On Sun, Oct 13, 2024 at 11:27:39PM +0200, Jan Petrous via B4 Relay wrote:

From: "Jan Petrous (OSS)" <jan.petrous@oss.nxp.com>

The helper rgmii_clock() implemented Russel's hint during stmmac
glue driver review:

  > We seem to have multiple cases of very similar logic in lots of stmmac
  > platform drivers, and I think it's about time we said no more to this.
  > So, what I think we should do is as follows:
  >
  > add the following helper - either in stmmac, or more generically
  > (phylib? - in which case its name will need changing.)
  >
  > static long stmmac_get_rgmii_clock(int speed)
  > {
  >        switch (speed) {
  >        case SPEED_10:
  >                return 2500000;
  >
  >        case SPEED_100:
  >                return 25000000;
  >
  >        case SPEED_1000:
  >                return 125000000;
  >
  >        default:
  >                return -ENVAL;
  >        }
  > }
  >
  > Then, this can become:
  >
  >        long tx_clk_rate;
  >
  >        ...
  >
  >        tx_clk_rate = stmmac_get_rgmii_clock(speed);
  >        if (tx_clk_rate < 0) {
  >                dev_err(gmac->dev, "Unsupported/Invalid speed: %d\n", speed);
  >                return;
  >        }
  >
  >        ret = clk_set_rate(gmac->tx_clk, tx_clk_rate);

Suggested-by: Russell King (Oracle) <redacted>
Signed-off-by: Jan Petrous (OSS) <jan.petrous@oss.nxp.com>

But of an unusual commit message, but it does explain the "Why?".

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

 
+/**
+ * rgmii_clock - map link speed to the clock rate
+ * @speed: link speed value
+ *
+ * Description: maps RGMII supported link speeds
+ * into the clock rates.
+ */

A Returns: line would be nice. 

	Andrew