Re: [PATCH v1 3/4] usb: usb-uclass.c: Drop le16_to_cpu() as values are already swapped

[Stefan Roese]

On 17.07.20 07:33, Bin Meng wrote:

Hi Stefan,

On Thu, Jul 2, 2020 at 4:47 PM Stefan Roese <s...@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 <s...@denx.de>
Cc: Bin Meng <bmeng...@gmail.com>
Cc: Marek Vasut <ma...@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...@gmail.com>

Regards,
Bin

Thanks,
Stefan