From: Ramneek Mehresh <ramneek.mehresh@freescale.com>
To: Alan Stern <stern@rowland.harvard.edu>
CC: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "balbi@ti.com" <balbi@ti.com>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        Li Leo <LeoLi@freescale.com>
Subject: RE: [PATCH 3/8][v2]usb:fsl:otg: Add support to add/remove usb host
 driver
Thread-Topic: [PATCH 3/8][v2]usb:fsl:otg: Add support to add/remove usb host
 driver
Thread-Index: AQHQvvR6ysWYVpVYJU+lfkTENAcEOp4BIr6AgAO57aA=
Date: Mon, 10 Aug 2015 09:23:09 +0000
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> -----Original Message-----
> From: Alan Stern [mailto:stern@rowland.harvard.edu]
> Sent: Saturday, August 08, 2015 2:04 AM
> To: Mehresh Ramneek-B31383
> Cc: linux-kernel@vger.kernel.org; balbi@ti.com;
> gregkh@linuxfoundation.org; linux-usb@vger.kernel.org; Li Yang-Leo-R58472
> Subject: Re: [PATCH 3/8][v2]usb:fsl:otg: Add support to add/remove usb
> host driver
> 
> On Wed, 15 Jul 2015, Ramneek Mehresh wrote:
> 
> > Add workqueue to add/remove host driver (outside interrupt context)
> > upon each id change.
> >
> > Signed-off-by: Li Yang <leoli@freescale.com>
> > Signed-off-by: Ramneek Mehresh <ramneek.mehresh@freescale.com>
> > ---
> >  drivers/usb/host/ehci-fsl.c | 83
> > ++++++++++++++++++++++++++++++++++-----------
> >  drivers/usb/host/ehci-fsl.h | 20 +++++++++++
> >  2 files changed, 84 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/usb/host/ehci-fsl.c b/drivers/usb/host/ehci-fsl.c
> > index 5352e74..81e4bf5 100644
> > --- a/drivers/usb/host/ehci-fsl.c
> > +++ b/drivers/usb/host/ehci-fsl.c
> > @@ -44,6 +44,34 @@
> >
> >  static struct hc_driver __read_mostly fsl_ehci_hc_driver;
> >
> > +#if defined(CONFIG_FSL_USB2_OTG) ||
> > +defined(CONFIG_FSL_USB2_OTG_MODULE)
> 
> You've got these #if lines all over the place.  They look ugly and make the
> code hard to read.  Consider removing them.  Or even if you can't remove
> them entirely, removing most of them would help.
> 
> Also, instead of testing both CONFIG_FSL_USB2_OTG and
> CONFIG_FSL_USB2_OTG_MODULE, how about testing a single symbol?  For
> example:
> 
> #if defined(CONFIG_FSL_USB2_OTG) ||
> defined(CONFIG_FSL_USB2_OTG_MODULE)
> #define CHANGE_HCD 1
> #else
> #define CHANGE_HCD 0
> #endif
> 
> Then all you need later on is "#if CHANGE_HCD".  Or if it's inside a code block,
> just "if (CHANGE_HCD)".
> 
Ok, let me see what can be done to minimize these macros. Thanks

> > +static struct ehci_fsl *hcd_to_ehci_fsl(struct usb_hcd *hcd) {
> > +	return (struct ehci_fsl *)hcd_to_ehci(hcd)->priv; }
> > +
> > +static void do_change_hcd(struct work_struct *work) {
> > +	struct ehci_fsl *ehci_fsl = container_of(work, struct ehci_fsl,
> > +					change_hcd_work);
> > +	struct usb_hcd *hcd = ehci_fsl->hcd;
> > +	void __iomem *non_ehci = hcd->regs;
> > +	int retval;
> > +
> > +	if (ehci_fsl->hcd_add && !ehci_fsl->have_hcd) {
> > +		writel(USBMODE_CM_HOST, non_ehci +
> FSL_SOC_USB_USBMODE);
> > +		/* host, gadget and otg share same int line */
> > +		retval = usb_add_hcd(hcd, hcd->irq, IRQF_SHARED);
> > +		if (retval == 0)
> > +			ehci_fsl->have_hcd = 1;
> > +	} else if (!ehci_fsl->hcd_add && ehci_fsl->have_hcd) {
> > +		usb_remove_hcd(hcd);
> > +		ehci_fsl->have_hcd = 0;
> 
> Don't you have to turn off the USBMODE_CM_HOST bit here?  It looks
> strange to turn it on above but not turn it off again.
> 
USBMODE bit defines mode for the controller. It gets auto cleared when controller is 
reset in host/gadget driver. After resetting, it's mandatory to write this bit once to define
controller's mode. 
