Re: [U-Boot] [PATCH v3 3/3] usb: Early failure when the first descriptor read fails or is invalid
Le mardi 07 avril 2015 à 23:41 -0600, Stephen Warren a écrit : > On 04/07/2015 11:07 PM, Stephen Warren wrote: > > On 04/04/2015 07:12 AM, Paul Kocialkowski wrote: > >> This may happen when using an USB1 device on a controller that only > >> supports > >> USB2 (e.g. EHCI). Reading the first descriptor will fail (read 0 byte), so > >> we > >> can abort the process at this point instead of failing later and wasting > >> time. > > > > FYI, this patch breaks USB keyboard (or perhaps any USB 1.x device) > > support on the RPi. Damn, I'm really sorry about that, I wish I had had more hardware available to test it thoroughly and that I had thought twice about it and foresaw that issue. My sincerest apologies for that mistake and of course, thanks for noticing and picking it up! > >> diff --git a/common/usb.c b/common/usb.c > > > >> @@ -956,7 +956,7 @@ int usb_new_device(struct usb_device *dev) > >> */ > >> #ifndef CONFIG_USB_XHCI > >>err = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, 64); > >> - if (err < 0) { > >> + if (err < sizeof(struct usb_device_descriptor)) { > >>debug("usb_new_device: usb_get_descriptor() failed\n"); > >>return -EIO; > >>} > > > > The value returned here is 8 not 18 (the sizeof the descriptor), so the > > code bails out with an error. That makes sense on USB low speed devices. > > Given the description of what this patch is attempting to achieve, > > shouldn't the replacement check be: > > > > if (err <= 0) { > > > > My guess for why the value 8 is returned is because the device's > > maxpacket is 8, and the DWC2 driver only attempts to transfer 1 packet > > because the requested transfer size is 64, and the default packet size > > is 64, which means 1 packet. Note that DWC2 HW (perhaps unlike e.g. > > EHCI) requires the driver to specify the number of packets transferred, > > not a byte count. However, I haven't validated that yet. My device is a > > USB 1.x FS keyboard. > > Yes, I can avoid the error by hacking dwc2.c's assignment of max: > > > int chunk_msg(struct usb_device *dev, unsigned long pipe, int *pid, int in, > > void *buffer, int len, bool ignore_ack) > > { > ... > > int max = usb_maxpacket(dev, pipe); > > and forcing that to 8 rather than 64 for the data transfer phase of the > first transaction to each USB device (my keyboard has a built-in hub, so > I need to override a few different transactions). > > Thinking about the fix more, perhaps something like the following is > appropriate: > > if (err < offsetof(struct usb_device_descriptor, idVendor)) I would be happy with using 8 directly since that's AFAIK the smallest packet size that should be used on USB. Using offsetof, while not requiring any hardcoded value, seems a bit unclean to me as it abstracts that fact. > ... since idVendor is the first field that's not used by the code that > processes the results of the initial descriptor read. Hopefully there > are no devices with a control endpoint bMaxPacketSize0 less than 8 > (which is what that offsetof evaluates to). > http://www.usbmadesimple.co.uk/ums_3.htm seems to imply that's the case, > saying for control transfers: That makes sense, too. > The max packet size for the data stage is 8 bytes at low speed, 8, 16, > 32 or 64 at full Speed and 64 for high speed. > > (although one of my keyboards has a maxPacket of 4 for EP 2, but I > thinkt hat's something different) > > Also note the comment a little before the code this patch affects in > U-Boot's common/usb.c: > > > /* send 64-byte GET-DEVICE-DESCRIPTOR request. Since the descriptor is > > * only 18 bytes long, this will terminate with a short packet. But if > > * the maxpacket size is 8 or 16 the device may be waiting to transmit > > * some more, or keeps on retransmitting the 8 byte header. */ signature.asc Description: This is a digitally signed message part ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
Re: [U-Boot] [PATCH v3 3/3] usb: Early failure when the first descriptor read fails or is invalid
On 04/07/2015 11:07 PM, Stephen Warren wrote: > On 04/04/2015 07:12 AM, Paul Kocialkowski wrote: >> This may happen when using an USB1 device on a controller that only supports >> USB2 (e.g. EHCI). Reading the first descriptor will fail (read 0 byte), so we >> can abort the process at this point instead of failing later and wasting >> time. > > FYI, this patch breaks USB keyboard (or perhaps any USB 1.x device) > support on the RPi. > >> diff --git a/common/usb.c b/common/usb.c > >> @@ -956,7 +956,7 @@ int usb_new_device(struct usb_device *dev) >> */ >> #ifndef CONFIG_USB_XHCI >> err = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, 64); >> -if (err < 0) { >> +if (err < sizeof(struct usb_device_descriptor)) { >> debug("usb_new_device: usb_get_descriptor() failed\n"); >> return -EIO; >> } > > The value