Re: [PATCH v2 2/2] net: phy: motorcomm: Add pad drive strength cfg support

Re: [PATCH v2 2/2] net: phy: motorcomm: Add pad drive strength cfg support
From: Guo Samin <redacted>
to: Andrew Lunn <andrew@lunn.ch>
data: 2023/5/6

Re: [PATCH v2 2/2] net: phy: motorcomm: Add pad drive strength cfg support
From: Andrew Lunn <andrew@lunn.ch>
to: Samin Guo <redacted>
data: 2023/5/5

quoted

quoted

 #define YTPHY_DTS_OUTPUT_CLK_DIS		0

@@ -1495,6 +1504,7 @@ static int yt8531_config_init(struct phy_device *phydev)
 {
 	struct device_node *node = phydev->mdio.dev.of_node;
 	int ret;
+	u32 ds, val;

Reverse Christmas tree.  Sort these longest first, shortest last.

Thanks, will fix.

quoted

Otherwise this looks O.K.

The only open question is if real unit should be used, uA, not some
magic numbers. Lets see what the DT Maintainers say.

      Andrew

Hi Andrew,

As I communicated with Frank, Motorcomm doesn't give specific units on their datasheet, except for magic numbers.
Tried to ask Motorcomm last week, but it seems that they themselves do not know what the unit is and have no response so far.


Below is all the relevant information I found：

Pad Drive Strength Cfg (EXT_0xA010)

Bit   |  Symbol           |  Access |  Default |  Description
15:13 |  Rgmii_sw_dr_rx   |  RW     |  0x3     |  Drive strenght of rx_clk pad.
                                               |  3'b111: strongest; 3'b000: weakest.

12    |  Rgmii_sw_dr[2]   |  RW     |  0x0     |  Bit 2 of Rgmii_sw_dr[2:0], refer to ext A010[5:4]

5:4   |  Rgmii_sw_dr[1:0] |  RW     |  0x3     |  Bit 1 and 0 of Rgmii_sw_dr, Drive strenght of rxd/rx_ctl rgmii pad.
                                               |  3'b111: strongest; 3'b000: weakest



Best regards,
Samin

Hi Andrew,

We tried contacting motorcomm again, but so far we haven't been able to get any more information about unit.
Also, I found a similar configuration in Documentation/devicetree/bindings/net/qca,ar803x.yaml, and they also
used the 'magic numbers':

  qca,clk-out-strength:
    description: Clock output driver strength.
    $ref: /schemas/types.yaml#/definitions/uint32
    enum: [0, 1, 2]


Best regards,
Samin