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Date:   Fri, 14 Feb 2020 12:11:54 -0800
From:   Matthias Kaehlcke <mka@chromium.org>
To:     Sandeep Maheswaram <sanm@codeaurora.org>
Cc:     Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Felipe Balbi <balbi@kernel.org>,
        Stephen Boyd <swboyd@chromium.org>,
        Doug Anderson <dianders@chromium.org>,
        linux-arm-msm@vger.kernel.org, linux-usb@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Manu Gautam <mgautam@codeaurora.org>,
        Chandana Kishori Chiluveru <cchiluve@codeaurora.org>
Subject: Re: [PATCH v5 2/3] usb: dwc3: qcom: Add interconnect support in dwc3
 driver
Message-ID: <20200214201154.GB15781@google.com>
References: <1581668684-4182-1-git-send-email-sanm@codeaurora.org>
 <1581668684-4182-3-git-send-email-sanm@codeaurora.org>
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Hi Sandeep,

On Fri, Feb 14, 2020 at 01:54:43PM +0530, Sandeep Maheswaram wrote:
> Add interconnect support in dwc3-qcom driver to vote for bus
> bandwidth.
> 
> This requires for two different paths - from USB master to
> DDR slave. The other is from APPS master to USB slave.
> 
> Signed-off-by: Sandeep Maheswaram <sanm@codeaurora.org>
> Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>
> ---
>  drivers/usb/dwc3/dwc3-qcom.c | 135 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 133 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index 261af9e..2ed6c20 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
> @@ -13,6 +13,7 @@
>  #include <linux/module.h>
>  #include <linux/kernel.h>
>  #include <linux/extcon.h>
> +#include <linux/interconnect.h>
>  #include <linux/of_platform.h>
>  #include <linux/platform_device.h>
>  #include <linux/phy/phy.h>
> @@ -43,6 +44,14 @@
>  #define SDM845_QSCRATCH_SIZE			0x400
>  #define SDM845_DWC3_CORE_SIZE			0xcd00
>  
> +/* Interconnect path bandwidths in MBps */
> +#define USB_MEMORY_AVG_HS_BW MBps_to_icc(240)
> +#define USB_MEMORY_PEAK_HS_BW MBps_to_icc(700)
> +#define USB_MEMORY_AVG_SS_BW  MBps_to_icc(1000)
> +#define USB_MEMORY_PEAK_SS_BW MBps_to_icc(2500)
> +#define APPS_USB_AVG_BW 0
> +#define APPS_USB_PEAK_BW MBps_to_icc(40)
> +
>  struct dwc3_acpi_pdata {
>  	u32			qscratch_base_offset;
>  	u32			qscratch_base_size;
> @@ -76,8 +85,13 @@ struct dwc3_qcom {
>  	enum usb_dr_mode	mode;
>  	bool			is_suspended;
>  	bool			pm_suspended;
> +	struct icc_path		*usb_ddr_icc_path;
> +	struct icc_path		*apps_usb_icc_path;
>  };
>  
> +static int dwc3_qcom_interconnect_enable(struct dwc3_qcom *qcom);
> +static int dwc3_qcom_interconnect_disable(struct dwc3_qcom *qcom);
> +
>  static inline void dwc3_qcom_setbits(void __iomem *base, u32 offset, u32 val)
>  {
>  	u32 reg;
> @@ -239,7 +253,7 @@ static void dwc3_qcom_enable_interrupts(struct dwc3_qcom *qcom)
>  static int dwc3_qcom_suspend(struct dwc3_qcom *qcom)
>  {
>  	u32 val;
> -	int i;
> +	int i, ret;
>  
>  	if (qcom->is_suspended)
>  		return 0;
> @@ -251,6 +265,10 @@ static int dwc3_qcom_suspend(struct dwc3_qcom *qcom)
>  	for (i = qcom->num_clocks - 1; i >= 0; i--)
>  		clk_disable_unprepare(qcom->clks[i]);
>  
> +	ret = dwc3_qcom_interconnect_disable(qcom);
> +	if (ret)
> +		dev_warn(qcom->dev, "failed to disable interconnect %d\n", ret);
> +

This assumes that all QCA systems with a DWC3 have an interconnect
configuration, however after applying this series SDM845 is the only
platform. You need to track somewhere if the controller in question has
an ICC config for not.

>  	qcom->is_suspended = true;
>  	dwc3_qcom_enable_interrupts(qcom);
>  
> @@ -276,6 +294,10 @@ static int dwc3_qcom_resume(struct dwc3_qcom *qcom)
>  		}
>  	}
>  
> +	ret = dwc3_qcom_interconnect_enable(qcom);
> +	if (ret)
> +		dev_warn(qcom->dev, "failed to enable interconnect %d\n", ret);
> +

same as above

>  	/* Clear existing events from PHY related to L2 in/out */
>  	dwc3_qcom_setbits(qcom->qscratch_base, PWR_EVNT_IRQ_STAT_REG,
>  			  PWR_EVNT_LPM_IN_L2_MASK | PWR_EVNT_LPM_OUT_L2_MASK);
> @@ -285,6 +307,108 @@ static int dwc3_qcom_resume(struct dwc3_qcom *qcom)
>  	return 0;
>  }
>  
> +
> +/**
> + * dwc3_qcom_interconnect_init() - Get interconnect path handles
> + * @qcom:			Pointer to the concerned usb core.
> + *
> + */
> +static int dwc3_qcom_interconnect_init(struct dwc3_qcom *qcom)
> +{
> +	struct device *dev = qcom->dev;
> +	int ret;
> +
> +	if (!device_is_bound(&qcom->dwc3->dev))
> +		return -EPROBE_DEFER;
> +
> +	qcom->usb_ddr_icc_path = of_icc_get(dev, "usb-ddr");
> +	if (IS_ERR(qcom->usb_ddr_icc_path)) {
> +		dev_err(dev, "Error: (%ld) failed getting usb-ddr path\n",
> +			PTR_ERR(qcom->usb_ddr_icc_path));
> +		return PTR_ERR(qcom->usb_ddr_icc_path);
> +	}

This will break all QCA platforms with DWC3, except SDM845. Instead of
failing you could interpret the basence of the 'usb-ddr' patch in the DT
as signal that the controller has no ICC configuration, and continue without
it (i.e. return 0 from here, don't print an error, at most a dev_info() log),
and track somewhere that the controller has no ICC config.

