Re: [PATCH V3 2/3] usb: dwc3: qcom: Add interconnect support in dwc3 driver

[Matthias Kaehlcke <mka@chromium.org>]

On Tue, Feb 04, 2020 at 11:05:41AM -0800, Evan Green wrote:
> Hi Chandana,
> Are you going to spin this series? My comments are below, I see
> Matthias also has comments. Please CC us both on the next spin.

v4 was actually posted a few days later:

https://patchwork.kernel.org/project/linux-usb/list/?series=176783

I also missed it since neither linux-arm-msm@ nor myself are in cc.

> On Tue, Sep 17, 2019 at 4:11 AM Chandana Kishori Chiluveru
> <cchiluve@codeaurora.org> 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: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>
> > ---
> >  drivers/usb/dwc3/dwc3-qcom.c | 145 ++++++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 143 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> > index 184df4d..2a2f5af 100644
> > --- a/drivers/usb/dwc3/dwc3-qcom.c
> > +++ b/drivers/usb/dwc3/dwc3-qcom.c
> > @@ -12,6 +12,7 @@
> >  #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>
> > @@ -59,8 +60,13 @@ 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);
> 
> Is there any reason you didn't just define these functions earlier?
> 
> > +
> >  static inline void dwc3_qcom_setbits(void __iomem *base, u32 offset, u32 val)
> >  {
> >         u32 reg;
> > @@ -222,7 +228,7 @@ 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;
> > @@ -234,6 +240,10 @@ 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);
> 
> Shouldn't you propagate the failure if this doesn't work?
> 
> > +
> >         qcom->is_suspended = true;
> >         dwc3_qcom_enable_interrupts(qcom);
> >
> > @@ -259,6 +269,10 @@ 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 here, isn't this important? In theory, if you cannot enable
> bandwidth to the device, you aren't really allowed to touch it (with
> odd exceptions for boot proxy votes, which might now be gone).
> 
> > +
> >         /* 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);
> > @@ -268,6 +282,124 @@ static int dwc3_qcom_resume(struct dwc3_qcom *qcom)
> >         return 0;
> >  }
> >
> > +/* 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)
> 
> Can you share at all how these numbers were arrived at? I thought HS
> for instance was 480MB/s.
> 
> > +
> > +/**
> > + * 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;
> > +
> > +       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);
> > +       }
> > +
> > +       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));
> 
> You're leaking usb_ddr_icc_path here.
> 
> > +               return PTR_ERR(qcom->apps_usb_icc_path);
> > +       }
> > +
> > +       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;
> > +       int ret;
> > +
> > +       dwc = platform_get_drvdata(qcom->dwc3);
> > +       if (!dwc) {
> > +               dev_err(qcom->dev, "Failed to get dwc3 device\n");
> > +               return -EPROBE_DEFER;
> > +       }
> > +
> > +       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);
> > +               if (ret)
> > +                       return ret;
> > +       } else {
> > +               ret = icc_set_bw(qcom->usb_ddr_icc_path,
> > +                       USB_MEMORY_AVG_HS_BW, USB_MEMORY_PEAK_HS_BW);
> > +               if (ret)
> > +                       return ret;
> > +       }
> > +
> > +       ret = icc_set_bw(qcom->apps_usb_icc_path,
> > +               APPS_USB_AVG_BW, APPS_USB_PEAK_BW);
> > +       if (ret)
> > +               goto err_disable_mem_path;
> > +
> > +       return 0;
> > +
> > +err_disable_mem_path:
> > +       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);
> 
> Yeah, this is weird. If you're failing to clear your votes, things are
> in a pretty broken state, and these calls to re-enable bandwidth have
> almost no chance of succeeding. Maybe just return failure here.
> 
> > +
> > +       return ret;
> > +}
> > +
> >  static irqreturn_t qcom_dwc3_resume_irq(int irq, void *data)
> >  {
> >         struct dwc3_qcom *qcom = data;
> > @@ -494,6 +626,12 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
> >                 goto depopulate;
> >         }
> >
> > +       ret = dwc3_qcom_interconnect_init(qcom);
> > +       if (ret) {
> > +               dev_err(dev, "failed to init interconnect handles %d\n", ret);
> > +               goto depopulate;
> > +       }
> > +
> >         qcom->mode = usb_get_dr_mode(&qcom->dwc3->dev);
> >
> >         /* enable vbus override for device mode */
> > @@ -503,7 +641,7 @@ 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;
> > @@ -513,6 +651,8 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
> >
> >         return 0;
> >
> > +interconnect_exit:
> > +       dwc3_qcom_interconnect_exit(qcom);
> >  depopulate:
> >         of_platform_depopulate(&pdev->dev);
> >  clk_disable:
> > @@ -540,6 +680,7 @@ 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);
> > --
> > Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.,
> > is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
> >