ide: cleanup ide_build_dmatable()

- use for_each_sg()
- move printing 'DMA table too small' message below use_pio_instead label
- merge '64KB bug' comment with function documentation
- fix intendation

There should be no functional changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c
index 83885ba..4d212b8 100644 (file)
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -153,8 +153,11 @@ EXPORT_SYMBOL_GPL(ide_build_sglist);
  *
  *     ide_build_dmatable() prepares a dma request. We map the command
  *     to get the pci bus addresses of the buffers and then build up
- *     the PRD table that the IDE layer wants to be fed. The code
- *     knows about the 64K wrap bug in the CS5530.
+ *     the PRD table that the IDE layer wants to be fed.
+ *
+ *     Most chipsets correctly interpret a length of 0x0000 as 64KB,
+ *     but at least one (e.g. CS5530) misinterprets it as zero (!).
+ *     So we break the 64KB entry into two 32KB entries instead.
  *
  *     Returns the number of built PRD entries if all went okay,
  *     returns 0 otherwise.
@@ -171,15 +174,12 @@ int ide_build_dmatable (ide_drive_t *drive, struct request *rq)
        int i;
        struct scatterlist *sg;
 
-       hwif->sg_nents = i = ide_build_sglist(drive, rq);
-
-       if (!i)
+       hwif->sg_nents = ide_build_sglist(drive, rq);
+       if (hwif->sg_nents == 0)
                return 0;
 
-       sg = hwif->sg_table;
-       while (i) {
-               u32 cur_addr;
-               u32 cur_len;
+       for_each_sg(hwif->sg_table, sg, hwif->sg_nents, i) {
+               u32 cur_addr, cur_len, xcount, bcount;
 
                cur_addr = sg_dma_address(sg);
                cur_len = sg_dma_len(sg);
@@ -191,40 +191,27 @@ int ide_build_dmatable (ide_drive_t *drive, struct request *rq)
                 */
 
                while (cur_len) {
-                       if (count++ >= PRD_ENTRIES) {
-                               printk(KERN_ERR "%s: DMA table too small\n", drive->name);
+                       if (count++ >= PRD_ENTRIES)
                                goto use_pio_instead;
-                       } else {
-                               u32 xcount, bcount = 0x10000 - (cur_addr & 0xffff);
-
-                               if (bcount > cur_len)
-                                       bcount = cur_len;
-                               *table++ = cpu_to_le32(cur_addr);
-                               xcount = bcount & 0xffff;
-                               if (is_trm290)
-                                       xcount = ((xcount >> 2) - 1) << 16;
-                               else if (xcount == 0x0000) {
-       /* 
-        * Most chipsets correctly interpret a length of 0x0000 as 64KB,
-        * but at least one (e.g. CS5530) misinterprets it as zero (!).
-        * So here we break the 64KB entry into two 32KB entries instead.
-        */
-                                       if (count++ >= PRD_ENTRIES) {
-                                               printk(KERN_ERR "%s: DMA table too small\n", drive->name);
-                                               goto use_pio_instead;
-                                       }
-                                       *table++ = cpu_to_le32(0x8000);
-                                       *table++ = cpu_to_le32(cur_addr + 0x8000);
-                                       xcount = 0x8000;
-                               }
-                               *table++ = cpu_to_le32(xcount);
-                               cur_addr += bcount;
-                               cur_len -= bcount;
+
+                       bcount = 0x10000 - (cur_addr & 0xffff);
+                       if (bcount > cur_len)
+                               bcount = cur_len;
+                       *table++ = cpu_to_le32(cur_addr);
+                       xcount = bcount & 0xffff;
+                       if (is_trm290)
+                               xcount = ((xcount >> 2) - 1) << 16;
+                       if (xcount == 0x0000) {
+                               if (count++ >= PRD_ENTRIES)
+                                       goto use_pio_instead;
+                               *table++ = cpu_to_le32(0x8000);
+                               *table++ = cpu_to_le32(cur_addr + 0x8000);
+                               xcount = 0x8000;
                        }
+                       *table++ = cpu_to_le32(xcount);
+                       cur_addr += bcount;
+                       cur_len -= bcount;
                }
-
-               sg = sg_next(sg);
-               i--;
        }
 
        if (count) {
@@ -233,14 +220,14 @@ int ide_build_dmatable (ide_drive_t *drive, struct request *rq)
                return count;
        }
 
-       printk(KERN_ERR "%s: empty DMA table?\n", drive->name);
-
 use_pio_instead:
+       printk(KERN_ERR "%s: %s\n", drive->name,
+               count ? "DMA table too small" : "empty DMA table?");
+
        ide_destroy_dmatable(drive);
 
        return 0; /* revert to PIO for this request */
 }
-
 EXPORT_SYMBOL_GPL(ide_build_dmatable);
 #endif