netdev - Re: [PATCH net-next v3] net: ethernet: stmmac: dwmac-rk: Make the clk

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Message-ID: <aK19bSmrbXjoVXdO@shell.armlinux.org.uk>
Date: Tue, 26 Aug 2025 10:25:01 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Chaoyi Chen <chaoyi.chen@...k-chips.com>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>,
	Chaoyi Chen <kernel@...kyi.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Jonas Karlman <jonas@...boo.se>, David Wu <david.wu@...k-chips.com>,
	netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH net-next v3] net: ethernet: stmmac: dwmac-rk: Make the
 clk_phy could be used for external phy

On Tue, Aug 26, 2025 at 04:08:40PM +0800, Chaoyi Chen wrote:
> Hi Russell,
> 
> On 8/25/2025 9:37 PM, Russell King (Oracle) wrote:
> > On Mon, Aug 25, 2025 at 12:53:37PM +0200, Marek Szyprowski wrote:
> > > On 25.08.2025 11:57, Chaoyi Chen wrote:
> > > > On 8/25/2025 3:23 PM, Marek Szyprowski wrote:
> > > > > On 15.08.2025 04:35, Chaoyi Chen wrote:
> > > > > > From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
> > > > > > 
> > > > > > For external phy, clk_phy should be optional, and some external phy
> > > > > > need the clock input from clk_phy. This patch adds support for setting
> > > > > > clk_phy for external phy.
> > > > > > 
> > > > > > Signed-off-by: David Wu <david.wu@...k-chips.com>
> > > > > > Signed-off-by: Chaoyi Chen <chaoyi.chen@...k-chips.com>
> > > > > > ---
> > > > > > 
> > > > > > Changes in v3:
> > > > > > - Link to V2:
> > > > > > https://lore.kernel.org/netdev/20250812012127.197-1-kernel@airkyi.com/
> > > > > > - Rebase to net-next/main
> > > > > > 
> > > > > > Changes in v2:
> > > > > > - Link to V1:
> > > > > > https://lore.kernel.org/netdev/20250806011405.115-1-kernel@airkyi.com/
> > > > > > - Remove get clock frequency from DT prop
> > > > > > 
> > > > > >     drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c | 11 +++++++----
> > > > > >     1 file changed, 7 insertions(+), 4 deletions(-)
> > > > > > 
> > > > > > diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> > > > > > b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> > > > > > index ac8288301994..5d921e62c2f5 100644
> > > > > > --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> > > > > > +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> > > > > > @@ -1412,12 +1412,15 @@ static int rk_gmac_clk_init(struct
> > > > > > plat_stmmacenet_data *plat)
> > > > > >             clk_set_rate(plat->stmmac_clk, 50000000);
> > > > > >         }
> > > > > >     -    if (plat->phy_node && bsp_priv->integrated_phy) {
> > > > > > +    if (plat->phy_node) {
> > > > > >             bsp_priv->clk_phy = of_clk_get(plat->phy_node, 0);
> > > > > >             ret = PTR_ERR_OR_ZERO(bsp_priv->clk_phy);
> > > > > > -        if (ret)
> > > > > > -            return dev_err_probe(dev, ret, "Cannot get PHY clock\n");
> > > > > > -        clk_set_rate(bsp_priv->clk_phy, 50000000);
> > > > > > +        /* If it is not integrated_phy, clk_phy is optional */
> > > > > > +        if (bsp_priv->integrated_phy) {
> > > > > > +            if (ret)
> > > > > > +                return dev_err_probe(dev, ret, "Cannot get PHY
> > > > > > clock\n");
> > > > > > +            clk_set_rate(bsp_priv->clk_phy, 50000000);
> > > > > > +        }
> > > > I think  we should set bsp_priv->clk_phy to NULL here if we failed to
> > > > get the clock.
> > > > 
> > > > Could you try this on your board? Thank you.
> > > Right, the following change also fixes this issue:
> > > 
> > > diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> > > b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> > > index 9fc41207cc45..2d19d48be01f 100644
> > > --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> > > +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
> > > @@ -1415,6 +1415,8 @@ static int rk_gmac_clk_init(struct
> > > plat_stmmacenet_data *plat)
> > >           if (plat->phy_node) {
> > >                   bsp_priv->clk_phy = of_clk_get(plat->phy_node, 0);
> > >                   ret = PTR_ERR_OR_ZERO(bsp_priv->clk_phy);
> > > +               if (ret)
> > > +                       bsp_priv->clk_phy = NULL;
> > Or just:
> > 
> > 		clk = of_clk_get(plat->phy_node, 0);
> > 		if (clk == ERR_PTR(-EPROBE_DEFER))
> 
> Do we actually need this? Maybe other devm_clk_get() before it would fail in advance.

Is it the same clock as devm_clk_get()? If it is, what's the point of
getting it a second time. If it isn't, then it could be a different
clock which may be yet to probe.

-- 
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