[v2] ata: libata-transport: fix {dma|pio|xfer}_mode sysfs files

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 misdocumentation, somewhat reword the {dma|pio}_mode
file doc and add a note about being mostly useful for the 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

---
This patch is against the 'master' branch of Damien's 'libata.git' repo.

Changes in version 2:
- added the Documentation/ABI/testing/sysfs-ata file, updating the patch
  description accordingly.

 Documentation/ABI/testing/sysfs-ata |   11 ++++++-----
 drivers/ata/libata-transport.c      |    2 +-
 2 files changed, 7 insertions(+), 6 deletions(-)

On 6/9/22 04:51, Sergey Shtylyov wrote:
> 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 misdocumentation, somewhat reword the {dma|pio}_mode
> file doc and add a note about being mostly useful for the 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
> 
> ---
> This patch is against the 'master' branch of Damien's 'libata.git' repo.
> 
> Changes in version 2:
> - added the Documentation/ABI/testing/sysfs-ata file, updating the patch
>   description accordingly.
> 
>  Documentation/ABI/testing/sysfs-ata |   11 ++++++-----
>  drivers/ata/libata-transport.c      |    2 +-
>  2 files changed, 7 insertions(+), 6 deletions(-)
> 
> Index: libata/Documentation/ABI/testing/sysfs-ata
> ===================================================================
> --- libata.orig/Documentation/ABI/testing/sysfs-ata
> +++ libata/Documentation/ABI/testing/sysfs-ata
> @@ -107,13 +107,14 @@ Description:
>  				described in ATA8 7.16 and 7.17. Only valid if
>  				the device is not a PM.
>  
> -		pio_mode:	(RO) Transfer modes supported by the device when
> -				in PIO mode. Mostly used by PATA device.
> +		pio_mode:	(RO) PIO transfer mode used by the device.
> +				Mostly used by the PATA devices.

s/by the PATA devices/by PATA devices
(since here we talk about PATA devices in general)
Same fix below. I will fix that up when applying.

>  
> -		xfer_mode:	(RO) Current transfer mode
> +		xfer_mode:	(RO) Current transfer mode. Mostly used by
> +				the PATA devices.
>  
> -		dma_mode:	(RO) Transfer modes supported by the device when
> -				in DMA mode. Mostly used by PATA device.
> +		dma_mode:	(RO) DMA transfer mode used by the device.
> +				Mostly used by the PATA devices.
>  
>  		class:		(RO) Device class. Can be "ata" for disk,
>  				"atapi" for packet device, "pmp" for PM, or
> Index: libata/drivers/ata/libata-transport.c
> ===================================================================
> --- libata.orig/drivers/ata/libata-transport.c
> +++ libata/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

On 6/9/22 04:51, Sergey Shtylyov wrote:
> 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 misdocumentation, somewhat reword the {dma|pio}_mode
> file doc and add a note about being mostly useful for the 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

Applied to for-5.19-fixes with the typo fixed. Thanks !