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Date: Sat, 30 Dec 2000 19:06:05 +0200
From: Tommi Virtanen <tv-nospam-0a4282@debian.org>
To: linux-kernel@vger.kernel.org
Cc: Taisuke Yamada <tai@imasy.or.jp>
Subject: Re: [PATCH] Large "clipped" IDE disk support for 2.4 when using old BIOS (fixed patch)
Message-ID: <20001230190605.A17073@hq.yok.utu.fi>
In-Reply-To: <200011181930.eAIJUYA01883@research.imasy.or.jp>
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In-Reply-To: <200011181930.eAIJUYA01883@research.imasy.or.jp>; from tai@imasy.or.jp on Sat, Nov 18, 2000 at 09:32:26PM +0200
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On Sat, Nov 18, 2000 at 09:32:26PM +0200, Taisuke Yamada wrote:
> Earlier this month, I had sent in a patch to 2.2.18pre17 (with
> IDE-patch from http://www.linux-ide.org/ applied) to add support
> for IDE disk larger than 32GB, even if the disk required "clipping"
> to reduce apparent disk size due to BIOS limitation.
[..]
> Now I'm moving to 2.4-based system, and so ported the patch to
> 2.4-test10. It also applies cleanly to 2.4-test11.

	Well, the patch in the message didn't apply cleanly and
	had some problems, as discussed in the rest of the thread.
	As no one seems to have posted an updated patch, here
	goes. This works nicely for my Maxtor 81.9GB HDD.

--- linux-2.4.0-test13-pre5/drivers/ide/ide-disk.c	Fri Oct 27 09:35:48 2000
+++ linux/drivers/ide/ide-disk.c	Thu Dec 28 22:49:18 2000
@@ -513,24 +513,149 @@
 			current_capacity(drive));
 }
 