returned here is 8 not 18 (the sizeof the descriptor), so the > code bails out with an error. > > Given the description of what this patch is attempting to achieve, > shouldn't the replacement check be: > > if (err <= 0) { > > My guess for why the value 8 is returned is because the device's > maxpacket is 8, and the DWC2 driver only attempts to transfer 1 packet > because the requested transfer size is 64, and the default packet size > is 64, which means 1 packet. Note that DWC2 HW (perhaps unlike e.g. > EHCI) requires the driver to specify the number of packets transferred, > not a byte count. However, I haven't validated that yet. My device is a > USB 1.x FS keyboard. Yes, I can avoid the error by hacking dwc2.c's assignment of max: > int chunk_msg(struct usb_device *dev, unsigned long pipe, int *pid, int in, > void *buffer, int len, bool ignore_ack) > { ... > int max = usb_maxpacket(dev, pipe); and forcing that to 8 rather than 64 for the data transfer phase of the first transaction to each USB device (my keyboard has a built-in hub, so I need to override a few different transactions). Thinking about the fix more, perhaps something like the following is appropriate: if (err < offsetof(struct usb_device_descriptor, idVendor)) ... since idVendor is the first field that's not used by the code that processes the results of the initial descriptor read. Hopefully there are no devices with a control endpoint bMaxPacketSize0 less than 8 (which is what that offsetof evaluates to). http://www.usbmadesimple.co.uk/ums_3.htm seems to imply that's the case, saying for control transfers: The max packet size for the data stage is 8 bytes at low speed, 8, 16, 32 or 64 at full Speed and 64 for high speed. (although one of my keyboards has a maxPacket of 4 for EP 2, but I thinkt hat's something different) Also note the comment a little before the code this patch affects in U-Boot's common/usb.c: > /* send 64-byte GET-DEVICE-DESCRIPTOR request. Since the descriptor is >* only 18 bytes long, this will terminate with a short packet. But if >* the maxpacket size is 8 or 16 the device may be waiting to transmit >* some more, or keeps on retransmitting the 8 byte header. */ ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
Re: [U-Boot] [PATCH v3 3/3] usb: Early failure when the first descriptor read fails or is invalid
On 04/04/2015 07:12 AM, Paul Kocialkowski wrote: > This may happen when using an USB1 device on a controller that only supports > USB2 (e.g. EHCI). Reading the first descriptor will fail (read 0 byte), so we > can abort the process at this point instead of failing later and wasting time. FYI, this patch breaks USB keyboard (or perhaps any USB 1.x device) support on the RPi. > diff --git a/common/usb.c b/common/usb.c > @@ -956,7 +956,7 @@ int usb_new_device(struct usb_device *dev) >*/ > #ifndef CONFIG_USB_XHCI > err = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, 64); > - if (err < 0) { > + if (err < sizeof(struct usb_device_descriptor)) { > debug("usb_new_device: usb_get_descriptor() failed\n"); > return -EIO; > } The value returned here is 8 not 18 (the sizeof the descriptor), so the code bails out with an error. Given the description of what this patch is attempting to achieve, shouldn't the replacement check be: if (err <= 0) { My guess for why the value 8 is returned is because the device's maxpacket is 8, and the DWC2 driver only attempts to transfer 1 packet because the requested transfer size is 64, and the default packet size is 64, which means 1 packet. Note that DWC2 HW (perhaps unlike e.g. EHCI) requires the driver to specify the number of packets transferred, not a byte count. However, I haven't validated that yet. My device is a USB 1.x FS keyboard. ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
[U-Boot] [PATCH v3 3/3] usb: Early failure when the first descriptor read fails or is invalid
This may happen when using an USB1 device on a controller that only supports USB2 (e.g. EHCI). Reading the first descriptor will fail (read 0 byte), so we can abort the process at this point instead of failing later and wasting time. Signed-off-by: Paul Kocialkowski --- common/usb.c | 5 - 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/common/usb.c b/common/usb.c index 6ed3124..f648847 100644 --- a/common/usb.c +++ b/common/usb.c @@ -956,7 +956,7 @@ int usb_new_device(struct usb_device *dev) */ #ifndef CONFIG_USB_XHCI err = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, 64); - if (err < 0) { + if (err < sizeof(struct usb_device_descriptor)) { debug("usb_new_device: usb_get_descriptor() failed\n"); return -EIO; } @@ -996,6 +996,9 @@ int usb_new_device(struct usb_device *dev) case 64: dev->maxpacketsize = PACKET_SIZE_64; break; + default: + printf("usb_new_device: invalid max packet size\n"); + return -EIO; } dev->devnum = addr; -- 1.9.1 ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot