linux-kernel - Re: [PATCH v11 2/5] usb: dwc3: core: Host wake up support from system suspend

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Message-ID: <20220405092557.GA15621@hu-pkondeti-hyd.qualcomm.com>
Date:   Tue, 5 Apr 2022 14:55:57 +0530
From:   Pavan Kondeti <quic_pkondeti@...cinc.com>
To:     Pavan Kondeti <quic_pkondeti@...cinc.com>
CC:     Sandeep Maheswaram <quic_c_sanm@...cinc.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi <balbi@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Doug Anderson <dianders@...omium.org>,
        "Matthias Kaehlcke" <mka@...omium.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        <linux-arm-msm@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <quic_ppratap@...cinc.com>,
        <quic_kriskura@...cinc.com>
Subject: Re: [PATCH v11 2/5] usb: dwc3: core: Host wake up support from
 system suspend

Hi Sandeep,

On Tue, Mar 22, 2022 at 02:02:21PM +0530, Pavan Kondeti wrote:
> Hi Sandeep,
> 
> On Tue, Mar 22, 2022 at 12:37:53PM +0530, Sandeep Maheswaram wrote:
> > During suspend read the status of all port and make sure the PHYs
> > are in the correct mode based on current speed.
> > Phy interrupt masks are set based on this mode. Keep track of the mode
> > of the HS PHY to be able to configure wakeup properly.
> > 
> > Also check during suspend if any wakeup capable devices are
> > connected to the controller (directly or through hubs), if there
> > are none set a flag to indicate that the PHY is powered
> > down during suspend.
> > 
> > Signed-off-by: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
> > ---
> >  drivers/usb/dwc3/core.c | 54 ++++++++++++++++++++++++++++++++++++++++---------
> >  1 file changed, 45 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > index 1170b80..232a734 100644
> > --- a/drivers/usb/dwc3/core.c
> > +++ b/drivers/usb/dwc3/core.c
> > @@ -32,12 +32,14 @@
> >  #include <linux/usb/gadget.h>
> >  #include <linux/usb/of.h>
> >  #include <linux/usb/otg.h>
> > +#include <linux/usb/hcd.h>
> >  
> >  #include "core.h"
> >  #include "gadget.h"
> >  #include "io.h"
> >  
> >  #include "debug.h"
> > +#include "../host/xhci.h"
> >  
> >  #define DWC3_DEFAULT_AUTOSUSPEND_DELAY	5000 /* ms */
> >  
> > @@ -1861,10 +1863,36 @@ static int dwc3_core_init_for_resume(struct dwc3 *dwc)
> >  	return ret;
> >  }
> >  
> > +static void dwc3_set_phy_speed_mode(struct dwc3 *dwc)
> > +{
> > +
> > +	int i, num_ports;
> > +	u32 reg;
> > +	struct usb_hcd	*hcd = platform_get_drvdata(dwc->xhci);
> > +	struct xhci_hcd	*xhci_hcd = hcd_to_xhci(hcd);
> > +
> > +	dwc->hs_phy_mode = 0;
> > +
> > +	reg = readl(&xhci_hcd->cap_regs->hcs_params1);
> > +
> > +	num_ports = HCS_MAX_PORTS(reg);
> > +	for (i = 0; i < num_ports; i++) {
> > +		reg = readl(&xhci_hcd->op_regs->port_status_base + i * 0x04);
> > +		if (reg & PORT_PE) {
> > +			if (DEV_HIGHSPEED(reg) || DEV_FULLSPEED(reg))
> > +				dwc->hs_phy_mode |= PHY_MODE_USB_HOST_HS;
> > +			else if (DEV_LOWSPEED(reg))
> > +				dwc->hs_phy_mode |= PHY_MODE_USB_HOST_LS;
> > +		}
> > +	}
> > +	phy_set_mode(dwc->usb2_generic_phy, dwc->hs_phy_mode);
> > +}
> 
> Are these flags cleared somewhere? Also qcom-snps-hs phy driver checks
> for (hsphy->mode == PHY_MODE_USB_HOST) condition in qcom_snps_hsphy_suspend
> to enable auto-resume. PHY_MODE_USB_HOST_HS/PHY_MODE_USB_HOST_LS flags
> are different from PHY_MODE_USB_HOST. Currently this flag is set from
> __dwc3_set_mode() when entering host mode. Can you clarify your intention
> in calling phy_set_mode() here.

I think re-purposing phy_set_mode() to override PHY_MODE_USB_HOST with
PHY_MODE_USB_HOST_HS/PHY_MODE_USB_HOST_LS might break other drivers. All
most all the phy drivers are checking against PHY_MODE_USB_HOST.

Why do we need to set phy_set_mode() here? The next patch in this series
only uses dwc->hs_phy_mode. can we drop phy_set_mode() call here?

Thanks,
Pavan