linux-kernel - Re: [PATCH v8 6/9] usb: dwc3: qcom: Add multiport controller support for qcom wrapper

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Date:   Mon, 15 May 2023 15:27:30 -0700
From:   Bjorn Andersson <andersson@...nel.org>
To:     Krishna Kurapati <quic_kriskura@...cinc.com>
Cc:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Felipe Balbi <balbi@...nel.org>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, quic_pkondeti@...cinc.com,
        quic_ppratap@...cinc.com, quic_wcheng@...cinc.com,
        quic_jackp@...cinc.com, quic_harshq@...cinc.com,
        ahalaney@...hat.com
Subject: Re: [PATCH v8 6/9] usb: dwc3: qcom: Add multiport controller support
 for qcom wrapper

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@...cinc.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()).

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

Regards,
Bjorn