diff mbox series

xhci: Check all endpoints for LPM timeout

Message ID 20190912144921.368-1-jan@centricular.com (mailing list archive)
State Mainlined
Commit d500c63f80f2ea08ee300e57da5f2af1c13875f5
Headers show
Series xhci: Check all endpoints for LPM timeout | expand

Commit Message

Jan Schmidt Sept. 12, 2019, 2:49 p.m. UTC 
If an endpoint is encountered that returns USB3_LPM_DEVICE_INITIATED, keep
checking further endpoints, as there might be periodic endpoints later
that return USB3_LPM_DISABLED due to shorter service intervals.

Without this, the code can set too high a maximum-exit-latency and
prevent the use of multiple USB3 cameras that should be able to work.

Signed-off-by: Jan Schmidt <jan@centricular.com>
Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 drivers/usb/host/xhci.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Philipp Zabel Sept. 12, 2019, 3:14 p.m. UTC | #1 
On Fri, 2019-09-13 at 00:49 +1000, Jan Schmidt wrote:
> If an endpoint is encountered that returns USB3_LPM_DEVICE_INITIATED, keep
> checking further endpoints, as there might be periodic endpoints later
> that return USB3_LPM_DISABLED due to shorter service intervals.
> 
> Without this, the code can set too high a maximum-exit-latency and
> prevent the use of multiple USB3 cameras that should be able to work.
> 
> Signed-off-by: Jan Schmidt <jan@centricular.com>
> Tested-by: Philipp Zabel <p.zabel@pengutronix.de>

This fixes the capture from multiple Oculus Sensors, as described in the
"Not enough bandwidth with Magewell XI100DUSB-HDMI" thread:

https://lore.kernel.org/linux-usb/CA+gwMce-h9LPCv1hhfEcRz_2w9mEQLOjy42dcjvPxTeawSU5kQ@mail.gmail.com/

regards
Philipp
Mathias Nyman Sept. 13, 2019, 12:58 p.m. UTC | #2 
On 12.9.2019 17.49, Jan Schmidt wrote:
> If an endpoint is encountered that returns USB3_LPM_DEVICE_INITIATED, keep
> checking further endpoints, as there might be periodic endpoints later
> that return USB3_LPM_DISABLED due to shorter service intervals.
> 
> Without this, the code can set too high a maximum-exit-latency and
> prevent the use of multiple USB3 cameras that should be able to work.
> 
> Signed-off-by: Jan Schmidt <jan@centricular.com>
> Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
> ---
>   drivers/usb/host/xhci.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 03d1e552769b..1986b88661fc 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -4673,12 +4673,12 @@ static int xhci_update_timeout_for_endpoint(struct xhci_hcd *xhci,
>   	alt_timeout = xhci_call_host_update_timeout_for_endpoint(xhci, udev,
>   		desc, state, timeout);
>   
> -	/* If we found we can't enable hub-initiated LPM, or
> +	/* If we found we can't enable hub-initiated LPM, and
>   	 * the U1 or U2 exit latency was too high to allow
> -	 * device-initiated LPM as well, just stop searching.
> +	 * device-initiated LPM as well, then we will disable LPM
> +	 * for this device, so stop searching any further.
>   	 */
> -	if (alt_timeout == USB3_LPM_DISABLED ||
> -			alt_timeout == USB3_LPM_DEVICE_INITIATED) {
> +	if (alt_timeout == USB3_LPM_DISABLED) {
>   		*timeout = alt_timeout;
>   		return -E2BIG;
>   	}
> 

Thanks, nice catch. Adding to queue.

