY_INTERFACE_MODE_RGMII_RXID: delay_config = tx_dly_config; break; case PHY_INTERFACE_MODE_RGMII_TXID: delay_config = rx_dly_config; break; case PHY_INTERFACE_MODE_RGMII_ID: case PHY_INTERFACE_MODE_RMII: delay_config = 0; break;
So rx_delay is used for both rgmii and rgmii-txid. The binding says nothing about rgmii-txid.
And while i'm looking at the code, i wonder about this:
if (rx_dly_config & PRG_ETH0_ADJ_ENABLE) { if (!dwmac->timing_adj_clk) { dev_err(dwmac->dev, "The timing-adjustment clock is mandatory for the RX delay re-timing\n"); return -EINVAL; }
/* The timing adjustment logic is driven by a separate clock */ ret = meson8b_devm_clk_prepare_enable(dwmac, dwmac->timing_adj_clk); if (ret) { dev_err(dwmac->dev, "Failed to enable the timing-adjustment clock\n"); return ret; } }
It looks like it can be that rx_dly_config & PRG_ETH0_ADJ_ENABLE is true, so the clock is enabled, but delay_config does not contain rx_delay_config, so it is pointless turning it on.
Andrew
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