Re: [PATCH] usb: core: Add "quirks" parameter for usbcore

[Oliver Neukum]

Am Mittwoch, den 06.12.2017, 17:09 +0800 schrieb Kai-Heng Feng:
> Now users can use "usbcore.quirks=" as short term workaround before the
> next kernel release.
> 
> This is inspired by usbhid and usb-storage.

Hi,

if you include this for debugging purposes, it would be interesting
to be able to not only switch on a quirk from the command line, but
to also switch it off. So it might be better to detect the dynamic
quirks after the static quirks and use XOR.

Regards
Oliver

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Re: [PATCH] usb: core: Add "quirks" parameter for usbcore

[Kai Heng Feng]

> On 6 Dec 2017, at 5:13 PM, Greg KH  wrote:
> 
> On Wed, Dec 06, 2017 at 05:09:32PM +0800, Kai-Heng Feng wrote:
>> +/* Works only for digits and letters, but small and fast */
>> +#define TOLOWER(x) ((x) | 0x20)
> 
> What is wrong with the in-kernel version of tolower()?

Nothing’s wrong with the in-kernel version. I’ll use that in v2.

Other than that, is there anythings I can make to improve the code?

Kai-Heng

> 
> thanks,
> 
> greg k-h

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Re: [PATCH] usb: core: Add "quirks" parameter for usbcore

[Greg KH]

On Wed, Dec 06, 2017 at 05:09:32PM +0800, Kai-Heng Feng wrote:
> +/* Works only for digits and letters, but small and fast */
> +#define TOLOWER(x) ((x) | 0x20)

What is wrong with the in-kernel version of tolower()?

thanks,

greg k-h
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[PATCH] usb: core: Add "quirks" parameter for usbcore

[Kai-Heng Feng]

Trying quirks in usbcore needs to rebuild the driver or the entire
kernel if it's builtin. It can save a lot of time if usbcore has similar
ability like "usbhid.quirks=" and "usb-storage.quirks=".

Rename the original quirk detection function to "static" as we introduce
this new "dynamic" function.

Now users can use "usbcore.quirks=" as short term workaround before the
next kernel release.

This is inspired by usbhid and usb-storage.

Signed-off-by: Kai-Heng Feng 
---
 Documentation/admin-guide/kernel-parameters.txt |  55 +
 drivers/usb/core/quirks.c   | 103 ++--
 include/linux/usb/quirks.h  |   2 +
 3 files changed, 154 insertions(+), 6 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt 
b/Documentation/admin-guide/kernel-parameters.txt
index 6571fbfdb2a1..f1cb31aa25e3 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4302,6 +4302,61 @@
 
usbcore.nousb   [USB] Disable the USB subsystem
 
+   usbcore.quirks=
+   [USB] A list of quirks entries to supplement or
+   override the built-in usb core quirk list.  List
+   entries are separated by commas.  Each entry has
+   the form VID:PID:Flags where VID and PID are Vendor
+   and Product ID values (4-digit hex numbers) and
+   Flags is a set of characters, each corresponding
+   to a common usb core quirk flag as follows:
+   a = USB_QUIRK_STRING_FETCH_255 (string
+   descriptors must not be fetched using
+   a 255-byte read);
+   b = USB_QUIRK_RESET_RESUME (device can't resume
+   correctly so reset it instead);
+   c = USB_QUIRK_NO_SET_INTF (device can't handle
+   Set-Interface requests);
+   d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't
+   handle its Configuration or Interface
+   strings);
+   e = USB_QUIRK_RESET (device can't be reset
+   (e.g morph devices), don't use reset);
+   f = USB_QUIRK_HONOR_BNUMINTERFACES (device has
+   more interface descriptions than the
+   bNumInterfaces count, and can't handle
+   talking to these interfaces);
+   g = USB_QUIRK_DELAY_INIT (device needs a pause
+   during initialization, after we read
+   the device descriptor);
+   h = USB_QUIRK_LINEAR_UFRAME_INTR_BINTERVAL (For
+   high speed and super speed interrupt
+   endpoints, the USB 2.0 and USB 3.0 spec
+   require the interval in microframes (1
+   microframe = 125 microseconds) to be
+   calculated as interval = 2 ^
+   (bInterval-1).
+   Devices with this quirk report their
+   bInterval as the result of this
+   calculation instead of the exponent
+   variable used in the calculation);
+   i = USB_QUIRK_DEVICE_QUALIFIER (device can't
+   handle device_qualifier descriptor
+   requests);
+   j = USB_QUIRK_IGNORE_REMOTE_WAKEUP (device
+   generates spurious wakeup, ignore
+   remote wakeup capability);
+   k = USB_QUIRK_NO_LPM (device can't handle Link
+   Power Management);
+   l = USB_QUIRK_LINEAR_FRAME_INTR_BINTERVAL
+   (Device reports its bInterval as linear
+   frames instead of the USB 2.0
+   calculation);
+   m = USB_QUIRK_DISCONNECT_SUSPEND (Device needs
+   to be disconnected before suspend to
+   prevent spurious wakeup)
+   Example: quirks=0781:5580:bk,0a5c:5834:gij
+
usbhid.mousepoll=