From 18bef42c2d9a63e028261b88e9202b6d0d34292b Mon Sep 17 00:00:00 2001 From: =?utf8?q?Jean-Fran=C3=A7ois=20Moine?= Date: Wed, 4 Jan 2012 13:44:02 -0300 Subject: [PATCH] [media] gspca - main: Change the bandwidth estimation of isochronous transfer MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Having: - a mean image size of 0.375 time the max compressed image size and - a frame rate of 30 fps for small images or with USB 2.0/3.0 seems more realistic and gives less image freezes. Signed-off-by: Jean-François Moine Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/gspca/gspca.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c index 5ce3557bde89..cdd43ff4aa02 100644 --- a/drivers/media/video/gspca/gspca.c +++ b/drivers/media/video/gspca/gspca.c @@ -633,13 +633,14 @@ static u32 which_bandwidth(struct gspca_dev *gspca_dev) u32 bandwidth; int i; + /* get the (max) image size */ i = gspca_dev->curr_mode; bandwidth = gspca_dev->cam.cam_mode[i].sizeimage; - /* if the image is compressed, estimate the mean image size */ + /* if the image is compressed, estimate its mean size */ if (bandwidth < gspca_dev->cam.cam_mode[i].width * gspca_dev->cam.cam_mode[i].height) - bandwidth /= 3; + bandwidth = bandwidth * 3 / 8; /* 0.375 */ /* estimate the frame rate */ if (gspca_dev->sd_desc->get_streamparm) { @@ -649,7 +650,14 @@ static u32 which_bandwidth(struct gspca_dev *gspca_dev) gspca_dev->sd_desc->get_streamparm(gspca_dev, &parm); bandwidth *= parm.parm.capture.timeperframe.denominator; } else { - bandwidth *= 15; /* 15 fps */ + + /* don't hope more than 15 fps with USB 1.1 and + * image resolution >= 640x480 */ + if (gspca_dev->width >= 640 + && gspca_dev->dev->speed == USB_SPEED_FULL) + bandwidth *= 15; /* 15 fps */ + else + bandwidth *= 30; /* 30 fps */ } PDEBUG(D_STREAM, "min bandwidth: %d", bandwidth); -- 2.11.0