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Date:   Thu, 25 May 2023 19:55:54 -0700
From:   Bjorn Andersson <andersson@kernel.org>
To:     Krishna Kurapati <quic_kriskura@quicinc.com>
Cc:     Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Andy Gross <agross@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Felipe Balbi <balbi@kernel.org>, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        devicetree@vger.kernel.org, quic_pkondeti@quicinc.com,
        quic_ppratap@quicinc.com, quic_wcheng@quicinc.com,
        quic_jackp@quicinc.com, quic_harshq@quicinc.com,
        ahalaney@redhat.com
Subject: Re: [PATCH v8 6/9] usb: dwc3: qcom: Add multiport controller support
 for qcom wrapper
Message-ID: <20230526025554.ni527gsr2bqxadl3@ripper>
References: <20230514054917.21318-1-quic_kriskura@quicinc.com>
 <20230514054917.21318-7-quic_kriskura@quicinc.com>
 <20230515222730.7snn2i33gkg6ctd2@ripper>
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In-Reply-To: <20230515222730.7snn2i33gkg6ctd2@ripper>
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On Mon, May 15, 2023 at 03:27:30PM -0700, Bjorn Andersson wrote:
> On Sun, May 14, 2023 at 11:19:14AM +0530, Krishna Kurapati wrote:
> > QCOM SoC SA8295P's tertiary quad port controller supports 2 HS+SS
> > ports and 2 HS only ports. Add support for configuring PWR_EVENT_IRQ's
> > for all the ports during suspend/resume.
> > 
> > Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
> > ---
> >  drivers/usb/dwc3/dwc3-qcom.c | 28 ++++++++++++++++++++++------
> >  1 file changed, 22 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> > index 959fc925ca7c..7a9bce66295d 100644
> > --- a/drivers/usb/dwc3/dwc3-qcom.c
> > +++ b/drivers/usb/dwc3/dwc3-qcom.c
> > @@ -37,7 +37,10 @@
> >  #define PIPE3_PHYSTATUS_SW			BIT(3)
> >  #define PIPE_UTMI_CLK_DIS			BIT(8)
> >  
> > -#define PWR_EVNT_IRQ_STAT_REG			0x58
> > +#define PWR_EVNT_IRQ1_STAT_REG			0x58
> > +#define PWR_EVNT_IRQ2_STAT_REG			0x1dc
> > +#define PWR_EVNT_IRQ3_STAT_REG			0x228
> > +#define PWR_EVNT_IRQ4_STAT_REG			0x238
> >  #define PWR_EVNT_LPM_IN_L2_MASK			BIT(4)
> >  #define PWR_EVNT_LPM_OUT_L2_MASK		BIT(5)
> >  
> > @@ -93,6 +96,13 @@ struct dwc3_qcom {
> >  	struct icc_path		*icc_path_apps;
> >  };
> >  
> > +static u32 pwr_evnt_irq_stat_reg_offset[4] = {
> > +			PWR_EVNT_IRQ1_STAT_REG,
> > +			PWR_EVNT_IRQ2_STAT_REG,
> > +			PWR_EVNT_IRQ3_STAT_REG,
> > +			PWR_EVNT_IRQ4_STAT_REG,
> 
> Seems to be excessive indentation of these...
> 
> Can you also please confirm that these should be counted starting at 1 -
> given that you otherwise talk about port0..N-1?
> 
> > +};
> > +
> >  static inline void dwc3_qcom_setbits(void __iomem *base, u32 offset, u32 val)
> >  {
> >  	u32 reg;
> > @@ -413,13 +423,16 @@ static int dwc3_qcom_suspend(struct dwc3_qcom *qcom, bool wakeup)
> >  {
> >  	u32 val;
> >  	int i, ret;
> > +	struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
> >  
> >  	if (qcom->is_suspended)
> >  		return 0;
> >  
> > -	val = readl(qcom->qscratch_base + PWR_EVNT_IRQ_STAT_REG);
> > -	if (!(val & PWR_EVNT_LPM_IN_L2_MASK))
> > -		dev_err(qcom->dev, "HS-PHY not in L2\n");
> > +	for (i = 0; i < dwc->num_usb2_ports; i++) {
> 
> In the event that the dwc3 core fails to acquire or enable e.g. clocks
> its drvdata will be NULL. If you then hit a runtime pm transition in the
> dwc3-qcom glue you will dereference NULL here. (You can force this issue
> by e.g. returning -EINVAL from dwc3_clk_enable()).
> 

I looked at this once more, and realized that I missed the fact that
dwc3_qcom_is_host() will happily dereference the drvdata() just a few
lines further down...

So this is already broken.

> So if you're peaking into qcom->dwc3 you need to handle the fact that
> dwc might be NULL, here and in resume below.
> 

We need to fix the dwc3 glue design, so that the glue and the core can
cooperate - and we have a few other use cases where this is needed (e.g.
usb_role_switch propagation to the glue code).

Regards,
Bjorn

> Regards,
> Bjorn