serverworks: fix CSB6 tuning logic

Problem noticed by Joe Zbiciak, see http://kerneltrap.org/node/8252 for details. On CSB6 the driver is using BIOS settings and not programming DMA/PIO timings itself. However the logic was completely broken and resulted in wrong timings being silently allowed (instead of being corrected by the driver). This bug would explain some data corruption/timeout issues with Serverworks MegaIDE in RAID mode that Alan Cox has fixed recently with: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=2074a106f52b6371885afbd714e929d60d0e3f64 For 2.6.23 we may be better off with completely switching the driver to always programming timings (libata pata_serverworks.c driver is doing things this way and there were no problems reported so far) but for 2.6.22 lets fix the bug in the simplest and the least intrusive way. Cc: Alan Cox <[email protected]> Signed-off-by: Bartlomiej Zolnierkiewicz <[email protected]>
chewitt · Jun 8, 2007 · 1abb8a8 · 1abb8a8
1 parent ed84fad
commit 1abb8a8
Showing 1 changed file with 27 additions and 13 deletions.
diff --git a/drivers/ide/pci/serverworks.c b/drivers/ide/pci/serverworks.c
@@ -1,5 +1,5 @@
 /*
- * linux/drivers/ide/pci/serverworks.c		Version 0.10	Jun 2 2007
+ * linux/drivers/ide/pci/serverworks.c		Version 0.11	Jun 2 2007
  *
  * Copyright (C) 1998-2000 Michel Aubry
  * Copyright (C) 1998-2000 Andrzej Krzysztofowicz
@@ -176,35 +176,49 @@ static int svwks_tune_chipset (ide_drive_t *drive, u8 xferspeed)
 				return 0;
 			} else if ((dma_timing) &&
 				   ((dma_stat&(1<<(5+unit)))==(1<<(5+unit)))) {
-				u8 dmaspeed = dma_timing;
+				u8 dmaspeed;
 
-				if ((dmaspeed & 0x20) == 0x20)
+				switch (dma_timing & 0x77) {
+				case 0x20:
 					dmaspeed = XFER_MW_DMA_2;
-				else if ((dmaspeed & 0x21) == 0x21)
+					break;
+				case 0x21:
 					dmaspeed = XFER_MW_DMA_1;
-				else if ((dmaspeed & 0x77) == 0x77)
+					break;
+				case 0x77:
 					dmaspeed = XFER_MW_DMA_0;
-				else
+					break;
+				default:
 					goto dma_pio;
+				}
+
 				drive->current_speed = drive->init_speed = dmaspeed;
 				return 0;
 			}
 dma_pio:
 			if (pio_timing) {
-				u8 piospeed = pio_timing;
+				u8 piospeed;
 
-				if ((piospeed & 0x20) == 0x20)
+				switch (pio_timing & 0x7f) {
+				case 0x20:
 					piospeed = XFER_PIO_4;
-				else if ((piospeed & 0x22) == 0x22)
+					break;
+				case 0x22:
 					piospeed = XFER_PIO_3;
-				else if ((piospeed & 0x34) == 0x34)
+					break;
+				case 0x34:
 					piospeed = XFER_PIO_2;
-				else if ((piospeed & 0x47) == 0x47)
+					break;
+				case 0x47:
 					piospeed = XFER_PIO_1;
-				else if ((piospeed & 0x5d) == 0x5d)
+					break;
+				case 0x5d:
 					piospeed = XFER_PIO_0;
-				else
+					break;
+				default:
 					goto oem_setup_failed;
+				}
+
 				drive->current_speed = drive->init_speed = piospeed;
 				return 0;
 			}