On Tue, 2006-06-27 at 16:07 +0800, dezheng shen wrote:
> Dear all:
> This email was originally posted on linux-kernel but I didn't get any
> response yet so that I post it to this linux-scsi again. Hope that we
> can get reply soon.
Sorry for the delay, I've been a bit busy with KS/OLS and other things.
This, I'm afraid is basically the killer for scsi:
> static int wb_process_scsi_cmd(Scsi_Cmnd * cmd)
> {
> unsigned long flags;
> wb_host_data_t *host_data;
> ENTER();
>
> host_data = g_wb_host_data;
> wb_chk_valid_medium(host_data);
>
> wb_unit_ready(cmd);
>
> switch (cmd->cmnd[0]) {
>
> case START_STOP:
> WB_PRINTK_SCSI("START_STOP\n");
> wb_scsi_start_stop(cmd);
> break;
>
> case REQUEST_SENSE:
> WB_PRINTK_SCSI("REQUEST_SENSE\n");
> wb_scsi_request_sense(cmd);
> break;
>
> case ALLOW_MEDIUM_REMOVAL:
> WB_PRINTK_SCSI("ALLOW_MEDIUM_REMOVAL\n");
> wb_scsi_allow_medium_removal(cmd);
> break;
>
> case TEST_UNIT_READY:
> WB_PRINTK_SCSI("TEST_UNIT_READY\n");
> wb_scsi_test_unit_ready(cmd);
> break;
>
> case INQUIRY:
> WB_PRINTK_SCSI("INQUIRY\n");
> wb_scsi_inquiry(cmd);
> break;
>
> case READ_6:
> WB_PRINTK_ERROR_SCSI("READ_6\n");
> break;
>
> case READ_10:
> WB_PRINTK_SCSI("READ_10\n");
> wb_scsi_read_wrt(cmd, TRUE);
> break;
>
> case WRITE_6:
> WB_PRINTK_ERROR_SCSI("WRITE_6\n");
> break;
>
> case WRITE_10:
> WB_PRINTK_SCSI("WRITE_10\n");
> wb_scsi_read_wrt(cmd, FALSE);
> break;
>
> // MODE_SENSE is 6-byte command
> case MODE_SENSE:
> WB_PRINTK_SCSI("MODE_SENSE\n");
> wb_scsi_mode_sense(cmd);
> break;
>
> case READ_CAPACITY:
> WB_PRINTK_SCSI("READ_CAPACITY\n");
> wb_scsi_read_capacity(cmd);
> break;
>
> case FORMAT_UNIT:
> WB_PRINTK_SCSI("FORMAT_UNIT\n");
> wb_scsi_format_unit(cmd);
> break;
>
> // haven't handled all necessary cases yet
> default:
> WB_PRINTK_ERROR_SCSI("UNKNOWN command(0x%x)\n", cmd->cmnd[0]);
> wb_make_sense_buffer(cmd, ILLEGAL_REQUEST, 0x20, 0x00);
> cmd->result =
> WB_CMD_RESULT(DID_OK, COMMAND_COMPLETE, CHECK_CONDITION);
> break;
> } // end switch
>
> spin_lock_irqsave(g_wb_host->host_lock, flags);
> cmd->scsi_done(cmd);
> spin_unlock_irqrestore(g_wb_host->host_lock, flags);
>
> LEAVE();
> return 0;
> }
It means there's no actual SCSI command processor anywhere in the
device. You're simply using the SCSI subsystem as a passthrough. We
really try to discourage this unless the actual underlying device speaks
SCSI. Ideally, a driver like this should fit into the existing mmc/sd
subsystem, but if it doesn't, it should be written as a simple block
driver rather than doing the unnecessary round trip conversion to SCSI
protocols and back.
James
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