Hi,
yfw <nh26223@xxxxxxxxx> writes:
> Hi Felipe,
>
> On 2016/9/26 16:12, Felipe Balbi wrote:
>> According to USB Specification 2.0 table 9-4,
>> wMaxPacketSize is a bitfield. Endpoint's maxpacket
>> is laid out in bits 10:0. For high-speed,
>> high-bandwidth isochronous endpoints, bits 12:11
>> contain a multiplier to tell us how many
>> transactions we want to try per uframe.
>>
>> This means that if we want an isochronous endpoint
>> to issue 3 transfers of 1024 bytes per uframe,
>> wMaxPacketSize should contain the value:
>>
>> 1024 | (2 << 11)
>>
>> or 5120 (0x1400). In order to make Host and
>> Peripheral controller drivers' life easier, we're
>> adding a helper which returns bits 12:11. Note that
>> no care is made WRT to checking endpoint type and
>> gadget's speed. That's left for drivers to handle.
>>
>> Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
>> ---
>> include/uapi/linux/usb/ch9.h | 19 +++++++++++++++++++
>> 1 file changed, 19 insertions(+)
>>
>> diff --git a/include/uapi/linux/usb/ch9.h b/include/uapi/linux/usb/ch9.h
>> index a8acc24765fe..73bcb24d4077 100644
>> --- a/include/uapi/linux/usb/ch9.h
>> +++ b/include/uapi/linux/usb/ch9.h
>> @@ -423,6 +423,11 @@ struct usb_endpoint_descriptor {
>> #define USB_ENDPOINT_XFER_INT 3
>> #define USB_ENDPOINT_MAX_ADJUSTABLE 0x80
>>
>> +#define USB_EP_ISOC_MAXP_MULT_SHIFT 11
>> +#define USB_EP_ISOC_MAXP_MULT_MASK (3 << USB_EP_ISOC_MAXP_MULT_SHIFT)
>> +#define USB_EP_ISOC_MAXP_MULT(m) \
>> + (((m) & USB_EP_ISOC_MAXP_MULT_MASK) >> USB_EP_ISOC_MAXP_MULT_SHIFT)
>> +
>> /* The USB 3.0 spec redefines bits 5:4 of bmAttributes as interrupt ep type. */
>> #define USB_ENDPOINT_INTRTYPE 0x30
>> #define USB_ENDPOINT_INTR_PERIODIC (0 << 4)
>> @@ -630,6 +635,20 @@ static inline int usb_endpoint_maxp(const struct usb_endpoint_descriptor *epd)
>> return __le16_to_cpu(epd->wMaxPacketSize);
>> }
>>
>> +/**
>> + * usb_endpoint_isoc_maxp_mult - get endpoint's transactional opportunities
>> + * @epd: endpoint to be checked
>> + *
>> + * Return @epd's wMaxPacketSize[12:11] + 1
>> + */
>> +static inline int
>> +usb_endpoint_isoc_maxp_mult(const struct usb_endpoint_descriptor *epd)
>> +{
>> + int maxp = __le16_to_cpu(epd->wMaxPacketSize);
>> +
>> + return USB_EP_ISOC_MAXP_MULT(maxp) + 1;
>> +}
>> +
>> static inline int usb_endpoint_interrupt_type(
>> const struct usb_endpoint_descriptor *epd)
>> {
>>
> Does this mean the issue of isoc high bandwidth transfer was fixed by
> this patchset per your test?
No, I couldn't get g_webcam to work yet.
--
balbi
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