Hi,
On 04/19/2011 04:33 PM, ext Roger Quadros wrote:
Some USB function drivers (e.g. f_mass_storage.c) need to delay or defer the
status phase of standard control requests like SET_CONFIGURATION or
SET_INTERFACE till they are done with their bookkeeping and are actually ready
for accepting new commands to their interface.
They can now achieve this functionality by returning USB_GADGET_DELAYED_STATUS
in their setup handlers (e.g. set_alt()). The composite framework will then
defer completion of the setup transfer by not sending the Data/Status response.
This ensures that the host does not send new packets to the interface till the
function driver is ready to take them.
When the function driver that requested for USB_GADGET_DELAYED_STATUS is done
with its bookkeeping, it should signal the composite framework to continue with
the Data/Status phase of the setup transfer. It can do so by invoking
the new API usb_composite_setup_continue(). This is where the setup transfer's
data/status phases are completed and host can send new transfers.
The DELAYED_STATUS mechanism is currently only supported if the expected data phase
is 0 bytes (i.e. w_length == 0). Since SET_CONFIGURATION and SET_INTERFACE are the
only cases that will use this mechanism, this is not a limitation as such.
Signed-off-by: Roger Quadros<roger.quadros@xxxxxxxxx>
---
drivers/usb/gadget/composite.c | 61 +++++++++++++++++++++++++++++++++++++++-
include/linux/usb/composite.h | 17 ++++++++++-
2 files changed, 76 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 1ba4bef..43be36e 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -461,6 +461,15 @@ static int set_config(struct usb_composite_dev *cdev,
reset_config(cdev);
goto done;
}
+
+ if (result == USB_GADGET_DELAYED_STATUS) {
+ DBG(cdev,
+ "%s: interface %d (%s) requested delayed status\n",
+ __func__, tmp, f->name);
+ cdev->delayed_status++;
+ DBG(cdev, "delayed_status count %d\n",
+ cdev->delayed_status);
+ }
}
The below snippet needs to be added to the patch, else it causes a regression.
/* when we return, be sure our power usage is valid */
power = c->bMaxPower ? (2 * c->bMaxPower) : CONFIG_USB_GADGET_VBUS_DRAW;
done:
usb_gadget_vbus_draw(gadget, power);
+ if (result >= 0 && cdev->delayed_status)
+ result = USB_GADGET_DELAYED_STATUS;
return result;
}
I will fix this in the next version of the patch-set which I'll send soon.
--
regards,
-roger
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