linux-kernel - Re: [PATCH net] net: stmmac: dwmac-rk: Ensure clk

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Message-ID: <5d691f5b-460e-46cb-9658-9c391058342f@rock-chips.com>
Date: Sat, 6 Sep 2025 14:26:31 +0800
From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
To: Yao Zi <ziyao@...root.org>, "Russell King (Oracle)"
 <linux@...linux.org.uk>
Cc: 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>,
 Jonas Karlman <jonas@...boo.se>, David Wu <david.wu@...k-chips.com>,
 netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH net] net: stmmac: dwmac-rk: Ensure clk_phy doesn't contain
 invalid address

On 9/6/2025 1:36 PM, Yao Zi wrote:

> On Thu, Sep 04, 2025 at 12:07:26PM +0100, Russell King (Oracle) wrote:
>> On Thu, Sep 04, 2025 at 12:05:19PM +0100, Russell King (Oracle) wrote:
>>> On Thu, Sep 04, 2025 at 07:03:10PM +0800, Chaoyi Chen wrote:
>>>> On 9/4/2025 6:58 PM, Russell King (Oracle) wrote:
>>>>> On Thu, Sep 04, 2025 at 03:12:24AM +0000, Yao Zi wrote:
>>>>>>    	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 it is not integrated_phy, clk_phy is optional */
>>>>>> +		/*
>>>>>> +		 * If it is not integrated_phy, clk_phy is optional. But we must
>>>>>> +		 * set bsp_priv->clk_phy to NULL if clk_phy isn't proivded, or
>>>>>> +		 * the error code could be wrongly taken as an invalid pointer.
>>>>>> +		 */
>>>>> I'm concerned by this. This code is getting the first clock from the DT
>>>>> description of the PHY. We don't know what type of PHY it is, or what
>>>>> the DT description of that PHY might suggest that the first clock would
>>>>> be.
>>>>>
>>>>> However, we're geting it and setting it to 50MHz. What if the clock is
>>>>> not what we think it is?
>>>> We only set integrated_phy to 50M, which are all known targets. For external PHYs, we do not perform frequency settings.
>>> Same question concerning enabling and disabling another device's clock
>>> that the other device should be handling.
>> Let me be absolutely clear: I consider *everything* that is going on
>> with clk_phy here to be a dirty hack.
>>
>> Resources used by a device that has its own driver should be managed
>> by _that_ driver alone, not by some other random driver.
> Agree on this. Should we drop the patch, or fix it up for now to at
> least prevent the oops? Chaoyi, I guess there's no user of the feature
> for now, is it?

This at least needs fixing. Sorry, I have no idea how to implement this in the PHY.