One patch that was meant as a cleanup apparently did more than it intended,
allowing all combinations of legacy gadget drivers to be built into the
kernel, and leaving an empty 'choice' statement behind:
drivers/usb/gadget/Kconfig:487:warning: choice default symbol 'USB_ETH' is not contained in the choice
The description of commit 7a9618a22aad ("usb: gadget: allow to enable legacy
drivers without USB_ETH") was a bit cryptic, as it did not change the
behavior of USB_ETH other than allowing it to be built into the kernel
alongside other legacy gadgets, which is not a valid configuration.
As Felipe explained in the description for commit bc49d1d17dcf ("usb:
gadget: don't couple configfs to legacy gadgets"), the configfs based
gadgets can be freely configured as loadable modules or built-in
drivers, but the legacy gadgets can only be modules if there is more
than one of them, so we require the 'choice' statement here.
This leaves the added USB_GADGET_LEGACY menuconfig symbol in place,
but then restores the 'choice' below it, so we can enforce the
single-legacy-gadget rule as before.
Fixes: 7a9618a22aad ("usb: gadget: allow to enable legacy drivers without USB_ETH")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/usb/gadget/Kconfig | 28 ----------------------------
drivers/usb/gadget/legacy/Kconfig | 28 ++++++++++++++++++++++++++++
2 files changed, 28 insertions(+), 28 deletions(-)
diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 0a19a76645ad..eab61f552c19 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -482,34 +482,6 @@ config USB_CONFIGFS_F_TCM
Both protocols can work on USB2.0 and USB3.0.
UAS utilizes the USB 3.0 feature called streams support.
-choice
- tristate "USB Gadget precomposed configurations"
- default USB_ETH
- optional
- help
- A Linux "Gadget Driver" talks to the USB Peripheral Controller
- driver through the abstract "gadget" API. Some other operating
- systems call these "client" drivers, of which "class drivers"
- are a subset (implementing a USB device class specification).
- A gadget driver implements one or more USB functions using
- the peripheral hardware.
-
- Gadget drivers are hardware-neutral, or "platform independent",
- except that they sometimes must understand quirks or limitations
- of the particular controllers they work with. For example, when
- a controller doesn't support alternate configurations or provide
- enough of the right types of endpoints, the gadget driver might
- not be able work with that controller, or might need to implement
- a less common variant of a device class protocol.
-
- The available choices each represent a single precomposed USB
- gadget configuration. In the device model, each option contains
- both the device instantiation as a child for a USB gadget
- controller, and the relevant drivers for each function declared
- by the device.
-
-endchoice
-
source "drivers/usb/gadget/legacy/Kconfig"
endif # USB_GADGET
diff --git a/drivers/usb/gadget/legacy/Kconfig b/drivers/usb/gadget/legacy/Kconfig
index 9570bbeced4f..2d80a9d1d5d9 100644
--- a/drivers/usb/gadget/legacy/Kconfig
+++ b/drivers/usb/gadget/legacy/Kconfig
@@ -21,6 +21,32 @@ menuconfig USB_GADGET_LEGACY
if USB_GADGET_LEGACY
+choice
+ tristate "USB Gadget precomposed configurations"
+ default USB_ETH
+ optional
+ help
+ A Linux "Gadget Driver" talks to the USB Peripheral Controller
+ driver through the abstract "gadget" API. Some other operating
+ systems call these "client" drivers, of which "class drivers"
+ are a subset (implementing a USB device class specification).
+ A gadget driver implements one or more USB functions using
+ the peripheral hardware.
+
+ Gadget drivers are hardware-neutral, or "platform independent",
+ except that they sometimes must understand quirks or limitations
+ of the particular controllers they work with. For example, when
+ a controller doesn't support alternate configurations or provide
+ enough of the right types of endpoints, the gadget driver might
+ not be able work with that controller, or might need to implement
+ a less common variant of a device class protocol.
+
+ The available choices each represent a single precomposed USB
+ gadget configuration. In the device model, each option contains
+ both the device instantiation as a child for a USB gadget
+ controller, and the relevant drivers for each function declared
+ by the device.
+
config USB_ZERO
tristate "Gadget Zero (DEVELOPMENT)"
select USB_LIBCOMPOSITE
@@ -499,4 +525,6 @@ config USB_G_WEBCAM
Say "y" to link the driver statically, or "m" to build a
dynamically linked module called "g_webcam".
