Re: [PATCH] net: stmmac: disable/enable ptp_ref_clk in suspend/resume flow

From: Jakub Kicinski
Date: Thu Oct 10 2019 - 19:01:25 EST


On Wed, 9 Oct 2019 16:56:49 +0800, Biao Huang wrote:
> disable ptp_ref_clk in suspend flow, and enable it in resume flow.
>
> Signed-off-by: Biao Huang <biao.huang@xxxxxxxxxxxx>
> ---
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index c7c9e5f162e6..b592aeecc3dd 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -4469,6 +4469,8 @@ int stmmac_suspend(struct device *dev)
> stmmac_mac_set(priv, priv->ioaddr, false);
> pinctrl_pm_select_sleep_state(priv->device);
> /* Disable clock in case of PWM is off */
> + if (priv->plat->clk_ptp_ref)
> + clk_disable_unprepare(priv->plat->clk_ptp_ref);

I don't know much embedded, but it seems like this should perhaps just
be clk_disable() without the unprepare? stmmac_hw_teardown() is called
when driver is removed so it needs to unprepare as well.

Please feel free to explain to me why this needs to be
clk_disable_unprepare(), as I said - not an expert.

Also - if this is a bug fix and you'd like to have it backported to
older releases you need to add a Fixes tag.

Thanks!

> clk_disable(priv->plat->pclk);
> clk_disable(priv->plat->stmmac_clk);
> }
> @@ -4535,6 +4537,8 @@ int stmmac_resume(struct device *dev)
> /* enable the clk previously disabled */
> clk_enable(priv->plat->stmmac_clk);
> clk_enable(priv->plat->pclk);
> + if (priv->plat->clk_ptp_ref)
> + clk_prepare_enable(priv->plat->clk_ptp_ref);
> /* reset the phy so that it's ready */
> if (priv->mii)
> stmmac_mdio_reset(priv->mii);