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>

1 files changed, 30 insertions, 43 deletions

diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c
index 83885ba0496c..4d212b867c35 100644
--- 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