Messages in this thread | | | From | Peter Geis <> | Date | Fri, 14 May 2021 10:09:18 -0400 | Subject | Re: [PATCH v3] net: phy: add driver for Motorcomm yt8511 phy |
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On Fri, May 14, 2021 at 9:09 AM Russell King (Oracle) <linux@armlinux.org.uk> wrote: > > Hi! > > On Fri, May 14, 2021 at 07:58:26AM -0400, Peter Geis wrote: > > + /* set rgmii delay mode */ > > + val = __phy_read(phydev, YT8511_PAGE); > > + > > + switch (phydev->interface) { > > + case PHY_INTERFACE_MODE_RGMII: > > + val &= ~(YT8511_DELAY_RX | YT8511_DELAY_TX); > > + break; > > + case PHY_INTERFACE_MODE_RGMII_ID: > > + val |= YT8511_DELAY_RX | YT8511_DELAY_TX; > > + break; > > + case PHY_INTERFACE_MODE_RGMII_RXID: > > + val &= ~(YT8511_DELAY_TX); > > + val |= YT8511_DELAY_RX; > > + break; > > + case PHY_INTERFACE_MODE_RGMII_TXID: > > + val &= ~(YT8511_DELAY_RX); > > + val |= YT8511_DELAY_TX; > > + break; > > + default: /* leave everything alone in other modes */ > > + break; > > + } > > + > > + ret = __phy_write(phydev, YT8511_PAGE, val); > > + if (ret < 0) > > + goto err_restore_page; > > Another way of writing the above is to set "val" to be the value of the > YT8511_DELAY_RX and YT8511_DELAY_TX bits, and then do: > > ret = __phy_modify(phydev, YT8511_PAGE, > (YT8511_DELAY_RX | YT8511_DELAY_TX), val); > if (ret < 0) > goto err_restore_page; > > which moves the read-modify-write out of the driver into core code and > makes the driver code smaller. It also handles your missing error check > on __phy_read() above - would you want the above code to attempt to > write a -ve error number back to this register? I suspect not!
That makes sense, thanks! I was thinking about how to use __phy_modify with a functional mask, but it didn't click until I had already sent it in. Also thanks for catching handling that ret on the read!
> > -- > RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ > FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
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