[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 <sr at 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 at denx.de>
>> Cc: Bin Meng <bmeng.cn at gmail.com>
>> Cc: Marek Vasut <marex at 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 at gmail.com>
> 
> Regards,
> Bin

Thanks,
Stefan