On Mon, 27 Jul 2015, Giulio Bernardi wrote: > Sorry for the late reply, but it took me a little bit to recompile the kernel > (my laptop is slow) and I was not able to obtain any meaningful results (please > note I know nothing about kernel internals). > > However, i filled scsi_sequential_lun_scan() with printk's but none of them > appeared (yes, I did echo 7 > /proc/sys/kernel/printk). > So I enabled logging for SCSI scan bus (echo 448 > > /proc/sys/dev/scsi/logging_level) and I did not see message "scsi scan: > Sequential scan\n" appearing. So I thought scsi_sequential_lun_scan() was not > being called. That's strange. If you look at __scsi_scan_target(), you'll see that the code calls scsi_probe_and_add_lun() for LUN 0, then it calls scsi_report_lun_scan() (which should return 1), and then it calls scsi_sequential_lun_scan(). You should check that scsi_report_lun_scan() really does return 1. If it returns 0 instead (because BLIST_NOLUN is set in bflags or for any other reason), that would cause the behavior you see. > So I recompiled usb_storage with CONFIG_USB_STORAGE_DEBUG=y, and I got this (it > looks like it is obtaining the max lun from some other routine?). Yes, that comes from usb_stor_Bulk_max_lun() in drivers/usb/storage/transport.c. > ----8<--------------------------------------------------------------- > usb 2-2: new high-speed USB device number 4 using ehci-pci > usb 2-2: New USB device found, idVendor=152d, idProduct=1567 > usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=5 > usb 2-2: Product: JMS56x Series > usb 2-2: Manufacturer: JMicron > usb 2-2: SerialNumber: DB9876543211166 > usb 2-2: UAS is blacklisted for this device, using usb-storage instead > usb-storage 2-2:1.0: USB Mass Storage device detected > Vendor: 0x152d, Product: 0x1567, Revision: 0x0101 > Interface Subclass: 0x06, Protocol: 0x50 > usb-storage 2-2:1.0: Quirks match for vid 152d pid 1567: 800000 > Transport: Bulk > Protocol: Transparent SCSI > scsi host7: usb-storage 2-2:1.0 > usb-storage 2-2:1.0: waiting for device to settle before scanning > *** thread sleeping > usb-storage 2-2:1.0: starting scan > rq=fe rqtype=a1 value=0000 index=00 len=1 > GetMaxLUN command result is 1, data is 0 > usb-storage 2-2:1.0: scan complete > scsi host7: scsi_scan_host_selected: <4294967295:4294967295:18446744073709551615> > scsi 7:0:0:0: scsi scan: INQUIRY pass 1 length 36 > ----8<--------------------------------------------------------------- > > Does this make any sense for you? I am a bit lost. Only the last two lines in this log are relevant, and they don't contain any new information. Alan Stern -- 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
