linux-kernel - Re: [PATCH net-next 2/2] net: stmmac: platform: add support for phy-supply

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Message-ID: <20230718131556.bdp3sykrkkylp4pb@pengutronix.de>
Date:   Tue, 18 Jul 2023 15:15:56 +0200
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        peppe.cavallaro@...com, alexandre.torgue@...s.st.com,
        joabreu@...opsys.com, mcoquelin.stm32@...il.com,
        netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, kernel@...gutronix.de
Subject: Re: [PATCH net-next 2/2] net: stmmac: platform: add support for
 phy-supply

On 23-07-18, Andrew Lunn wrote:
> On Tue, Jul 18, 2023 at 10:35:04AM +0200, Marco Felsch wrote:
> > On 23-07-18, Andrew Lunn wrote:
> > > On Mon, Jul 17, 2023 at 06:43:07PM +0200, Marco Felsch wrote:
> > > > Add generic phy-supply handling support to control the phy regulator.
> > > > Use the common stmmac_platform code path so all drivers using
> > > > stmmac_probe_config_dt() and stmmac_pltfr_pm_ops can use it.
> > > > 
> > > > Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
> > > > ---
> > > >  .../ethernet/stmicro/stmmac/stmmac_platform.c | 51 +++++++++++++++++++
> > > >  include/linux/stmmac.h                        |  1 +
> > > >  2 files changed, 52 insertions(+)
> > > > 
> > > > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> > > > index eb0b2898daa3d..6193d42b53fb7 100644
> > > > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> > > > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> > > > @@ -10,6 +10,7 @@
> > > >  
> > > >  #include <linux/platform_device.h>
> > > >  #include <linux/pm_runtime.h>
> > > > +#include <linux/regulator/consumer.h>
> > > >  #include <linux/module.h>
> > > >  #include <linux/io.h>
> > > >  #include <linux/of.h>
> > > > @@ -423,6 +424,15 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac)
> > > >  	if (plat->interface < 0)
> > > >  		plat->interface = plat->phy_interface;
> > > >  
> > > > +	/* Optional regulator for PHY */
> > > > +	plat->phy_regulator = devm_regulator_get_optional(&pdev->dev, "phy");
> > > > +	if (IS_ERR(plat->phy_regulator)) {
> > > > +		if (PTR_ERR(plat->phy_regulator) == -EPROBE_DEFER)
> > > > +			return ERR_CAST(plat->phy_regulator);
> > > > +		dev_info(&pdev->dev, "No regulator found\n");
> > > > +		plat->phy_regulator = NULL;
> > > > +	}
> > > > +
> > > 
> > > So this gets the regulator. When do you actually turn it on?
> > 
> > During the suspend/resume logic like the rockchip, sun8i platform
> > integrations did.
> 
> So you are assuming the boot loader has turned it on?
> 
> You also might have a difference between the actual state, and what
> kernel thinks the state is, depending on how the regulator is
> implemented.
> 
> It would be better to explicitly turn it on before registering the
> MDIO bus.

You're right, I changed this. Thanks for the hint.

Regards,
  Marco