linux-kernel - Re: [PATCH] usb: typec: qcom-pmic-typec: split HPD bridge alloc and registration

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Message-ID: <CAA8EJprybRaxMGHW+bAm5SriKNJYjWYHAok+je=Q4SjGV0iDfw@mail.gmail.com>
Date: Mon, 8 Apr 2024 01:47:09 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: "Bryan O'Donoghue" <bryan.odonoghue@...aro.org>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konrad.dybcio@...aro.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Caleb Connolly <caleb.connolly@...aro.org>, 
	Johan Hovold <johan+linaro@...nel.org>
Subject: Re: [PATCH] usb: typec: qcom-pmic-typec: split HPD bridge alloc and registration

On Sun, 7 Apr 2024 at 22:32, Bryan O'Donoghue
<bryan.odonoghue@...aro.org> wrote:
>
> On 07/04/2024 16:08, Dmitry Baryshkov wrote:
> > Basically, if for some reason (e.g. because the TCPM returns an error
> > to one of the start functions) the drm_bridge is destroyed, the DRM
> > driver isn't notified about the event. It still keeps the pointer to
> > the bridge pointer and can access freed memory afterwards.
>
> Hmm, my concern/question is about the TCPM code triggered by an IRQ
> firing here, racing with the bridge code.

There is no actual race. In the worst case scenario, the TCPM will
bring up the DP altmode and the altmode driver will send an OOB HPD
event. However as this is an OOB event, the DRM subsystem correctly
handles the case if there is no corresponding connector.

> If you're happy you've reasoned about that and it won't happen, then
> apply the ACK with the commit log fixed alone.

Thanks!


-- 
With best wishes
Dmitry