Hi Ruslan, Thanks for the tips! A few comments below: On Friday 10 May 2013 13.54.53 Ruslan Bilovol wrote: > Hello Frederic, > > On Fri, May 10, 2013 at 12:54 PM, Frederik Schmid > > <frederik.schmid@xxxxxxxxx> wrote: > > Well, my conclusion is that this setup, IDS-camera + musb, is horribly > > sensitive to interrupt latency. > > > > If the musb-interrupt is blocked for ~100us the pipe is stalled. Most of > > the interrupts on my target were routed to CPU0 while CPU1 had few. > > > > When I re-route the musb interrupts to CPU1 throughput increases to > > ~120Mbps but I've only reduced the probability of the interrupt being > > blocked. > If you want to increase throughput over musb on omap4, usually next steps > help: - route musb IRQ to another CPU if possible Done that. > - check if musb uses DMA mode (not PIO) It does. > - check if the data (urb) passed to musb is aligned, if not - apply next > patch: > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id= > 8408fd1d83e39bf856d31a36b70bcc53527702fd - play with double packet buffering Didn't check but I applied your patch anyway. Doesn't seem to make any difference. > - increase OPP - this will reduce latency I'm not sure what this means. Something to do with power management? Is there something specific I could try? > > But I can say that on OMAP4 throughput over musb will be lower than > over ehci controller because > ehci one does many things in HW whereas musb have to do some of them in SW. > My scores for musb were ~145 Mbits/s for bulk transfers, but they > probably may be increased after additional tuning. > > > The only hope this application has is if MODE1 in the controller could > > alleviate latency dependence but MODE1 seems quite broken in the hardware? > > > > musb_host.c: > > > > /* Disadvantage of using mode 1: > > * It's basically usable only for mass storage class; essentially all > > * other protocols also terminate transfers on short packets. > > * ... > > */ > > > > Best regards, > > Frederik > > > > On Friday 10 May 2013 07.26.35 Frederik Schmid wrote: > >> Hi Greg, > >> > >> The kernel is based on 3.4.11 from omapzoom.org (ti-ubuntu-3.4-1487) with > >> Variscite BSP patches from: > >> > >> http://www.variwiki.com/index.php?title=VAR-SOM-OM44_-_Ubuntu_Precise > >> > >> I was expecting 200-250Mbps which is entirly possible on the same chip > >> using its ehci-controller. musb seems to sustain this speed also, for > >> most of the time, until a "glitch" like the one in the screenshot stalls > >> the pipe. > >> > >> We don't want to use the ehci-controller because it's already bogged down > >> with an ethernet controller. > >> > >> Regards, > >> Frederik > >> > >> On Thursday 09 May 2013 08.12.47 Greg KH wrote: > >> > On Thu, May 09, 2013 at 10:44:05AM +0200, Frederik Schmid wrote: > >> > > Hi, > >> > > > >> > > I'm developing a camera application on a TI OMAP4460. I have a cmos > >> > > usb-camera from IDS (UI-1551-LE-C-HQ) connected to the OTG-port (musb > >> > > as > >> > > host) on the OMAP. > >> > > > >> > > I get very poor frame rates with this setup reliably. The throughput > >> > > rate > >> > > is ~50-70Mbps. (1600x1200,8bpp,3-5fps) > >> > > > >> > > I uploaded a screenshot of a packet trace here: > >> > > > >> > > http://i.imgur.com/26XL23T.png > >> > > > >> > > The host seems to keep up with the camera most of the time but > >> > > occasionally > >> > > some kind of "glitch" causes the host to lag behind and the camera > >> > > signals > >> > > STALL because of buffer overrun. > >> > > >> > What kernel version are you using? And what data rate do you expect to > >> > be getting with this hardware configuration? > >> > > >> > thanks, > >> > > >> > greg k-h > >> > >> -- > >> To unsubscribe from this list: send the line "unsubscribe linux-usb" in > >> the body of a message to majordomo@xxxxxxxxxxxxxxx > >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-usb" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
