* [RFC PATCH] usb: core: reduce power-on-good delay time of root hub
@ 2021-04-09 2:39 Chunfeng Yun
2021-04-09 15:09 ` Alan Stern
0 siblings, 1 reply; 2+ messages in thread
From: Chunfeng Yun @ 2021-04-09 2:39 UTC (permalink / raw)
To: Greg Kroah-Hartman, Alan Stern
Cc: Matthias Brugger, Chunfeng Yun, Nishad Kamdar, linux-usb,
linux-kernel, linux-arm-kernel, linux-mediatek, Eddie Hung
Return the exactly delay time given by root hub descriptor,
this helps to reduce resume time etc.
Due to the root hub descriptor is usually provided by the host
controller driver, if there is compatibility for a root hub,
we can fix it easily without affect other root hub
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
drivers/usb/core/hub.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 73f4482d833a..22ea1f4f2d66 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -148,8 +148,10 @@ static inline unsigned hub_power_on_good_delay(struct usb_hub *hub)
{
unsigned delay = hub->descriptor->bPwrOn2PwrGood * 2;
- /* Wait at least 100 msec for power to become stable */
- return max(delay, 100U);
+ if (!hub->hdev->parent) /* root hub */
+ return delay;
+ else /* Wait at least 100 msec for power to become stable */
+ return max(delay, 100U);
}
static inline int hub_port_debounce_be_connected(struct usb_hub *hub,
--
2.18.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [RFC PATCH] usb: core: reduce power-on-good delay time of root hub
2021-04-09 2:39 [RFC PATCH] usb: core: reduce power-on-good delay time of root hub Chunfeng Yun
@ 2021-04-09 15:09 ` Alan Stern
0 siblings, 0 replies; 2+ messages in thread
From: Alan Stern @ 2021-04-09 15:09 UTC (permalink / raw)
To: Chunfeng Yun
Cc: Greg Kroah-Hartman, Matthias Brugger, Nishad Kamdar, linux-usb,
linux-kernel, linux-arm-kernel, linux-mediatek, Eddie Hung
On Fri, Apr 09, 2021 at 10:39:07AM +0800, Chunfeng Yun wrote:
> Return the exactly delay time given by root hub descriptor,
> this helps to reduce resume time etc.
>
> Due to the root hub descriptor is usually provided by the host
> controller driver, if there is compatibility for a root hub,
> we can fix it easily without affect other root hub
>
> Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
> ---
> drivers/usb/core/hub.h | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
> index 73f4482d833a..22ea1f4f2d66 100644
> --- a/drivers/usb/core/hub.h
> +++ b/drivers/usb/core/hub.h
> @@ -148,8 +148,10 @@ static inline unsigned hub_power_on_good_delay(struct usb_hub *hub)
> {
> unsigned delay = hub->descriptor->bPwrOn2PwrGood * 2;
>
> - /* Wait at least 100 msec for power to become stable */
> - return max(delay, 100U);
> + if (!hub->hdev->parent) /* root hub */
> + return delay;
> + else /* Wait at least 100 msec for power to become stable */
> + return max(delay, 100U);
> }
>
> static inline int hub_port_debounce_be_connected(struct usb_hub *hub,
> --
> 2.18.0
>
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2021-04-09 15:09 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-04-09 2:39 [RFC PATCH] usb: core: reduce power-on-good delay time of root hub Chunfeng Yun
2021-04-09 15:09 ` Alan Stern
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).