On 6/14/09, Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote: > On 06/12/2009 03:54 PM, Ramya Desai wrote: > > On 6/12/09, Jeff Garzik <jeff@xxxxxxxxxx> wrote: > >> Ramya Desai wrote: > >> > >>> Dear Experts, > >>> > >>> I am writing my mass storage class driver for my custom USB device. > >>> My device is capable of queuing the commands that are issued to it. > >>> So, I wanted to send the second command from my driver even before the > >>> completion of first command. > >>> To do this I wanted to return the PENDING status to the SCSI layer > >>> immediately after receiving the command. > >>> > >> Simply queue as many commands as possible to your hardware, and complete > >> them when they are done. Use can_queue or scsi_adjust_queue_depth() to set > >> queueing limits. > >> > >> Jeff > > > > I used can_queue to change the queue depth to 5, but I am not getting > > the next command until I finish (Done) the first command. I wanted the > > second command to come to my driver, even before first command > > finishes. > > > > -RD > > > If you are using the existing USB mass storage infrastructure then > it will not work. This is because all commands are issued from a > thread per host, which does a synchronous execution of one command > at a time. In fact it does not even have a Q, but a global one cmnd > pointer per host. And therefor sets can_queue to 1. > > Are you using the existing USB infrastructure? > > > Boaz > I am replacing the default USB mass storage driver with the one I am developing. But I am using the default SCSI and USB stack provided by Linux. So is there any another way to make my driver asynchronous? -RD -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
