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

[Sergey Shtylyov <s.shtylyov@omp.ru>]

Hello!

On 6/6/22 5:42 AM, Damien Le Moal wrote:

>> The {dma|pio|xfer}_mode sysfs files are incorrectly 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
> 
> Looks good, but Documentation/ABI/testing/sysfs-ata says:

   Completely forgot that the sysfs files are documented as ABIs... :-(
   Hm, shouldn't that file be added to the libata's entry in MAINTAINERS?

> pio_mode:       (RO) Transfer modes supported by the device when
>                 in PIO mode. Mostly used by PATA device.
> 
> xfer_mode:      (RO) Current transfer mode
> 
> dma_mode:       (RO) Transfer modes supported by the device when
>                 in DMA mode. Mostly used by PATA device.
> 
> which seems incorrect/badly worded for pio_mode and dma_mode. Since these
> 2 sysfs attributes do not actually device the pio mask (list of supported

   Device?

> pio modes) but the pio mode that will be used for that device, we should
> reword, no ?

   Yes, of course. :-)

> What about:
> 
> pio_mode:       (RO) Transfer mode used by the device when
>                 in PIO mode. Mostly used by PATA device.
> 
> xfer_mode:      (RO) Current transfer mode
> 
> dma_mode:       (RO) Transfer mode used by the device when
>                 in DMA mode. Mostly used by PATA device.

   Sounds quite tautological... :-)
   What about:

{dma|pio}_mode: (RO) {DMA|PIO} transfer mode used by the device.
                Mostly used by PATA devices.

   I think this should be done in the same patch. Or would you prefer 2 patches?

[...]

MBR, Sergey