On 17.07.20 07:33, Bin Meng wrote:
Hi Stefan,
On Thu, Jul 2, 2020 at 4:47 PM Stefan Roese sr@denx.de wrote:
These values are already swapped to CPU endianess, so swapping them
Can you please add more details as to when these values are swapped? I assume this is inside usb_select_config() which is called before this function is called?
Yes. Its swapped exactly here:
int usb_select_config(struct usb_device *dev) { unsigned char *tmpbuf = NULL; int err;
err = get_descriptor_len(dev, USB_DT_DEVICE_SIZE, USB_DT_DEVICE_SIZE); if (err) return err;
/* correct le values */ le16_to_cpus(&dev->descriptor.bcdUSB); le16_to_cpus(&dev->descriptor.idVendor); le16_to_cpus(&dev->descriptor.idProduct); le16_to_cpus(&dev->descriptor.bcdDevice);
But I wonder how this code ever worked on ARM/x86?
On ARM/x86, the little-endian swapping is a no-op. So it doesn't matter if you swap once or twice or... ;)
again is a bug. Let's remove the swap here instead.
Signed-off-by: Stefan Roese sr@denx.de Cc: Bin Meng bmeng.cn@gmail.com Cc: Marek Vasut marex@denx.de
drivers/usb/host/usb-uclass.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/host/usb-uclass.c b/drivers/usb/host/usb-uclass.c index cb79dfbbd5..aa08d4ffc6 100644 --- a/drivers/usb/host/usb-uclass.c +++ b/drivers/usb/host/usb-uclass.c @@ -416,21 +416,21 @@ static int usb_match_device(const struct usb_device_descriptor *desc, const struct usb_device_id *id) { if ((id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
id->idVendor != le16_to_cpu(desc->idVendor))
id->idVendor != desc->idVendor) return 0; if ((id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT) &&
id->idProduct != le16_to_cpu(desc->idProduct))
id->idProduct != desc->idProduct) return 0; /* No need to test id->bcdDevice_lo != 0, since 0 is never greater than any unsigned number. */ if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO) &&
(id->bcdDevice_lo > le16_to_cpu(desc->bcdDevice)))
(id->bcdDevice_lo > desc->bcdDevice)) return 0; if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI) &&
(id->bcdDevice_hi < le16_to_cpu(desc->bcdDevice)))
(id->bcdDevice_hi < desc->bcdDevice)) return 0; if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS) &&Reviewed-by: Bin Meng bmeng.cn@gmail.com
Regards, Bin
Thanks, Stefan