On Fri, Nov 15, 2019 at 11:21:53AM +0800, Greg Kroah-Hartman wrote: > On Thu, Nov 14, 2019 at 08:02:34AM -0600, Bin Liu wrote: > > On Thu, Nov 14, 2019 at 11:20:18AM +0800, Greg Kroah-Hartman wrote: > > > On Tue, Nov 12, 2019 at 09:28:57AM -0600, Bin Liu wrote: > > > > Hi, > > > > > > > > On Tue, Nov 12, 2019 at 02:51:51PM +0800, Chunfeng Yun wrote: > > > > > Now the USB gadget subsystem can use the USB debugfs root directory, > > > > > so move musb's directory from the root of the debugfs filesystem into > > > > > the root of usb > > > > > > > > My opinion is this move is unnecessary. I breaks existing debug tools or > > > > documentation which is already published on Internet. > > > > > > Having a "root" directory for a single random driver seems like you are > > > making your driver a "very important" thing in the overall scheme of the > > > kernel, right? What's wrong with using the usb subdirectory like all > > > > Agree, it wasn't the right thing to do at the first place. But now > > changing it adds support burden, because people very often refer to the > > old information on the internet which no longer matches to the new > > location. Basically, it is a cost of ABI change. > > What information says that /sys/kernel/debug/mdev/ is the location for > this? Is it in-kernel? No, they are not in-kernel, but many places mainly on https://e2e.ti.com and http://processors.wiki.ti.com. It basically says to get musb regdump, cat /sys/kernel/debug/musb-hdrc.{0,1}/regdump, or to enter test mode, do echo _testmode_ > /sys/kernel/debug/musb-hdrc.{0,1}/testmode... > > > other USB drivers use (after this patch series is merged)? That feels > > > like a much more "sane" way to handle the wide-open debugfs namespace. > > > > Though I commented on this musb patch, my opinion is for this whole > > series, either drop the whole series or apply the whole series. > > I've applied all but this one and 2 others that did not build properly. Okay. > > > Yes, there are no rules when it comes to debugfs file names and > > > locations, but let's try to be sane please. > > > > Fine with me. I can still support questions such as "can't open > > /sys/kernel/debug/musb-hdrc.0/testmode: No such file or directory". > > What tool looks for that? I wrote a usb diagnosis tool called chkusb.sh, which basically checks usb related information in - /proc/config.gz - /lib/modules/`uname -r`/kernel/drivers/ - /proc/device-tree/ - /sys/device/ - /sys/kernel/debug/ So whenever I got a report on e2e.ti.com saying that usb doesn't work, I just post this script and get a log which would give a clue if there was any fundamental mistake in kernel configuration or deployment. But not a big issue here for this tool regarding this patch set, I can update the script to check both locations - /sys/kernel/debug/ and /sys/kernel/debug/usb/. -Bin.
