| Message ID | 20200322130031.10455-4-lukma@denx.de |
|---|---|
| State | New |
| Headers | show |
| Series | usb: Improve robustness of ehci-hcd controller operation | expand |
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.patch?dl=0 > > Signed-off-by: Lukasz Majewski <lukma at 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 ?
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.patch?dl=0 > > > > Signed-off-by: Lukasz Majewski <lukma at 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 -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma at denx.de -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 488 bytes Desc: OpenPGP digital signature URL: <https://lists.denx.de/pipermail/u-boot/attachments/20200323/1f4f6231/attachment.sig>
On 3/23/20 8:04 AM, Lukasz Majewski wrote: > 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.patch?dl=0 >>> >>> Signed-off-by: Lukasz Majewski <lukma at 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. I see, then please research this. The USB stack has enough ad-hoc random values in it already, no need to add new ones.
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); + if (--retry >= 0) + /* Some drives are just slow to wake up. */ + goto again; return err; } else { printf("USB device descriptor short read (expected %i, got %i)\n",
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.patch?dl=0 Signed-off-by: Lukasz Majewski <lukma at 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(-)