On 9/8/25 3:41 PM, Ravulapalli, Naresh Kumar wrote:
On 08-Sep-25 6:32 PM, Marek Vasut wrote:
On 9/8/25 10:44 AM, Ravulapalli, Naresh Kumar wrote:
Hi Marek
On 02-Sep-25 11:48 PM, Marek Vasut wrote:
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On 9/2/25 9:52 AM, Ravulapalli, Naresh Kumar wrote:
On 30-Aug-25 5:30 AM, Marek Vasut wrote:
On 8/29/25 6:19 PM, Ravulapalli, Naresh Kumar wrote:
Hi Marek
On 29-Aug-25 2:11 PM, Marek Vasut wrote:
On 8/8/25 12:04 PM, Naresh Kumar Ravulapalli wrote:
Some USB devices need more time to be initialized. Hence,
increasing the default USB Hub debounce timeout value for
devices to be discovered, connected to Agilex5 boards.
Is this really hub debounce timeout or usb_pgood_delay ?
Which devices are those, include that in the commit message.
Yes, timeout is related to USB connect/disconnect signal bounces not
about bus stability during init.
Issue was mainly observed with legacy flash drives. Maybe I will
change
commit text from "Some USB devices need more time to be
initialized..."
to "Some old USB flash drives need more time to be initialized
during
connect or disconnect events ..."?
Note that I am not modifying the default Kconfig value in general;
change is only made for an SoCFPGA devkit we tested.
Does this same issue go away if you set usb_pgood_delay to 2000 or
higher too ?
No, changing USB HUB debounce timeout is working for us.
Look at this code:
https://source.denx.de/u-boot/u-boot/-/blob/master/common/usb_hub.c?
ref_type=heads#L199
"
#if CONFIG_IS_ENABLED(ENV_SUPPORT)
env = env_get("usb_pgood_delay");
if (env)
pgood_delay = max(pgood_delay,
(unsigned)simple_strtol(env, NULL,
0));
#endif
debug("pgood_delay=%dms\n", pgood_delay);
/*
* Do a minimum delay of the larger value of 100ms or
pgood_delay
* so that the power can stablize before the devices are
queried
*/
hub->query_delay = get_timer(0) + max(100, (int)pgood_delay);
/*
* Record the power-on timeout here. The max. delay (timeout)
* will be done based on this value in the USB port loop in
* usb_hub_configure() later.
*/
hub->connect_timeout = hub->query_delay + HUB_DEBOUNCE_TIMEOUT;
debug("devnum=%d poweron: query_delay=%d connect_timeout=%d\n",
dev->devnum, max(100, (int)pgood_delay),
max(100, (int)pgood_delay) + HUB_DEBOUNCE_TIMEOUT);
"
Changing both usb_pgood_delay or (CONFIG_USB_)HUB_DEBOUNCE_TIMEOUT
should have the same effect. How come it does not ?
CONFIG_USB_HUB_DEBOUNCE_TIMEOUT and pgood_delay are used for different
purposes. If I am not mistaken I think I explained this in my earlier
comments.
Anyway, to further elaborate, CONFIG_USB_HUB_DEBOUNCE_TIMEOUT is used
for debounce timeouts during device connect events and pgood_delay is
used during initial VBus stabilization.
You would be able to see this difference in the link below, where
pgood_delay which is populated into "hub->query_delay" is used for
voltages to stabilize before initiating communication and "hub-
>connect_timeout" where "HUB_DEBOUNCE_TIMEOUT" is populated is used
after getting the port status.
https://github.com/u-boot/u-boot/
blob/328747974a0620d0996113fe2b3906b06e96de00/common/usb_hub.c#L455
Also, the change made as part of the comment is not applicable to the
USB stack in general; it is only for our devkit defconfig.
But none of this answers my question, looking at the aforementioned code
-- Changing both usb_pgood_delay or (CONFIG_USB_)HUB_DEBOUNCE_TIMEOUT
should have the same effect. How come it does not in your case ?
Maybe I wasn't explicit in my earlier comment, "No, changing USB HUB
debounce timeout is working for us."
USB_HUB_DEBOUNCE_TIMEOUT is basically the hard-coded-into-U-Boot-binary
version of "usb_pgood_delay" . The upside of "usb_pgood_delay" is that
users can change the value at runtime, which helps in case users need to
use some broken USB storage device which takes more than
"usb_pgood_delay" ms to start up. You cannot do that with
USB_HUB_DEBOUNCE_TIMEOUT .
Since the commit description talks about "Some USB devices need more
time to be initialized." , this looks more like "usb_pgood_delay" type
of issue.
What I meant is I didn't want to modify usb_pgood_delay as my issue was
with HUB_DEBOUNCE_TIMEOUT, so modifying this value worked for us.
Does it also work if you modify usb_pgood_delay instead ?