+endchoice
+
endif
--
2.9.0
Configuring the USB_G_WEBCAM driver as built-in leads to a link
error when CONFIG_VIDEO_V4L2 is a loadable module:
drivers/usb/gadget/function/f_uvc.o: In function `uvc_function_setup':
f_uvc.c:(.text+0xfe): undefined reference to `v4l2_event_queue'
drivers/usb/gadget/function/f_uvc.o: In function `uvc_function_ep0_complete':
f_uvc.c:(.text+0x188): undefined reference to `v4l2_event_queue'
This changes the Kconfig dependency to disallow that configuration,
and force it to be a module in that case as well.
This is apparently a rather old bug, but very hard to trigger
even in thousands of randconfig builds.
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/usb/gadget/legacy/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/legacy/Kconfig b/drivers/usb/gadget/legacy/Kconfig
index 2d80a9d1d5d9..fbd974965399 100644
--- a/drivers/usb/gadget/legacy/Kconfig
+++ b/drivers/usb/gadget/legacy/Kconfig
@@ -513,7 +513,7 @@ endif
# or video class gadget drivers), or specific hardware, here.
config USB_G_WEBCAM
tristate "USB Webcam Gadget"
- depends on VIDEO_DEV
+ depends on VIDEO_V4L2
select USB_LIBCOMPOSITE
select VIDEOBUF2_VMALLOC
select USB_F_UVC
--
2.9.0
On Mon, 2017-12-11 at 12:30 +0100, Arnd Bergmann wrote:
> One patch that was meant as a cleanup apparently did more than it intended,
> allowing all combinations of legacy gadget drivers to be built into the
> kernel, and leaving an empty 'choice' statement behind:
>
> drivers/usb/gadget/Kconfig:487:warning: choice default symbol 'USB_ETH' is not contained in the choice
>
> The description of commit 7a9618a22aad ("usb: gadget: allow to enable legacy
> drivers without USB_ETH") was a bit cryptic, as it did not change the
> behavior of USB_ETH other than allowing it to be built into the kernel
> alongside other legacy gadgets, which is not a valid configuration.
>
> As Felipe explained in the description for commit bc49d1d17dcf ("usb:
> gadget: don't couple configfs to legacy gadgets"), the configfs based
> gadgets can be freely configured as loadable modules or built-in
> drivers, but the legacy gadgets can only be modules if there is more
> than one of them, so we require the 'choice' statement here.
>
> This leaves the added USB_GADGET_LEGACY menuconfig symbol in place,
> but then restores the 'choice' below it, so we can enforce the
> single-legacy-gadget rule as before.
Hello Arnd,
A discussion is ongoing about whether or not commit 7a9618a22aad should be reverted.
Please drop this patch until a conclusion has been reached.
Thanks,
Bart.
On Mon, Dec 11, 2017 at 5:09 PM, Bart Van Assche <[email protected]> wrote:
> On Mon, 2017-12-11 at 12:30 +0100, Arnd Bergmann wrote:
>> One patch that was meant as a cleanup apparently did more than it intended,
>> allowing all combinations of legacy gadget drivers to be built into the
>> kernel, and leaving an empty 'choice' statement behind:
>>
>> drivers/usb/gadget/Kconfig:487:warning: choice default symbol 'USB_ETH' is not contained in the choice
>>
>> The description of commit 7a9618a22aad ("usb: gadget: allow to enable legacy
>> drivers without USB_ETH") was a bit cryptic, as it did not change the
>> behavior of USB_ETH other than allowing it to be built into the kernel
>> alongside other legacy gadgets, which is not a valid configuration.
>>
>> As Felipe explained in the description for commit bc49d1d17dcf ("usb:
>> gadget: don't couple configfs to legacy gadgets"), the configfs based
>> gadgets can be freely configured as loadable modules or built-in
>> drivers, but the legacy gadgets can only be modules if there is more
>> than one of them, so we require the 'choice' statement here.
>>
>> This leaves the added USB_GADGET_LEGACY menuconfig symbol in place,
>> but then restores the 'choice' below it, so we can enforce the
>> single-legacy-gadget rule as before.
>
> Hello Arnd,
>
> A discussion is ongoing about whether or not commit 7a9618a22aad should be reverted.
> Please drop this patch until a conclusion has been reached.
Ok. I'll use a revert of 7a9618a22aad in my local test tree then.
Reverting that is probably good, I thought about suggesting that
instead, but couldn't tell whether you had a bigger plan behind that
commit.
Arnd