Alternatively you could check above with of_find_property() whether the
controller has an 'interconnects' property at all. If it doesn't exist
return zero, otherwise return an error if any of the paths doesn't exist,
as you do now.

> +
> +	qcom->apps_usb_icc_path = of_icc_get(dev, "apps-usb");
> +	if (IS_ERR(qcom->apps_usb_icc_path)) {
> +		dev_err(dev, "Error: (%ld) failed getting apps-usb path\n",
> +				PTR_ERR(qcom->apps_usb_icc_path));
> +		return PTR_ERR(qcom->apps_usb_icc_path);
> +	}

Failing here is ok, if 'usb-ddr' exists, we expect the rest of the config
to be in place.

> +
> +	ret = dwc3_qcom_interconnect_enable(qcom);
> +	if (ret) {
> +		dev_err(dev, "failed to enable interconnect %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * dwc3_qcom_interconnect_exit() - Release interconnect path handles
> + * @qcom:			Pointer to the concerned usb core.
> + *
> + * This function is used to release interconnect path handle.
> + */
> +static void dwc3_qcom_interconnect_exit(struct dwc3_qcom *qcom)
> +{
> +	icc_put(qcom->usb_ddr_icc_path);
> +	icc_put(qcom->apps_usb_icc_path);
> +}
> +
> +/* Currently we only use bandwidth level, so just "enable" interconnects */
> +static int dwc3_qcom_interconnect_enable(struct dwc3_qcom *qcom)
> +{
> +	struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
> +	int ret;
> +
> +	if (dwc->maximum_speed == USB_SPEED_SUPER) {
> +		ret = icc_set_bw(qcom->usb_ddr_icc_path,
> +			USB_MEMORY_AVG_SS_BW, USB_MEMORY_PEAK_SS_BW);
> +	} else {
> +		ret = icc_set_bw(qcom->usb_ddr_icc_path,
> +			USB_MEMORY_AVG_HS_BW, USB_MEMORY_PEAK_HS_BW);
> +	}

nit: curly braces are not needed here

> +
> +	if (ret)
> +		return ret;
> +
> +	ret = icc_set_bw(qcom->apps_usb_icc_path,
> +		APPS_USB_AVG_BW, APPS_USB_PEAK_BW);
> +	if (ret)
> +		icc_set_bw(qcom->usb_ddr_icc_path, 0, 0);
> +
> +	return ret;
> +}
> +
> +/* To disable an interconnect, we just set its bandwidth to 0 */
> +static int dwc3_qcom_interconnect_disable(struct dwc3_qcom *qcom)
> +{
> +	struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
> +	int ret;
> +
> +	ret = icc_set_bw(qcom->usb_ddr_icc_path, 0, 0);
> +	if (ret)
> +		return ret;
> +
> +	ret = icc_set_bw(qcom->apps_usb_icc_path, 0, 0);
> +	if (ret)
> +		goto err_reenable_memory_path;
> +
> +	return 0;
> +
> +	/* Re-enable things in the event of an error */
> +err_reenable_memory_path:
> +	if (dwc->maximum_speed == USB_SPEED_SUPER)
> +		icc_set_bw(qcom->usb_ddr_icc_path,
> +			USB_MEMORY_AVG_SS_BW, USB_MEMORY_PEAK_SS_BW);
> +	else
> +		icc_set_bw(qcom->usb_ddr_icc_path,
> +			USB_MEMORY_AVG_HS_BW, USB_MEMORY_PEAK_HS_BW);

instead of the above:

	dwc3_qcom_interconnect_enable(qcom);

> +
> +	return ret;
> +}
> +
>  static irqreturn_t qcom_dwc3_resume_irq(int irq, void *data)
>  {
>  	struct dwc3_qcom *qcom = data;
> @@ -648,6 +772,10 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>  		goto depopulate;
>  	}
>  
> +	ret = dwc3_qcom_interconnect_init(qcom);
> +	if (ret)
> +		goto depopulate;
> +
>  	qcom->mode = usb_get_dr_mode(&qcom->dwc3->dev);
>  
>  	/* enable vbus override for device mode */
> @@ -657,7 +785,7 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>  	/* register extcon to override sw_vbus on Vbus change later */
>  	ret = dwc3_qcom_register_extcon(qcom);
>  	if (ret)
> -		goto depopulate;
> +		goto interconnect_exit;
>  
>  	device_init_wakeup(&pdev->dev, 1);
>  	qcom->is_suspended = false;
> @@ -667,6 +795,8 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
>  
>  	return 0;
>  
> +interconnect_exit:
> +	dwc3_qcom_interconnect_exit(qcom);
>  depopulate:
>  	if (np)
>  		of_platform_depopulate(&pdev->dev);
> @@ -697,6 +827,7 @@ static int dwc3_qcom_remove(struct platform_device *pdev)
>  	}
>  	qcom->num_clocks = 0;
>  
> +	dwc3_qcom_interconnect_exit(qcom);
>  	reset_control_assert(qcom->resets);
>  
>  	pm_runtime_allow(dev);
> -- 
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>