hi David: 2014-07-07 23:06 GMT+08:00 David Laight <David.Laight@xxxxxxxxxx>: > From: Lars Melin > ... >> sgread is not included in BusyBox but you should have "touch". >> Create a dummy file on the disk and let cron touch it every 4 minutes. > > You don't need 'touch' a shell redirect eg ": >file" will do open(..., O_CREAT|O_TRUNC). > However that still might not force an actual disc access. > > In any case you really only want to do a read, doing a write will kill the NAND memory. actually I have searched the scsi/usb layer for possible dummy read, even read sector 0 is fine, but in vain. I found the read a. determined by VFS -> block layer, b. Block layer put it in queue c. call scsi pre-queue function to usb layer. That mean if I try to read sector from usb devices, I have to create a queue and follow above b) and c) rule. is there any already kernel API I can use? sincerely appreciate all yours help, -- 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
