linux-kernel - Re: [PATCH v2] phy: use per-PHY lockdep keys

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Message-ID: <aEBAMUdAVPB+cN78@linaro.org>
Date: Wed, 4 Jun 2025 15:46:41 +0300
From: Abel Vesa <abel.vesa@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Vinod Koul <vkoul@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] phy: use per-PHY lockdep keys

On 25-05-30 19:08:28, Dmitry Baryshkov wrote:
> If the PHY driver uses another PHY internally (e.g. in case of eUSB2,
> repeaters are represented as PHYs), then it would trigger the following
> lockdep splat because all PHYs use a single static lockdep key and thus
> lockdep can not identify whether there is a dependency or not and
> reports a false positive.
> 
> Make PHY subsystem use dynamic lockdep keys, assigning each driver a
> separate key. This way lockdep can correctly identify dependency graph
> between mutexes.
> 

[...]

> 
> Fixes: 3584f6392f09 ("phy: qcom: phy-qcom-snps-eusb2: Add support for eUSB2 repeater")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>

I'm OK with this as a temporary workaround, at least until we figure out
a way to have chained PHYs in the generic framework. I think long-term,
the PHY framework should be the one to call the ops of the child PHY on
behalf of the parent.

For now, this LGTM:
Reviewed-by: Abel Vesa <abel.vesa@...aro.org>