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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Sergey Shtylyov <s.shtylyov@omp.ru>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>
Subject: [PATCH 4.9 160/167] ata: libata-transport: fix {dma|pio|xfer}_mode sysfs files
Date:   Mon, 13 Jun 2022 12:10:34 +0200
Message-Id: <20220613094918.497423809@linuxfoundation.org>
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From: Sergey Shtylyov <s.shtylyov@omp.ru>

commit 72aad489f992871e908ff6d9055b26c6366fb864 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: d9027470b886 ("[libata] Add ATA transport class")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/ABI/testing/sysfs-ata |    5 +++--
 drivers/ata/libata-transport.c      |    2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

--- a/Documentation/ABI/testing/sysfs-ata
+++ b/Documentation/ABI/testing/sysfs-ata
@@ -59,17 +59,18 @@ class
 
 dma_mode
 
-	Transfer modes supported by the device when in DMA mode.
+	DMA transfer mode used by the device.
 	Mostly used by PATA device.
 
 pio_mode
 
-	Transfer modes supported by the device when in PIO mode.
+	PIO transfer mode used by the device.
 	Mostly used by PATA device.
 
 xfer_mode
 
 	Current transfer mode.
+	Mostly used by PATA device.
 
 id
 
--- a/drivers/ata/libata-transport.c
+++ b/drivers/ata/libata-transport.c
@@ -196,7 +196,7 @@ static struct {
 	{ XFER_PIO_0,			"XFER_PIO_0" },
 	{ XFER_PIO_SLOW,		"XFER_PIO_SLOW" }
 };
-ata_bitfield_name_match(xfer,ata_xfer_names)
+ata_bitfield_name_search(xfer, ata_xfer_names)
 
 /*
  * ATA Port attributes