Ticket #316: ata-packet-detect.diff

uspace/srv/bd/ata_bd/ata_bd.c

@@ -370 +370 @@
         uint8_t model[40];
         ata_inquiry_data_t inq_data;
         uint16_t w;
-        uint8_t c;
+        uint8_t c, bc_high, bc_low;
         size_t pos, len;
         int rc;
         unsigned i;
@@ -386 +386 @@
                 d->dev_type = ata_reg_dev;
         } else if (rc == EIO) {
                 /*
-                 * There is something, but not a register device.
-                 * It could be a packet device.
+                 * There is something, but not a register device. Check to see
+                 * whether the IDENTIFY command left the packet signature in
+                 * the registers in case this is a packet device.
+                 *
+                 * According to the ATA specification, the LBA low and
+                 * interrupt reason registers should be set to 0x01. However,
+                 * there are many devices that do not follow this and only set
+                 * the byte count registers. So, only check these.
                  */
-                rc = identify_pkt_dev(disk_id, &idata);
-                if (rc == EOK) {
-                        /* We have a packet device. */
-                        d->dev_type = ata_pkt_dev;
+                bc_high = pio_read_8(&cmd->cylinder_high);
+                bc_low = pio_read_8(&cmd->cylinder_low);
+
+                if (bc_high == 0xEB && bc_low == 0x14) {
+                        rc = identify_pkt_dev(disk_id, &idata);
+                        if (rc == EOK) {
+                                /* We have a packet device. */
+                                d->dev_type = ata_pkt_dev;
+                        } else {
+                                return EIO;
+                        }
                 } else {
                         /* Nope. Something's there, but not recognized. */
                         return EIO;
@@ -565 +578 @@
         pio_write_8(&cmd->drive_head, drv_head);
 
         /*
-         * This is where we would most likely expect a non-existing device to
-         * show up by not setting SR_DRDY.
+         * Do not wait for DRDY to be set in case this is a packet device.
+         * We determine whether the device is present by waiting for DRQ to be
+         * set after issuing the command.
          */
-        if (wait_status(SR_DRDY, ~SR_BSY, NULL, TIMEOUT_PROBE) != EOK)
+        if (wait_status(0, ~SR_BSY, NULL, TIMEOUT_PROBE) != EOK)
                 return ETIMEOUT;
 
         pio_write_8(&cmd->command, CMD_IDENTIFY_DRIVE);
@@ -576 +590 @@
         if (wait_status(0, ~SR_BSY, &status, TIMEOUT_PROBE) != EOK)
                 return ETIMEOUT;
 
+        /*
+         * If ERR is set, this may be a packet device, so return EIO to cause
+         * the caller to check for one.
+         */
+        if ((status & SR_ERR) != 0) {
+                return EIO;
+        }
+
+        if (wait_status(SR_DRQ, ~SR_BSY, &status, TIMEOUT_PROBE) != EOK)
+                return ETIMEOUT;
+
         /* Read data from the disk buffer. */
 
-        if ((status & SR_DRQ) != 0) {
-                for (i = 0; i < identify_data_size / 2; i++) {
-                        data = pio_read_16(&cmd->data_port);
-                        ((uint16_t *) buf)[i] = data;
-                }
-        }
-
-        if ((status & SR_ERR) != 0) {
-                return EIO;
+        for (i = 0; i < identify_data_size / 2; i++) {
+                data = pio_read_16(&cmd->data_port);
+                ((uint16_t *) buf)[i] = data;
         }
 
         return EOK;