While looking at this I see we have a similar issue if driver has
"disable_hub_initiated_lpm" flag set.

xhci_get_timeout_no_hub_lpm() might return USB3_LPM_DEVICE_INITIATED
before we check if periodic endpoints would require disabling LPM
completely.

xhci_calculate_lpm_timeout()
...
     for (i = 0; i < config->desc.bNumInterfaces; i++) {
         ...
         if (intf->dev.driver) {
             ...
             if (driver && driver->disable_hub_initiated_lpm) {
                 return xhci_get_timeout_no_hub_lpm(udev, state);

I'll write a patch for that

-Mathias
Jan Schmidt Sept. 13, 2019, 1:46 p.m. UTC | #3 
On 13/9/19 10:58 pm, Mathias Nyman wrote:
> On 12.9.2019 17.49, Jan Schmidt wrote:
>> If an endpoint is encountered that returns USB3_LPM_DEVICE_INITIATED,
>> keep
>> checking further endpoints, as there might be periodic endpoints later
>> that return USB3_LPM_DISABLED due to shorter service intervals.
>>
>> Without this, the code can set too high a maximum-exit-latency and
>> prevent the use of multiple USB3 cameras that should be able to work.
>>
>> Signed-off-by: Jan Schmidt <jan@centricular.com>
>> Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
>> ---
>>   drivers/usb/host/xhci.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
>> index 03d1e552769b..1986b88661fc 100644
>> --- a/drivers/usb/host/xhci.c
>> +++ b/drivers/usb/host/xhci.c
>> @@ -4673,12 +4673,12 @@ static int
>> xhci_update_timeout_for_endpoint(struct xhci_hcd *xhci,
>>       alt_timeout = xhci_call_host_update_timeout_for_endpoint(xhci,
>> udev,
>>           desc, state, timeout);
>>   -    /* If we found we can't enable hub-initiated LPM, or
>> +    /* If we found we can't enable hub-initiated LPM, and
>>        * the U1 or U2 exit latency was too high to allow
>> -     * device-initiated LPM as well, just stop searching.
>> +     * device-initiated LPM as well, then we will disable LPM
>> +     * for this device, so stop searching any further.
>>        */
>> -    if (alt_timeout == USB3_LPM_DISABLED ||
>> -            alt_timeout == USB3_LPM_DEVICE_INITIATED) {
>> +    if (alt_timeout == USB3_LPM_DISABLED) {
>>           *timeout = alt_timeout;
>>           return -E2BIG;
>>       }
>>
> 
> Thanks, nice catch. Adding to queue.

Great news for the Oculus Rift support we're working on :)

> While looking at this I see we have a similar issue if driver has
> "disable_hub_initiated_lpm" flag set.
> 
> xhci_get_timeout_no_hub_lpm() might return USB3_LPM_DEVICE_INITIATED
> before we check if periodic endpoints would require disabling LPM
> completely.

Indeed - sorry, I didn't even think to look past the immediate issue.

> xhci_calculate_lpm_timeout()
> ...
>     for (i = 0; i < config->desc.bNumInterfaces; i++) {
>         ...
>         if (intf->dev.driver) {
>             ...
>             if (driver && driver->disable_hub_initiated_lpm) {
>                 return xhci_get_timeout_no_hub_lpm(udev, state);
> 
> I'll write a patch for that

I'll be happy to test by hard-coding the flag.

- Jan.

> 
> -Mathias
diff mbox series

Patch

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 03d1e552769b..1986b88661fc 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4673,12 +4673,12 @@  static int xhci_update_timeout_for_endpoint(struct xhci_hcd *xhci,
 	alt_timeout = xhci_call_host_update_timeout_for_endpoint(xhci, udev,
 		desc, state, timeout);
 
-	/* If we found we can't enable hub-initiated LPM, or
+	/* If we found we can't enable hub-initiated LPM, and
 	 * the U1 or U2 exit latency was too high to allow
-	 * device-initiated LPM as well, just stop searching.
+	 * device-initiated LPM as well, then we will disable LPM
+	 * for this device, so stop searching any further.
 	 */
-	if (alt_timeout == USB3_LPM_DISABLED ||
-			alt_timeout == USB3_LPM_DEVICE_INITIATED) {
+	if (alt_timeout == USB3_LPM_DISABLED) {
 		*timeout = alt_timeout;
 		return -E2BIG;
 	}