ide: DMA reporting and validity checking fixes (take 3)

* ide_xfer_verbose() fixups:
  - beautify returned mode names
  - fix PIO5 reporting
  - make it return 'const char *'

* Change printk() level from KERN_DEBUG to KERN_INFO in ide_find_dma_mode().

* Add ide_id_dma_bug() helper based on ide_dma_verbose() to check for invalid
  DMA info in identify block.

* Use ide_id_dma_bug() in ide_tune_dma() and ide_driveid_update().

  As a result DMA won't be tuned or will be disabled after tuning if device
  reports inconsistent info about enabled DMA mode (ide_dma_verbose() does the
  same checks while the IDE device is probed by ide-{cd,disk} device driver).

* Remove no longer needed ide_dma_verbose().

This patch should fix the following problem with out-of-sync IDE messages
reported by Nick Warne:

       hdd: ATAPI 48X DVD-ROM DVD-R-RAM CD-R/RW drive, 2048kB Cache<7>hdd:
       skipping word 93 validity check
        , UDMA(66)

and later debugged by Mark Lord to be caused by:

        ide_dma_verbose()
                printk( ... "2048kB Cache");
        eighty_ninty_three()
                printk(KERN_DEBUG "%s: skipping word 93 validity check\n");
        ide_dma_verbose()
                printk(", UDMA(66)"

Please note that as a result ide-{cd,disk} device drivers won't report the
DMA speed used but this is intended since now DMA mode being used is always
reported by IDE core code.

v2:
* fixes suggested by Randy:
  - use KERN_CONT for printk()-s in ide-{cd,disk}.c
  - don't remove argument name from ide_xfer_verbose() declaration

v3:
* Remove incorrect check for (id->field_valid & 1) from ide_id_dma_bug()
  (spotted by Sergei).

* "XFER SLOW" -> "PIO SLOW" in ide_xfer_verbose() (suggested by Sergei).

* Fix ide_find_dma_mode() to report the correct mode ('mode' after being
  limited by 'req_mode').

Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Nick Warne <nick@ukfsn.org>
Cc: Mark Lord <lkml@rtr.ca>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-disk.c b/drivers/ide/ide-disk.c
index 00123d99..b77c849 100644
--- a/drivers/ide/ide-disk.c
+++ b/drivers/ide/ide-disk.c
@@ -961,11 +961,8 @@
 	if (id->buf_size)
 		printk (" w/%dKiB Cache", id->buf_size/2);
 
-	printk(", CHS=%d/%d/%d", 
-	       drive->bios_cyl, drive->bios_head, drive->bios_sect);
-	if (drive->using_dma)
-		ide_dma_verbose(drive);
-	printk("\n");
+	printk(KERN_CONT ", CHS=%d/%d/%d\n",
+			 drive->bios_cyl, drive->bios_head, drive->bios_sect);
 
 	/* write cache enabled? */
 	if ((id->csfo & 1) || (id->cfs_enable_1 & (1 << 5)))