Hi Marek,
On 3/22/20 2:00 PM, Lukasz Majewski wrote:
This change provides some extra time for some slow (or degraded) USB devices to become fully operational.
This code is the port to newest U-Boot of the fix from - "rayvt" (from [1]).
Links: [1] - https://forum.doozan.com/read.php?3,35295,35295#msg-35295 [2] - https://www.dropbox.com/s/nrkrd1no63viuu8/uboot-bodhi-2016.05-timeoutTD.patc...
Signed-off-by: Lukasz Majewski lukma@denx.de [Unfortunately, the original patch [2] did not contain S-o-B from the original author - "rayvt"]
common/usb.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/common/usb.c b/common/usb.c index 349e838f1d..305482b5bb 100644 --- a/common/usb.c +++ b/common/usb.c @@ -925,14 +925,20 @@ static int get_descriptor_len(struct usb_device *dev, int len, int expect_len) __maybe_unused struct usb_device_descriptor *desc; ALLOC_CACHE_ALIGN_BUFFER(unsigned char, tmpbuf, USB_BUFSIZ); int err;
int retry = 5;
desc = (struct usb_device_descriptor *)tmpbuf;
+again: err = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, len); if (err < expect_len) { if (err < 0) {
printf("unable to get device descriptor(error=%d)\n",
err);
printf("unable to get device descriptor(error=%d) retry: %d\n",
err, retry);mdelay(50);Why 50 mSec and not some other value, like 100 mSec ?
I think that this value (50 ms) was took from Linux in some point and with the retry set to 5 was the ported heuristics.
If you ask why exactly there is 50 ms - I cannot say, as I've just ported the patch.
Best regards,
Lukasz Majewski
--
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