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ide: cleanup ide_build_dmatable()

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- 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>
This commit is contained in:
Bartlomiej Zolnierkiewicz
2008-10-13 21:39:47 +02:00
parent c19f7f226b
commit 14c123f371
1 changed files with 29 additions and 42 deletions
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45
drivers/ide/ide-dma.c
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@@ -153,8 +153,11 @@ EXPORT_SYMBOL_GPL(ide_build_sglist);
* *
* ide_build_dmatable() prepares a dma request. We map the command * ide_build_dmatable() prepares a dma request. We map the command
* to get the pci bus addresses of the buffers and then build up * 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 * the PRD table that the IDE layer wants to be fed.
* knows about the 64K wrap bug in the CS5530. *
* 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 the number of built PRD entries if all went okay,
* returns 0 otherwise. * returns 0 otherwise.
@@ -171,15 +174,12 @@ int ide_build_dmatable (ide_drive_t *drive, struct request *rq)
int i; int i;
struct scatterlist *sg; struct scatterlist *sg;
hwif->sg_nents = i = ide_build_sglist(drive, rq); hwif->sg_nents = ide_build_sglist(drive, rq);
if (hwif->sg_nents == 0)
if (!i)
return 0; return 0;
sg = hwif->sg_table; for_each_sg(hwif->sg_table, sg, hwif->sg_nents, i) {
while (i) { u32 cur_addr, cur_len, xcount, bcount;
u32 cur_addr;
u32 cur_len;
cur_addr = sg_dma_address(sg); cur_addr = sg_dma_address(sg);
cur_len = sg_dma_len(sg); cur_len = sg_dma_len(sg);
@@ -191,28 +191,19 @@ int ide_build_dmatable (ide_drive_t *drive, struct request *rq)
*/ */
while (cur_len) { while (cur_len) {
if (count++ >= PRD_ENTRIES) { if (count++ >= PRD_ENTRIES)
printk(KERN_ERR "%s: DMA table too small\n", drive->name);
goto use_pio_instead; goto use_pio_instead;
} else {
u32 xcount, bcount = 0x10000 - (cur_addr & 0xffff);
bcount = 0x10000 - (cur_addr & 0xffff);
if (bcount > cur_len) if (bcount > cur_len)
bcount = cur_len; bcount = cur_len;
*table++ = cpu_to_le32(cur_addr); *table++ = cpu_to_le32(cur_addr);
xcount = bcount & 0xffff; xcount = bcount & 0xffff;
if (is_trm290) if (is_trm290)
xcount = ((xcount >> 2) - 1) << 16; xcount = ((xcount >> 2) - 1) << 16;
else if (xcount == 0x0000) { if (xcount == 0x0000) {
/* if (count++ >= PRD_ENTRIES)
* 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; goto use_pio_instead;
}
*table++ = cpu_to_le32(0x8000); *table++ = cpu_to_le32(0x8000);
*table++ = cpu_to_le32(cur_addr + 0x8000); *table++ = cpu_to_le32(cur_addr + 0x8000);
xcount = 0x8000; xcount = 0x8000;
@@ -223,24 +214,20 @@ int ide_build_dmatable (ide_drive_t *drive, struct request *rq)
} }
} }
sg = sg_next(sg);
i--;
}
if (count) { if (count) {
if (!is_trm290) if (!is_trm290)
*--table |= cpu_to_le32(0x80000000); *--table |= cpu_to_le32(0x80000000);
return count; return count;
} }
printk(KERN_ERR "%s: empty DMA table?\n", drive->name);
use_pio_instead: use_pio_instead:
printk(KERN_ERR "%s: %s\n", drive->name,
count ? "DMA table too small" : "empty DMA table?");
ide_destroy_dmatable(drive); ide_destroy_dmatable(drive);
return 0; /* revert to PIO for this request */ return 0; /* revert to PIO for this request */
} }
EXPORT_SYMBOL_GPL(ide_build_dmatable); EXPORT_SYMBOL_GPL(ide_build_dmatable);
#endif #endif