> On Fri, Dec 30, 2011 at 3:54 PM, Dave Jones <davej@xxxxxxxxxx> wrote: > > We're getting a bunch of reports against Fedora 16 > > (still using 3.1) which look like some drivers are trying to > > load firmware on resume from suspend, while usermodehelper > > is disabled. > > Ok, buggy drivers. You *must*not* load firmware in your resume path, > since there is no actual guarantee that any particular device will be > resumed after the disk that contains the firmware images. > > So it's very simple: drivers that load firmware at resume time are > buggy. No ifs, buts, or maybes about it. > > > Here are some example traces: > > > > https://bugzilla.redhat.com/show_bug.cgi?id=746411 > > It's isight_firmware_load(), in the isight_firmware driver. The driver > doesn't actually do anything but load the firmware, and is apparently > not very good at that either. > > It should either fake a disconnect and reconnect of the device (and > let the reconnect then load the firmware through udev or something) or > it should just save the firmware image in memory from the original > load, and make the resume just re-initialize it - not load it. Hey, maybe we should implement such thing into the firmware loader itself? Allow it -- for example via some node in /dev -- to force loading firmware into some buffer in kernel just before suspend so it'll certainly be readily available at resume time? M > > It's also possible that it could be considered a USB layer bug, and > the USB layer should just not rebind the devices directly in the > resume function, but do it somehow later. HOWEVER, that would only > work for "random" USB devices that aren't in use by user space (like > disks etc might be). So I think that in general the real solution is > always just "make sure that the firmware is in memory before the > suspend even happens". > > Greg - has the USB resume logic been changed lately? > > Matthew? Any comments about that particular driver? > > > https://bugzilla.redhat.com/show_bug.cgi?id=771002 > > Same issue, different driver. Again, it's USB, and it's possible that > USB just makes it really hard to do this correctly (ie the "save > firmware image across suspend so that you don't have to load it at > resume time"). > > It's also possible that we should blame the firmware code, which is > expressly written to encourage these kinds of bugs. It may be that i > tshould be the firmware code that has a "get_firmware()" + > "put_firmware()" model, and it should cache the firmware explicitly if > the config supports suspend, so that a firmware read at resume time > would actually work. The whole "request_firmware()" interface really > is very prone to these kinds of bugs. > > But it's possible this could be fixed at the driver level by doing the > caching there. > > In this case it's the rtl8192cu driver, so Larry, Chaoming, John etc > added to the cc for that one. > > > This possibly sounds like the problem that > > caca9510ff4e5d842c0589110243d60927836222 was trying to fix, but that > > patch is present in the kernels > > being reported. > > No, caca9510ff4e is only for the case where you actually compile the > firmware *into* the kernel, so it's part of the kernel image. That's > useful mainly for avoiding modules and initrd images, thus allowing > things like having root directly on a disk that needs firmware to be > loaded. Quite unusual, and it doesn't really work all that well. > > Oh, and some people use it for the Radeon firmware with the radeon DRM > code built it. > > It really does need to be fixed at a driver level (possibly with the > help of firmware/usb support infrastructure). > > Linus > -- > 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
