diff mbox series

[RFC,v2,3/5] net: stmmac: dwmac-meson8b: use picoseconds for the RGMII RX delay

Message ID 20201115185210.573739-4-martin.blumenstingl@googlemail.com (mailing list archive)
State Superseded
Headers show
Series dwmac-meson8b: picosecond precision RX delay support | expand

Commit Message

Martin Blumenstingl Nov. 15, 2020, 6:52 p.m. UTC
Amlogic Meson G12A, G12B and SM1 SoCs have a more advanced RGMII RX
delay register which allows picoseconds precision. Parse the new
"amlogic,rgmii-rx-delay-ps" property or fall back to the old
"amlogic,rx-delay-ns".

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
 .../ethernet/stmicro/stmmac/dwmac-meson8b.c   | 22 ++++++++++++-------
 1 file changed, 14 insertions(+), 8 deletions(-)

Comments

Andrew Lunn Nov. 17, 2020, 2:04 a.m. UTC | #1
On Sun, Nov 15, 2020 at 07:52:08PM +0100, Martin Blumenstingl wrote:
> Amlogic Meson G12A, G12B and SM1 SoCs have a more advanced RGMII RX
> delay register which allows picoseconds precision. Parse the new
> "amlogic,rgmii-rx-delay-ps" property or fall back to the old
> "amlogic,rx-delay-ns".
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew
Florian Fainelli Nov. 17, 2020, 6:36 p.m. UTC | #2
On 11/15/20 10:52 AM, Martin Blumenstingl wrote:
> Amlogic Meson G12A, G12B and SM1 SoCs have a more advanced RGMII RX
> delay register which allows picoseconds precision. Parse the new
> "amlogic,rgmii-rx-delay-ps" property or fall back to the old
> "amlogic,rx-delay-ns".
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

Maybe also issue a warning when the 'amlogic,rx-delay-ns' property is
found in addition to the 'amlogic,rgmii-rx-delay-ps'? Up to you how to
manage existing DTBs being deployed.
Martin Blumenstingl Nov. 17, 2020, 10:50 p.m. UTC | #3
Hi Florian,

On Tue, Nov 17, 2020 at 7:36 PM Florian Fainelli <f.fainelli@gmail.com> wrote:
>
> On 11/15/20 10:52 AM, Martin Blumenstingl wrote:
> > Amlogic Meson G12A, G12B and SM1 SoCs have a more advanced RGMII RX
> > delay register which allows picoseconds precision. Parse the new
> > "amlogic,rgmii-rx-delay-ps" property or fall back to the old
> > "amlogic,rx-delay-ns".
> >
> > Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
>
> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
first of all: thanks for reviewing this (and the rest of the series)!

> Maybe also issue a warning when the 'amlogic,rx-delay-ns' property is
> found in addition to the 'amlogic,rgmii-rx-delay-ps'? Up to you how to
> manage existing DTBs being deployed.
none of the upstream DTBs uses amlogic,rx-delay-ns - and I am also not
aware of anything being in use "downstream".
I will add a sentence to the commit description when I re-send this
without RFC, something along those lines: "No upstream DTB uses the
old amlogic,rx-delay-ns (yet). Only include minimalistic logic to fall
back to the old property, without any special validation (for example:
old and new property are given at the same time)"

What do you think?


Best regards,
Martin
diff mbox series

Patch

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
index e27e2e7a53fd..03fce678b9f5 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
@@ -83,7 +83,7 @@  struct meson8b_dwmac {
 	phy_interface_t			phy_mode;
 	struct clk			*rgmii_tx_clk;
 	u32				tx_delay_ns;
-	u32				rx_delay_ns;
+	u32				rx_delay_ps;
 	struct clk			*timing_adj_clk;
 };
 
@@ -276,7 +276,7 @@  static int meson8b_init_prg_eth(struct meson8b_dwmac *dwmac)
 	tx_dly_config = FIELD_PREP(PRG_ETH0_TXDLY_MASK,
 				   dwmac->tx_delay_ns >> 1);
 
-	if (dwmac->rx_delay_ns == 2)
+	if (dwmac->rx_delay_ps == 2000)
 		rx_dly_config = PRG_ETH0_ADJ_ENABLE | PRG_ETH0_ADJ_SETUP;
 	else
 		rx_dly_config = 0;
@@ -406,14 +406,20 @@  static int meson8b_dwmac_probe(struct platform_device *pdev)
 				 &dwmac->tx_delay_ns))
 		dwmac->tx_delay_ns = 2;
 
-	/* use 0ns as fallback since this is what most boards actually use */
-	if (of_property_read_u32(pdev->dev.of_node, "amlogic,rx-delay-ns",
-				 &dwmac->rx_delay_ns))
-		dwmac->rx_delay_ns = 0;
+	/* RX delay defaults to 0ps since this is what many boards use */
+	if (of_property_read_u32(pdev->dev.of_node,
+				 "amlogic,rgmii-rx-delay-ps",
+				  &dwmac->rx_delay_ps)) {
+		if (!of_property_read_u32(pdev->dev.of_node,
+					  "amlogic,rx-delay-ns",
+					  &dwmac->rx_delay_ps))
+			/* convert ns to ps */
+			dwmac->rx_delay_ps *= 1000;
+	}
 
-	if (dwmac->rx_delay_ns != 0 && dwmac->rx_delay_ns != 2) {
+	if (dwmac->rx_delay_ps != 0 && dwmac->rx_delay_ps != 2000) {
 		dev_err(&pdev->dev,
-			"The only allowed RX delays values are: 0ns, 2ns");
+			"The only allowed RX delays values are: 0ps, 2000ps");
 		ret = -EINVAL;
 		goto err_remove_config_dt;
 	}