+
+/*
+ * Tests if the drive supports Host Protected Area feature.
+ * Returns true if supported, false otherwise.
+ */
+static inline int idedisk_supports_host_protected_area(ide_drive_t *drive)
+{
+    int flag = (drive->id->command_set_1 & 0x0400) ? 1 : 0;
+    printk("%s: host protected area => %d\n", drive->name, flag);
+    return flag;
+}
+
+/*
+ * Queries for true maximum capacity of the drive.
+ * Returns maximum LBA address (> 0) of the drive, 0 if failed.
+ */
+static unsigned long idedisk_read_native_max_address(ide_drive_t *drive)
+{
+    byte args[7];
+    unsigned long addr = 0;
+
+    printk("%s: checking for max native LBA...\n", drive->name);
+
+    /* Create IDE/ATA command request structure
+     *
+     * NOTE: I'm not sure if I can safely use IDE_*_OFFSET macro
+     *       here...For real ATA command structure, offset for IDE
+     *       command is 7, but in IDE driver, it needs to be at 0th
+     *       index (same goes for IDE status offset below). Hmm...
+     */
+    args[0]                  = 0xf8; /* READ_NATIVE_MAX - see ATA spec */
+    args[IDE_FEATURE_OFFSET] = 0x00;
+    args[IDE_NSECTOR_OFFSET] = 0x00;
+    args[IDE_SECTOR_OFFSET]  = 0x00;
+    args[IDE_LCYL_OFFSET]    = 0x00;
+    args[IDE_HCYL_OFFSET]    = 0x00;
+    args[IDE_SELECT_OFFSET]  = 0x40;
+
+    /* submit command request - if OK, read current max LBA value */
+    if (ide_wait_cmd_task(drive, args) == 0) {
+        if ((args[0] & 0x01) == 0) {
+            addr = ((args[IDE_SELECT_OFFSET] & 0x0f) << 24)
+                 | ((args[IDE_HCYL_OFFSET]         ) << 16)
+                 | ((args[IDE_LCYL_OFFSET]         ) <<  8)
+                 | ((args[IDE_SECTOR_OFFSET]       ));
+        }
+    }
+
+    printk("%s: max native LBA is %lu\n", drive->name, addr);
+
+    return addr;
+}
+
+/*
+ * Sets maximum virtual LBA address of the drive.
+ * Returns new maximum virtual LBA address (> 0) or 0 on failure.
+ */
+static unsigned long idedisk_set_max_address(ide_drive_t  *drive,
+                         unsigned long addr_req)
+{
+    byte args[7];
+    unsigned long addr_set = 0;
+
+    printk("%s: (un)clipping max LBA...\n", drive->name);
+
+    /* Create IDE/ATA command request structure
+     *
+     * NOTE: I'm not sure if I can safely use IDE_*_OFFSET macro
+     *       here...For real ATA command structure, offset for IDE
+     *       command is 7, but in IDE driver, it needs to be at 0th
+     *       index (same goes for IDE status offset below). Hmm...
+     */
+    args[0]                  = 0xf9; /* SET_MAX - see ATA spec */
+	args[IDE_FEATURE_OFFSET] = 0x00;
+    args[IDE_NSECTOR_OFFSET] = 0x00;
+    args[IDE_SECTOR_OFFSET]  = ((addr_req      ) & 0xff);
+    args[IDE_LCYL_OFFSET]    = ((addr_req >>  8) & 0xff);
+    args[IDE_HCYL_OFFSET]    = ((addr_req >> 16) & 0xff);
+    args[IDE_SELECT_OFFSET]  = ((addr_req >> 24) & 0x0f) | 0x40;
+
+    /* submit command request - if OK, read new max LBA value */
+    if (ide_wait_cmd_task(drive, args) == 0) {
+        if ((args[0] & 0x01) == 0) {
+            addr_set = ((args[IDE_SELECT_OFFSET] & 0x0f) << 24)
+                 | ((args[IDE_HCYL_OFFSET]         ) << 16)
+                 | ((args[IDE_LCYL_OFFSET]         ) <<  8)
+                 | ((args[IDE_SECTOR_OFFSET]       ));
+        }
+    }
+
+    printk("%s: max LBA (un)clipped to %lu\n", drive->name, addr_set);
+
+    return addr_set;
+}
+
 /*
  * Compute drive->capacity, the full capacity of the drive
  * Called with drive->id != NULL.
+ *
+ * To compute capacity, this uses either of
+ *
+ *    1. CHS value set by user       (whatever user sets will be trusted)
+ *    2. LBA value from target drive (require new ATA feature)
+ *    3. LBA value from system BIOS  (new one is OK, old one may break)
+ *    4. CHS value from system BIOS  (traditional style)
+ *
+ * in above order (i.e., if value of higher priority is available,
+ * rest of the values are ignored).
  */
 static void init_idedisk_capacity (ide_drive_t  *drive)
 {
+    unsigned long      hd_max;
+    unsigned long      hd_cap = drive->cyl * drive->head * drive->sect;
+    int                is_lba = 0;
+
 	struct hd_driveid *id = drive->id;
-	unsigned long capacity = drive->cyl * drive->head * drive->sect;
 
-	drive->select.b.lba = 0;
+    /* Unless geometry is given by user, use autodetected value */
+    if (! drive->forced_geom) {
+        /* If BIOS LBA geometry is available, use it */
+        if ((id->capability & 2) && lba_capacity_is_ok(id)) {
+            hd_cap = id->lba_capacity;
+            is_lba = 1;
+        }
 
-	/* Determine capacity, and use LBA if the drive properly supports it */
-	if ((id->capability & 2) && lba_capacity_is_ok(id)) {
-		capacity = id->lba_capacity;
-		drive->cyl = capacity / (drive->head * drive->sect);
-		drive->select.b.lba = 1;
+        /* If new ATA feature is supported, try using it */
+        if (idedisk_supports_host_protected_area(drive)) {
+            hd_max = idedisk_read_native_max_address(drive);
+            hd_max = idedisk_set_max_address(drive, hd_max);
+
+            if (hd_max > 0) {
+                hd_cap = hd_max+1;
+                is_lba = 1;
+            }
+        }
 	}
-	drive->capacity = capacity;
+
+    printk("%s: lba = %d, cap = %lu\n", drive->name, is_lba, hd_cap);
+
+    /* update parameters with fetched results */
+    drive->select.b.lba = is_lba;
+    drive->capacity     = hd_cap;
+    drive->cyl          = hd_cap / (drive->head * drive->sect);
 }
 
 static unsigned long idedisk_capacity (ide_drive_t  *drive)

-- 
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