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SubjectRe: [PATCH 01/20] net: phy: realtek: Fix events detection failure in LPI mode
Date
On 08.02.2021 15:03, Serge Semin wrote:
> It has been noticed that RTL8211E PHY stops detecting and reporting events
> when EEE is successfully advertised and RXC stopping in LPI is enabled.
> The freeze happens right after 3.0.10 bit (PC1R "Clock Stop Enable"
> register) is set. At the same time LED2 stops blinking as if EEE mode has
> been disabled. Notably the network traffic still flows through the PHY
> with no obvious problem. Anyway if any MDIO read procedure is performed
> after the "RXC stop in LPI" mode is enabled PHY gets to be unfrozen, LED2
> starts blinking and PHY interrupts happens again. The problem has been
> noticed on RTL8211E PHY working together with DW GMAC 3.73a MAC and
> reporting its event via a dedicated IRQ signal. (Obviously the problem has
> been unnoticed in the polling mode, since it gets naturally fixed by the
> periodic MDIO read procedure from the PHY status register - BMSR.)
>
> In order to fix that problem we suggest to locally re-implement the MMD
> write method for RTL8211E PHY and perform a dummy read right after the
> PC1R register is accessed to enable the RXC stopping in LPI mode.
>
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> ---
> drivers/net/phy/realtek.c | 37 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 37 insertions(+)
>
> diff --git a/drivers/net/phy/realtek.c b/drivers/net/phy/realtek.c
> index 99ecd6c4c15a..cbb86c257aae 100644
> --- a/drivers/net/phy/realtek.c
> +++ b/drivers/net/phy/realtek.c
> @@ -559,6 +559,42 @@ static int rtl822x_write_mmd(struct phy_device *phydev, int devnum, u16 regnum,
> return ret;
> }
>
> +static int rtl8211e_write_mmd(struct phy_device *phydev, int devnum, u16 regnum,
> + u16 val)
> +{
> + int ret;
> +
> + /* Write to the MMD registers by using the standard control/data pair.
> + * The only difference is that we need to perform a dummy read after
> + * the PC1R.CLKSTOP_EN bit is set. It's required to workaround an issue
> + * of a partial core freeze so LED2 stops blinking in EEE mode, PHY
> + * stops detecting the link change and raising IRQs until any read from
> + * its registers performed. That happens only if and right after the PHY
> + * is enabled to stop RXC in LPI mode.
> + */
> + ret = __phy_write(phydev, MII_MMD_CTRL, devnum);
> + if (ret)
> + return ret;
> +
> + ret = __phy_write(phydev, MII_MMD_DATA, regnum);
> + if (ret)
> + return ret;
> +
> + ret = __phy_write(phydev, MII_MMD_CTRL, devnum | MII_MMD_CTRL_NOINCR);
> + if (ret)
> + return ret;
> +

Nice analysis. Alternatively to duplicating this code piece we could
export mmd_phy_indirect(). But up to you.

> + ret = __phy_write(phydev, MII_MMD_DATA, val);
> + if (ret)
> + return ret;
> +
> + if (devnum == MDIO_MMD_PCS && regnum == MDIO_CTRL1 &&
> + val & MDIO_PCS_CTRL1_CLKSTOP_EN)
> + ret = __phy_read(phydev, MII_MMD_DATA);
> +
> + return ret < 0 ? ret : 0;
> +}
> +
> static int rtl822x_get_features(struct phy_device *phydev)
> {
> int val;
> @@ -725,6 +761,7 @@ static struct phy_driver realtek_drvs[] = {
> .resume = genphy_resume,
> .read_page = rtl821x_read_page,
> .write_page = rtl821x_write_page,
> + .write_mmd = rtl8211e_write_mmd,
> }, {
> PHY_ID_MATCH_EXACT(0x001cc916),
> .name = "RTL8211F Gigabit Ethernet",
>

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