From d0d3435b212f88aebee6a06e002e4fd3b487a918 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Fri, 30 Dec 2011 08:20:50 -0300 Subject: [PATCH] [media] gspca - main: Correct use of interval in bandwidth calculation MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The calculated bandwidth should not be multiplied by the interval, but be divided by it. Also bInterbval should be interpreted as a power of 2 for isochronous endpoints. Signed-off-by: Hans de Goede Signed-off-by: Jean-François Moine Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/gspca/gspca.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c index 5b8f4fc..a82d45e 100644 --- a/drivers/media/video/gspca/gspca.c +++ b/drivers/media/video/gspca/gspca.c @@ -698,12 +698,17 @@ static int build_isoc_ep_tb(struct gspca_dev *gspca_dev, USB_ENDPOINT_XFER_ISOC); if (ep == NULL) continue; + if (ep->desc.bInterval == 0) { + pr_err("alt %d iso endp with 0 interval\n", j); + continue; + } psize = le16_to_cpu(ep->desc.wMaxPacketSize); psize = (psize & 0x07ff) * (1 + ((psize >> 11) & 3)); - bandwidth = psize * ep->desc.bInterval * 1000; + bandwidth = psize * 1000; if (gspca_dev->dev->speed == USB_SPEED_HIGH || gspca_dev->dev->speed == USB_SPEED_SUPER) bandwidth *= 8; + bandwidth /= 1 << (ep->desc.bInterval - 1); if (bandwidth <= last_bw) continue; if (bandwidth < ep_tb->bandwidth) { -- 2.7.4