Appreciate your comments! On Thu, 2019-10-10 at 16:01 -0700, Jakub Kicinski wrote: > 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.hu...@mediatek.com> > > --- > > 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. > As our clock owner's advice, there are prepare/unprepare clk_ops for pll, but no enable/disable clk_ops for it, and pll will be off only when the prepare reference count decrease to 0.
so for the sake of power saving, we'd better call clk_disable_unprepare to turn the parent pll off. > 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 for the reminder, I'll add the fixes tag in the next version. > Thanks! > > > clk_disable(priv->plat->pclk); > > clk_disable(priv->plat->stmmac_clk); maybe it should be clk_disable_unprepare(priv->plat->pclk); clk_disable_unprepare(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); >