> > +	}
> > +}
> > +#endif
> 
> 
> >  static int ehci_fsl_drv_suspend(struct device *dev)  {
> >  	struct usb_hcd *hcd = dev_get_drvdata(dev);
> > -	struct ehci_fsl *ehci_fsl = hcd_to_ehci_fsl(hcd);
> >  	void __iomem *non_ehci = hcd->regs;
> > +#if defined(CONFIG_FSL_USB2_OTG) ||
> defined(CONFIG_FSL_USB2_OTG_MODULE)
> > +	struct ehci_fsl *ehci_fsl = hcd_to_ehci_fsl(hcd);
> > +	struct usb_bus host = hcd->self;
> > +#endif
> > +
> >
> >  	if (of_device_is_compatible(dev->parent->of_node,
> >  				    "fsl,mpc5121-usb2-dr")) {
> >  		return ehci_fsl_mpc512x_drv_suspend(dev);
> >  	}
> >
> > +#if defined(CONFIG_FSL_USB2_OTG) ||
> defined(CONFIG_FSL_USB2_OTG_MODULE)
> > +	if (host.is_otg) {
> > +		/* remove hcd */
> > +		ehci_fsl->hcd_add = 0;
> > +		schedule_work(&ehci_fsl->change_hcd_work);
> > +		host.is_otg = 0;
> 
> Why do you set host.is_otg to 0 here?  Why not do it in the work routine?
Well, it can be done there also. I just wanted to keep host-bus house-keeping out
of otg role-changing specific workqueue (where host driver is brought-up/shut-down). 
> 
> > +		return 0;
> > +	}
> > +#endif
> > +
> >  	ehci_prepare_ports_for_controller_suspend(hcd_to_ehci(hcd),
> >  			device_may_wakeup(dev));
> >  	if (!fsl_deep_sleep())
> > @@ -540,15 +571,29 @@ static int ehci_fsl_drv_suspend(struct device
> > *dev)  static int ehci_fsl_drv_resume(struct device *dev)  {
> >  	struct usb_hcd *hcd = dev_get_drvdata(dev);
> > -	struct ehci_fsl *ehci_fsl = hcd_to_ehci_fsl(hcd);
> >  	struct ehci_hcd *ehci = hcd_to_ehci(hcd);
> >  	void __iomem *non_ehci = hcd->regs;
> > +#if defined(CONFIG_FSL_USB2_OTG) ||
> defined(CONFIG_FSL_USB2_OTG_MODULE)
> > +	struct ehci_fsl *ehci_fsl = hcd_to_ehci_fsl(hcd);
> > +	struct usb_bus host = hcd->self;
> > +#endif
> >
> >  	if (of_device_is_compatible(dev->parent->of_node,
> >  				    "fsl,mpc5121-usb2-dr")) {
> >  		return ehci_fsl_mpc512x_drv_resume(dev);
> >  	}
> >
> > +#if defined(CONFIG_FSL_USB2_OTG) ||
> defined(CONFIG_FSL_USB2_OTG_MODULE)
> > +	if (host.is_otg) {
> > +		/* add hcd */
> > +		ehci_fsl->hcd_add = 1;
> > +		schedule_work(&ehci_fsl->change_hcd_work);
> > +		usb_hcd_resume_root_hub(hcd);
> > +		host.is_otg = 0;
> 
> Again, why change host.is_otg here?  And for that matter, where does
> host.is_otg ever get set to 1?
host.is_otg sets to 1 in phy driver before calling ehci drv suspend/resume.
This is donr to make it clear in host drv suspend/resume that these functions
Are called in context of otg drv 
> 
> Also, what is the reason for calling usb_hcd_resume_root_hub()?  It won't
> do anything, because it will run before the scheduled work, so there won't
> be a root hub for it to resume.
> 
Well, you're right...it's not a surety that usb_hcd_resume_root_hub() will run after
scheduled work...i'll move it inside do_change_hcd() after usb_add_hcd(). Thanks.
> > +		return 0;
> > +	}
> > +#endif
> > +
> >  	ehci_prepare_ports_for_controller_resume(ehci);
> >  	if (!fsl_deep_sleep())
> >  		return 0;
> > diff --git a/drivers/usb/host/ehci-fsl.h b/drivers/usb/host/ehci-fsl.h
> > index dbd292e..3fd1fd0 100644
> > --- a/drivers/usb/host/ehci-fsl.h
> > +++ b/drivers/usb/host/ehci-fsl.h
> > @@ -62,4 +62,24 @@
> >  #define UTMI_PHY_EN             (1<<9)
> >  #define ULPI_PHY_CLK_SEL        (1<<10)
> >  #define PHY_CLK_VALID		(1<<17)
> > +
> > +struct ehci_fsl {
> > +#ifdef CONFIG_PM
> > +	/* Saved USB PHY settings, need to restore after deep sleep. */
> > +	u32 usb_ctrl;
> > +#endif
> > +	struct usb_hcd *hcd;
> > +#if defined(CONFIG_FSL_USB2_OTG) ||
> defined(CONFIG_FSL_USB2_OTG_MODULE)
> > +	struct work_struct change_hcd_work;
> > +#endif
> 
> Again, try to eliminate these #if's.  There really isn't anything wrong with
> allocating the space for these things even in a non-OTG build.
> 
> > +	/*
> > +	 * store current hcd state for otg;
> > +	 * have_hcd is true when host drv al already part of otg framework,
> > +	 * otherwise false;
> > +	 * hcd_add is true when otg framework wants to add host
> > +	 * drv as part of otg;flase when it wants to remove it
> > +	 */
> > +	unsigned have_hcd:1;
> > +	unsigned hcd_add:1;
> > +};
> >  #endif				/* _EHCI_FSL_H */
> 
> Alan Stern

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