On Tue, Feb 04, 2020 at 01:06:59PM +0200, Lauri Jakku wrote:
> There is multiple reports of random behaviour of USB HID devices.
>
> I have mouse that acts sometimes quite randomly, I debugged with
> logs others have published: that there is HW timeouts that leave
> device in state that it is errorneus.
>
> To fix this, I introduce retry mechanism in root of USB HID drivers.
>
> Fix does not slow down operations at all if there is no -ETIMEDOUT
> got from control message sending.
>
> If there is one, then sleep 20ms and try again. Retry count is 20
> witch translates maximium of 400ms before giving up. If the 400ms
> boundary is reached the HW is really bad.
That's not even true. The caller passes in a timeout, in many cases 5
seconds, which you allow to expire up to 20 times on top of your
arbitrary 400 ms delay. So that's 100.4 seconds...
> JUST to be clear:
> This does not make USB HID devices to sleep anymore than
> before, if all is golden.
>
> Why modify usb-hid-core: No need to modify driver by driver.
Because you cannot decide how every use should handle timeouts.
Just fix up the driver that needs this.
> Signed-off-by: Lauri Jakku <lja@xxxxxx>
> ---
> drivers/usb/core/message.c | 30 +++++++++++++++++++++++++-----
> 1 file changed, 25 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
> index 5adf489428aa..b375e376ea22 100644
> --- a/drivers/usb/core/message.c
> +++ b/drivers/usb/core/message.c
> @@ -20,6 +20,7 @@
> #include <linux/usb/hcd.h> /* for usbcore internals */
> #include <linux/usb/of.h>
> #include <asm/byteorder.h>
> +#include <linux/errno.h>
>
> #include "usb.h"
>
> @@ -137,7 +138,10 @@ int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
> __u16 size, int timeout)
> {
> struct usb_ctrlrequest *dr;
> - int ret;
> + int ret = -ETIMEDOUT;
> +
> + /* retry_cnt * 20ms, max retry time set to 400ms */
> + int retry_cnt = 20;
>
> dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_NOIO);
> if (!dr)
> @@ -149,11 +153,27 @@ int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
> dr->wIndex = cpu_to_le16(index);
> dr->wLength = cpu_to_le16(size);
>
> - ret = usb_internal_control_msg(dev, pipe, dr, data, size, timeout);
> + do {
> + ret = usb_internal_control_msg(dev,
> + pipe,
> + dr,
> + data,
> + size,
> + timeout);
> +
> + /*
> + * Linger a bit, prior to the next control message
> + * or if return value is timeout, but do try few
> + * times (max 400ms) before quitting.
> + */
> + if (dev->quirks & USB_QUIRK_DELAY_CTRL_MSG)
> + msleep(200);
> + else if (ret == -ETIMEDOUT)
> + msleep(20);
> +
> + /* Loop while timeout, max loops: retry_cnt times. */
> + } while ((retry_cnt-- > 0) && (ret == -ETIMEDOUT));
>
> - /* Linger a bit, prior to the next control message. */
> - if (dev->quirks & USB_QUIRK_DELAY_CTRL_MSG)
> - msleep(200);
>
> kfree(dr);
Johan
