linux-kernel - Re: [PATCH V2 2/2] MSP onchip root hub over current quirk.

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Date:	Thu, 23 Dec 2010 14:59:01 +0530
From:	Anoop P A <anoop.pa@...il.com>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Ralf Baechle <ralf@...ux-mips.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Anatolij Gustschin <agust@...x.de>,
	Anand Gadiyar <gadiyar@...com>, linux-mips@...ux-mips.org,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	Oliver Neukum <oneukum@...e.de>,
	Hans de Goede <hdegoede@...hat.com>,
	Paul Mortier <mortier@...nternet.com>,
	Andiry Xu <andiry.xu@....com>
Subject: Re: [PATCH V2 2/2] MSP onchip root hub over current quirk.

On Wed, 2010-12-22 at 21:18 -0500, Alan Stern wrote:
> On Wed, 22 Dec 2010, Anoop P.A wrote:
> 
> > From: Anoop P A <anoop.pa@...il.com>
> > 
> > Adding chip specific code under quirk.
> 
> NAK.  See below.
> 
> > Signed-off-by: Anoop P A <anoop.pa@...il.com>
> > ---
> >  drivers/usb/core/hub.c     |   45 ++++++++++++++++++++++++++++++++++++++-----
> >  drivers/usb/core/quirks.c  |    3 ++
> >  include/linux/usb/quirks.h |    3 ++
> >  3 files changed, 45 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> > index 27115b4..4bff994 100644
> > --- a/drivers/usb/core/hub.c
> > +++ b/drivers/usb/core/hub.c
> > @@ -3377,12 +3377,45 @@ static void hub_events(void)
> >  			}
> >  			
> >  			if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
> > -				dev_err (hub_dev,
> > -					"over-current change on port %d\n",
> > -					i);
> > -				clear_port_feature(hdev, i,
> > -					USB_PORT_FEAT_C_OVER_CURRENT);
> > -				hub_power_on(hub, true);
> > +				usb_detect_quirks(hdev);
> 
> This line is wrong.  usb_detect_quirks() gets called only once per 
> device, when the device is initialized.  Besides, you probably want to 
> use a hub-specific flag for this rather than a device-specific flag.

Can you point me to an example for the recommended way of doing the
hack. I don't have much exposure to USB subsystem.

> 
> > +				if (hdev->quirks & USB_QUIRK_MSP_OVERCURRENT) {
> 
> Also, it would be better to put this code in a separate subroutine 
> instead of indenting it so far.
> 
> > +					/* clear OCC bit */
> > +					clear_port_feature(hdev, i,
> > +						USB_PORT_FEAT_C_OVER_CURRENT);
> > +
> > +					/* This step is required to toggle the
> > +					* PP bit to 0 and 1 (by hub_power_on)
> > +					* in order the CSC bit to be
> > +					* transitioned properly for device
> > +					* hotplug
> > +					*/
> > +					/* clear PP bit */
> > +					clear_port_feature(hdev, i,
> > +						USB_PORT_FEAT_POWER);
> > +
> > +					/* resume power */
> > +					hub_power_on(hub, true);
> > +
> > +					/* delay 100 usec */
> > +					udelay(100);
> > +
> > +					/* read OCA bit */
> > +					if (portstatus &
> > +					(1<<USB_PORT_FEAT_OVER_CURRENT)) {
> > +						/* declare overcurrent */
> > +						dev_err(hub_dev,
> > +						"over-current change \
> > +							on port %d\n", i);
> > +					}
> > +				} else {
> > +					dev_err(hub_dev,
> > +						"over-current change \
> > +							on port %d\n", i);
> > +					clear_port_feature(hdev, i,
> > +						USB_PORT_FEAT_C_OVER_CURRENT);
> > +					hub_power_on(hub, true);
> > +				}
> > +
> >  			}
> >  
> >  			if (portchange & USB_PORT_STAT_C_RESET) {
> > diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
> > index 25719da..59843b9 100644
> > --- a/drivers/usb/core/quirks.c
> > +++ b/drivers/usb/core/quirks.c
> > @@ -88,6 +88,9 @@ static const struct usb_device_id usb_quirk_list[] = {
> >  	/* INTEL VALUE SSD */
> >  	{ USB_DEVICE(0x8086, 0xf1a5), .driver_info = USB_QUIRK_RESET_RESUME },
> >  
> > +	/* PMC MSP over current quirk */
> > +	{ USB_DEVICE(0x1d6b, 0x0002), .driver_info = USB_QUIRK_MSP_OVERCURRENT },
> > +
> 
> This implementation is completely wrong.  It applies to all USB-2.0
> root hubs in Linux, not just the PMC MSP.
> 
> >  	{ }  /* terminating entry must be last */
> >  };
> >  
> > diff --git a/include/linux/usb/quirks.h b/include/linux/usb/quirks.h
> > index 3e93de7..97ab168 100644
> > --- a/include/linux/usb/quirks.h
> > +++ b/include/linux/usb/quirks.h
> > @@ -30,4 +30,7 @@
> >     descriptor */
> >  #define USB_QUIRK_DELAY_INIT		0x00000040
> >  
> > +/*MSP SoC onchip EHCI overcurrent issue */
> > +#define USB_QUIRK_MSP_OVERCURRENT	0x00000080
> > +
> >  #endif /* __LINUX_USB_QUIRKS_H */
> > 
> 
Thanks
Anoop

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