From: Hans de Goede <hdegoede@redhat.com>
Date: Fri, 30 Dec 2011 11:20:50 +0000 (-0300)
Subject: [media] gspca - main: Correct use of interval in bandwidth calculation
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=d0d3435b212f88aebee6a06e002e4fd3b487a918;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git
[media] gspca - main: Correct use of interval in bandwidth calculation
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 <hdegoede@redhat.com>
Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
---
diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c
index 5b8f4fc5d1c6..a82d45e57896 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) {