renegade-project/linux-next
2
0
Fork 0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-19 18:53:52 +08:00
Code

usb: dwc3: gadget: let us set lower max_speed

Browse Source 
In some SoCs, dwc3 is implemented as a USB2.0 only
core, meaning that it can't ever achieve SuperSpeed.

Currect driver always sets gadget.max_speed to
USB_SPEED_SUPER unconditionally. This can causes
issues to some Host stacks where the host will issue
a GetBOS() request and we will reply with a BOS
containing Superspeed Capability Descriptor.

At least Windows seems to be upset by this fact and
prints a warning that we should connect $this device
to another port.

[ balbi@ti.com : rewrote entire commit, including
source code comment to make a lot clearer what the
problem is ]

Cc: <stable@vger.kernel.org>
Signed-off-by: Ben McCauley <ben.mccauley@garmin.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
This commit is contained in:
Ben McCauley 2015-11-16 10:47:24 -06:00 committed by Felipe Balbi
parent 68fe05e2a4
commit b9e51b2b1f
1 changed files with 23 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
drivers/usb/dwc3/gadget.c
View File

@ -2744,11 +2744,33 @@ int dwc3_gadget_init(struct dwc3 *dwc)
}
dwc->gadget.ops = &dwc3_gadget_ops;
dwc->gadget.max_speed = USB_SPEED_SUPER;
dwc->gadget.speed = USB_SPEED_UNKNOWN;
dwc->gadget.sg_supported = true;
dwc->gadget.name = "dwc3-gadget";
/*
* FIXME We might be setting max_speed to <SUPER, however versions
* <2.20a of dwc3 have an issue with metastability (documented
* elsewhere in this driver) which tells us we can't set max speed to
* anything lower than SUPER.
*
* Because gadget.max_speed is only used by composite.c and function
* drivers (i.e. it won't go into dwc3's registers) we are allowing this
* to happen so we avoid sending SuperSpeed Capability descriptor
* together with our BOS descriptor as that could confuse host into
* thinking we can handle super speed.
*
* Note that, in fact, we won't even support GetBOS requests when speed
* is less than super speed because we don't have means, yet, to tell
* composite.c that we are USB 2.0 + LPM ECN.
*/
if (dwc->revision < DWC3_REVISION_220A)
dwc3_trace(trace_dwc3_gadget,
"Changing max_speed on rev %08x\n",
dwc->revision);
dwc->gadget.max_speed = dwc->maximum_speed;
/*
* Per databook, DWC3 needs buffer size to be aligned to MaxPacketSize
* on ep out.