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
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -153,8 +153,11 @@
*
* 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 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 @@
*/
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 @@
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