Hi,
Bin Liu <b-liu@xxxxxx> writes:
> Hi,
>
> I am trying to check Isoch high bandwidth transfer with g_webcam.ko in
> high-speed connection.
>
> First I hacked webcam.c as follows to enable 640x480@30fps mode.
>
> diff --git a/drivers/usb/gadget/legacy/webcam.c b/drivers/usb/gadget/legacy/webcam.c
> index 72c976b..9eb315f 100644
> --- a/drivers/usb/gadget/legacy/webcam.c
> +++ b/drivers/usb/gadget/legacy/webcam.c
> @@ -191,15 +191,15 @@ static const struct UVC_FRAME_UNCOMPRESSED(3) uvc_frame_yuv_360p = {
> .bFrameIndex = 1,
> .bmCapabilities = 0,
> .wWidth = cpu_to_le16(640),
> - .wHeight = cpu_to_le16(360),
> + .wHeight = cpu_to_le16(480),
> .dwMinBitRate = cpu_to_le32(18432000),
> .dwMaxBitRate = cpu_to_le32(55296000),
> - .dwMaxVideoFrameBufferSize = cpu_to_le32(460800),
> - .dwDefaultFrameInterval = cpu_to_le32(666666),
> + .dwMaxVideoFrameBufferSize = cpu_to_le32(614400),
> + .dwDefaultFrameInterval = cpu_to_le32(333333),
> .bFrameIntervalType = 3,
> - .dwFrameInterval[0] = cpu_to_le32(666666),
> - .dwFrameInterval[1] = cpu_to_le32(1000000),
> - .dwFrameInterval[2] = cpu_to_le32(5000000),
> + .dwFrameInterval[0] = cpu_to_le32(333333),
> + .dwFrameInterval[1] = cpu_to_le32(666666),
> + .dwFrameInterval[2] = cpu_to_le32(1000000),
> };
>
> then loaded g_webcam.ko as
>
> # modprobe g_webcam streaming_maxpacket=3072
>
> The endpoint descriptor showing on the host is
>
> Endpoint Descriptor:
> bLength 7
> bDescriptorType 5
> bEndpointAddress 0x8d EP 13 IN
> bmAttributes 5
> Transfer Type Isochronous
> Synch Type Asynchronous
> Usage Type Data
> wMaxPacketSize 0x1400 3x 1024 bytes
> bInterval 1
>
> However the usb bus trace shows only one transaction with 1024-bytes packet in
> every SOF. The host only sends one IN packet in every SOF, I am expecting 2~3
> 1024-bytes transactions, since this would be required to transfer 640x480@30fps
> YUV frames in high-speed.
>
> DId I miss anything in the setup?
MUSB or DWC3? This looks like a UDC bug to me. Can you show a screenshot
of your bus analyzer? When host sends IN token, are you replying with
DATA0, DATA1 or DATA2?
--
balbi
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