linux-kernel - Re: [PATCH 3/7] phy: qcom-qmp-combo: Introduce orientation variable

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Message-ID: <ZFO21fLWSNc7orpb@hovoldconsulting.com>
Date:   Thu, 4 May 2023 15:44:53 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Bjorn Andersson <quic_bjorande@...cinc.com>
Cc:     Vinod Koul <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/7] phy: qcom-qmp-combo: Introduce orientation variable

On Wed, May 03, 2023 at 08:29:07PM -0700, Bjorn Andersson wrote:
> On Tue, May 02, 2023 at 01:48:16PM +0200, Johan Hovold wrote:
> > On Mon, Apr 24, 2023 at 08:40:06PM -0700, Bjorn Andersson wrote:

> > >  static void qmp_v3_dp_aux_init(struct qmp_combo *qmp);
> > > @@ -1955,29 +1962,23 @@ static void qmp_v3_configure_dp_tx(struct qmp_combo *qmp)
> > >  static bool qmp_combo_configure_dp_mode(struct qmp_combo *qmp)
> > >  {
> > >  	u32 val;
> > > -	bool reverse = false;
> > > +	bool reverse = qmp->orientation == TYPEC_ORIENTATION_REVERSE;

> > It also looks like these callbacks end up being called without holding
> > the qmp->phy_mutex via phy->power_on(). Perhaps there is no risk for a
> > concurrent switch notification and dp phy power-on but it's not that
> > obvious.

> It seems we're arriving here from hpd_event_thread(), while
> phy_power_on() and phy_power_off() will be called in some other context.
> I've not been able to convince myself if DP driver ensures ordering, or
> if we have an existing race here...

> Unless you insist, I would prefer to follow up with an additional patch
> once we've landed this series. The fix will depend on the phy_mutex
> shuffling patch anyways...

Sure.

But perhaps you can just move the orientation == qmp->orientation check
under the mutex in qmp_combo_typec_switch_set() for now (in case I
forgot to point that out earlier).

Johan