From 3687e1e67e4920a202d53cc24678fb34fcda8fc5 Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Fri, 8 Feb 2008 15:44:25 -0300 Subject: V4L/DVB (7179): Allow more than one em28xx board em28xx driver is capable of handling more than one usb device. However, isoc transfers require a large amount of data to be transfered. Before this patch, just one em28xx board were enough to allocate more than 50% URBs: T: Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 8 B: Alloc=480/800 us (60%), #Int= 0, #Iso= 2 D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=01 MxPS=64 #Cfgs= 1 So, only one board could use an USB host at the same time. After the patch, it is possible to use more than one em28xx at the same time, on the same usb host, if the image size is slower or equal to 345600, since those images will require about 30% of the URBs: T: Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 8 B: Alloc=232/800 us (29%), #Int= 0, #Iso= 2 D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=01 MxPS=64 #Cfgs= 1 So, in thesis, after the patch, it would be possible to use up to 3 boards by each usb host, if the devices are generating small images. Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/em28xx/em28xx.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/media/video/em28xx/em28xx.h') diff --git a/drivers/media/video/em28xx/em28xx.h b/drivers/media/video/em28xx/em28xx.h index 813c0af458d3..04e0e48ecabe 100644 --- a/drivers/media/video/em28xx/em28xx.h +++ b/drivers/media/video/em28xx/em28xx.h @@ -33,7 +33,7 @@ #define UNSET -1 /* maximum number of em28xx boards */ -#define EM28XX_MAXBOARDS 1 /*FIXME: should be bigger */ +#define EM28XX_MAXBOARDS 4 /*FIXME: should be bigger */ /* maximum number of frames that can be queued */ #define EM28XX_NUM_FRAMES 5 -- cgit v1.2.2