stable inclusion
from stable-v5.10.122
commit 0248a8c844a497f6b129d9b11adbfaaeee117c8a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5W6OE

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0248a8c844a497f6b129d9b11adbfaaeee117c8a

--------------------------------

commit 72aad489 upstream.

The {dma|pio}_mode sysfs files are incorrectly documented as having a
list of the supported DMA/PIO transfer modes, while the corresponding
fields of the *struct* ata_device hold the transfer mode IDs, not masks.

To match these docs, the {dma|pio}_mode (and even xfer_mode!) sysfs
files are handled by the ata_bitfield_name_match() macro which leads to
reading such kind of nonsense from them:

$ cat /sys/class/ata_device/dev3.0/pio_mode
XFER_UDMA_7, XFER_UDMA_6, XFER_UDMA_5, XFER_UDMA_4, XFER_MW_DMA_4,
XFER_PIO_6, XFER_PIO_5, XFER_PIO_4, XFER_PIO_3, XFER_PIO_2, XFER_PIO_1,
XFER_PIO_0

Using the correct ata_bitfield_name_search() macro fixes that:

$ cat /sys/class/ata_device/dev3.0/pio_mode
XFER_PIO_4

While fixing the file documentation, somewhat reword the {dma|pio}_mode
file doc and add a note about being mostly useful for PATA devices to
the xfer_mode file doc...

Fixes: d9027470 ("[libata] Add ATA transport class")
Signed-off-by: NSergey Shtylyov <s.shtylyov@omp.ru>
Cc: stable@vger.kernel.org
Signed-off-by: NDamien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>