2017-09-05 08:41:48

by Dmitry Fleytman

Subject: [PATCH] usb: Increase quirk delay for USB devices

Commit e0429362ab15
("usb: Add device quirk for Logitech HD Pro Webcams C920 and C930e")
introduced quirk to workaround an issue with some Logitech webcams.

The workaround is introducing delay for some USB operations.

According to our testing, delay introduced by original commit
is not long enough and in rare cases we still see issues described
by the aforementioned commit.

This patch increases delays introduced by original commit.
Having this patch applied we do not see those problems anymore.

Signed-off-by: Dmitry Fleytman <[email protected]>
---
drivers/usb/core/config.c | 2 +-
drivers/usb/core/hub.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index 4be52c6..854c8d6 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -852,7 +852,7 @@ int usb_get_configuration(struct usb_device *dev)
}

if (dev->quirks & USB_QUIRK_DELAY_INIT)
- msleep(100);
+ msleep(200);

result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno,
bigbuffer, length);
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 822f8c5..78c2aca 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4825,7 +4825,7 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
goto loop;

if (udev->quirks & USB_QUIRK_DELAY_INIT)
- msleep(1000);
+ msleep(2000);

/* consecutive bus-powered hubs aren't reliable; they can
* violate the voltage drop budget. if the new child has
--
2.7.4

2017-09-05 20:22:31

by Guenter Roeck

Subject: Re: [PATCH] usb: Increase quirk delay for USB devices

On Tue, Sep 05, 2017 at 11:40:56AM +0300, Dmitry Fleytman wrote:
> Commit e0429362ab15
> ("usb: Add device quirk for Logitech HD Pro Webcams C920 and C930e")
> introduced quirk to workaround an issue with some Logitech webcams.
>
> The workaround is introducing delay for some USB operations.
>
> According to our testing, delay introduced by original commit
> is not long enough and in rare cases we still see issues described
> by the aforementioned commit.
>
> This patch increases delays introduced by original commit.
> Having this patch applied we do not see those problems anymore.
>
> Signed-off-by: Dmitry Fleytman <[email protected]>
> ---
> drivers/usb/core/config.c | 2 +-
> drivers/usb/core/hub.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
> index 4be52c6..854c8d6 100644
> --- a/drivers/usb/core/config.c
> +++ b/drivers/usb/core/config.c
> @@ -852,7 +852,7 @@ int usb_get_configuration(struct usb_device *dev)
> }
>
> if (dev->quirks & USB_QUIRK_DELAY_INIT)
> - msleep(100);
> + msleep(200);

How did you determine the new delays ? Was it discussed with the vendor,
or is it based on trial and error ?

Either case, did you confirm that you need to increase both delays
for the problem to disappear ?

Thanks,
Guenter

>
> result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno,
> bigbuffer, length);
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 822f8c5..78c2aca 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -4825,7 +4825,7 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
> goto loop;
>
> if (udev->quirks & USB_QUIRK_DELAY_INIT)
> - msleep(1000);
> + msleep(2000);
>
> /* consecutive bus-powered hubs aren't reliable; they can
> * violate the voltage drop budget. if the new child has
> --
> 2.7.4
>

2017-09-06 12:34:13

by Dmitry Fleytman

Subject: Re: [PATCH] usb: Increase quirk delay for USB devices

> On 5 Sep 2017, at 23:22 PM, Guenter Roeck <[email protected]> wrote:
>
> On Tue, Sep 05, 2017 at 11:40:56AM +0300, Dmitry Fleytman wrote:
>> Commit e0429362ab15
>> ("usb: Add device quirk for Logitech HD Pro Webcams C920 and C930e")
>> introduced quirk to workaround an issue with some Logitech webcams.
>>
>> The workaround is introducing delay for some USB operations.
>>
>> According to our testing, delay introduced by original commit
>> is not long enough and in rare cases we still see issues described
>> by the aforementioned commit.
>>
>> This patch increases delays introduced by original commit.
>> Having this patch applied we do not see those problems anymore.
>>
>> Signed-off-by: Dmitry Fleytman <[email protected]>
>> ---
>> drivers/usb/core/config.c | 2 +-
>> drivers/usb/core/hub.c | 2 +-
>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
>> index 4be52c6..854c8d6 100644
>> --- a/drivers/usb/core/config.c
>> +++ b/drivers/usb/core/config.c
>> @@ -852,7 +852,7 @@ int usb_get_configuration(struct usb_device *dev)
>> }
>>
>> if (dev->quirks & USB_QUIRK_DELAY_INIT)
>> - msleep(100);
>> + msleep(200);
>
> How did you determine the new delays ? Was it discussed with the vendor,
> or is it based on trial and error ?

It was based in trial and error.

>
> Either case, did you confirm that you need to increase both delays
> for the problem to disappear ?

Yes, according to testing results on our setups.

Thanks,
Dmitry

>
> Thanks,
> Guenter
>
>>
>> result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno,
>> bigbuffer, length);
>> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
>> index 822f8c5..78c2aca 100644
>> --- a/drivers/usb/core/hub.c
>> +++ b/drivers/usb/core/hub.c
>> @@ -4825,7 +4825,7 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
>> goto loop;
>>
>> if (udev->quirks & USB_QUIRK_DELAY_INIT)
>> - msleep(1000);
>> + msleep(2000);
>>
>> /* consecutive bus-powered hubs aren't reliable; they can
>> * violate the voltage drop budget. if the new child has
>> --
>> 2.7.4