Thread (14 messages) flat view 14 messages, 4 authors, 2021-06-02

RE: [PATCH net-next 3/4] net: phy: realteck: add dt property to disable ALDPS mode

From: Joakim Zhang <hidden>
Date: 2021-06-02 02:23:02
Also in: lkml, netdev

Hi Russell,
-----Original Message-----
From: Russell King <linux@armlinux.org.uk>
Sent: 2021年6月1日 19:52
To: Joakim Zhang <redacted>
Cc: davem@davemloft.net; kuba@kernel.org; robh+dt@kernel.org;
andrew@lunn.ch; hkallweit1@gmail.com; f.fainelli@gmail.com; dl-linux-imx
[off-list ref]; netdev@vger.kernel.org; devicetree@vger.kernel.org;
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 3/4] net: phy: realteck: add dt property to disable
ALDPS mode

On Tue, Jun 01, 2021 at 05:04:07PM +0800, Joakim Zhang wrote:
quoted
@@ -325,8 +329,10 @@ static int rtl8211f_config_init(struct phy_device
*phydev)
quoted
 	u16 val;
 	int ret;

-	val = RTL8211F_ALDPS_ENABLE | RTL8211F_ALDPS_PLL_OFF |
RTL8211F_ALDPS_XTAL_OFF;
quoted
-	phy_modify_paged_changed(phydev, 0xa43, RTL8211F_PHYCR1, val, val);
+	if (!(priv->quirks & RTL821X_ALDPS_DISABLE_FEATURE)) {
+		val = RTL8211F_ALDPS_ENABLE | RTL8211F_ALDPS_PLL_OFF |
RTL8211F_ALDPS_XTAL_OFF;
quoted
+		phy_modify_paged_changed(phydev, 0xa43, RTL8211F_PHYCR1, val,
val);
quoted
+	}
Similar questions as with the previous patch, but also... this doesn't actually
disable the feature if it was previously turned on. E.g. a
kexec() from a current kernel that has set these features into a subsequent
kernel that the DT requests the feature to be disabled. Or a boot loader that
has enabled this feature.
Sorry, I don't know what your meanings. As I explained before, boot loader also can configure PHY registers,
but kernel should not depend on what boot loader did.

If you use kexec() to boot kernel with DT request to disable this clock, PHY probe also can parse this property to disable it.
I know little about kexec(), could you please explain more if I misunderstand?
If DT specifies that this feature is disabled, shouldn't this code be disabling it
explicitly?
Yes, exactly should.

Best Regards,
Joakim Zhang
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