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Commit 14c123f3 authored by Bartlomiej Zolnierkiewicz's avatar Bartlomiej Zolnierkiewicz
Browse files

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: default avatarBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
parent c19f7f22

drivers/ide/ide-dma.c

+30 −43
Original line number Diff line number Diff line
@@ -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);
@@ -191,28 +191,19 @@ 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);



			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);

			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;
@@ -223,24 +214,20 @@ int ide_build_dmatable (ide_drive_t *drive, struct request *rq) 
		}

	}



		sg = sg_next(sg);

		i--;

	}



	if (count) {

		if (!is_trm290)

			*--table |= cpu_to_le32(0x80000000);

		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