Currently for libata the SCSI device (sdev) associated with an ata_device
is allocated when the port probe has completed.

It's useful to have the SCSI device and its associated request queue
available earlier for the port probe. Specifically if we have the
request queue available, then we can:
- Easily put ATA qc in SCSI cmnd priv data
- Send ATA internal commands on SCSI device request queue for [0]. The
  current solution there is to use the shost sdev request queue, which
  isn't great.
  
This series changes the ata port probe to alloc the sdev in the
ata_device revalidation, and then just do a SCSI starget scan afterwards.

Why an RFC?
1. IPR  driver needs to be fixed up - it does not use ATA EH port probe
   Mail [1] needs following up
2. SATA PMP support needs verification, but I don't have a setup
3. This series needs to be merged into or go after [0]

Patch 1/6 could be merged now.

[0] https://lore.kernel.org/linux-ide/1654770559-101375-1-git-send-email-john.garry@huawei.com/
[1] https://lore.kernel.org/linux-ide/369448ed-f89a-c2db-1850-91450d8b5998@opensource.wdc.com/

Any comments welcome - please have a look.

Based on v6.0-rc4 and tested for QEMU AHCI and libsas.

John Garry (6):
  scsi: core: Use SCSI_SCAN_RESCAN in  __scsi_add_device()
  scsi: scsi_transport_sas: Allocate end device target id in the rphy
    alloc
  scsi: core: Add scsi_get_dev()
  ata: libata-scsi: Add ata_scsi_setup_sdev()
  scsi: libsas: Add sas_ata_setup_device()
  ata: libata-scsi: Allocate sdev early in port probe

 drivers/ata/libata-eh.c           |  4 +++
 drivers/ata/libata-scsi.c         | 45 +++++++++++++++++++++----------
 drivers/ata/libata.h              |  1 +
 drivers/scsi/libsas/sas_ata.c     | 20 ++++++++++++++
 drivers/scsi/scsi_scan.c          | 28 ++++++++++++++++++-
 drivers/scsi/scsi_transport_sas.c | 25 +++++++++++------
 include/linux/libata.h            |  2 ++
 include/scsi/scsi_host.h          |  3 +++
 8 files changed, 105 insertions(+), 23 deletions(-)

-- 
2.35.3

On 9/20/22 19:27, John Garry wrote:
> Currently for libata the SCSI device (sdev) associated with an ata_device
> is allocated when the port probe has completed.
> 
> It's useful to have the SCSI device and its associated request queue
> available earlier for the port probe. Specifically if we have the
> request queue available, then we can:
> - Easily put ATA qc in SCSI cmnd priv data
> - Send ATA internal commands on SCSI device request queue for [0]. The
>    current solution there is to use the shost sdev request queue, which
>    isn't great.
>    
> This series changes the ata port probe to alloc the sdev in the
> ata_device revalidation, and then just do a SCSI starget scan afterwards.
> 
> Why an RFC?
> 1. IPR  driver needs to be fixed up - it does not use ATA EH port probe
>     Mail [1] needs following up

Yes. If IPR could be converted to ata error_handler, a lot of code can 
be simplified in libata too.

> 2. SATA PMP support needs verification, but I don't have a setup

Port multiplier behind a sas HBA will be challenging to setup :)
I can try, but I will need to open up one of my servers and hook a small 
PMP box to one of the pm8001 plugs. I may have the cables for that... 
Let me check.

> 3. This series needs to be merged into or go after [0]
> 
> Patch 1/6 could be merged now.
> 
> [0] https://lore.kernel.org/linux-ide/1654770559-101375-1-git-send-email-john.garry@huawei.com/
> [1] https://lore.kernel.org/linux-ide/369448ed-f89a-c2db-1850-91450d8b5998@opensource.wdc.com/
> 
> Any comments welcome - please have a look.
> 
> Based on v6.0-rc4 and tested for QEMU AHCI and libsas.
> 
> John Garry (6):
>    scsi: core: Use SCSI_SCAN_RESCAN in  __scsi_add_device()
>    scsi: scsi_transport_sas: Allocate end device target id in the rphy
>      alloc
>    scsi: core: Add scsi_get_dev()
>    ata: libata-scsi: Add ata_scsi_setup_sdev()
>    scsi: libsas: Add sas_ata_setup_device()
>    ata: libata-scsi: Allocate sdev early in port probe
> 
>   drivers/ata/libata-eh.c           |  4 +++
>   drivers/ata/libata-scsi.c         | 45 +++++++++++++++++++++----------
>   drivers/ata/libata.h              |  1 +
>   drivers/scsi/libsas/sas_ata.c     | 20 ++++++++++++++
>   drivers/scsi/scsi_scan.c          | 28 ++++++++++++++++++-
>   drivers/scsi/scsi_transport_sas.c | 25 +++++++++++------
>   include/linux/libata.h            |  2 ++
>   include/scsi/scsi_host.h          |  3 +++
>   8 files changed, 105 insertions(+), 23 deletions(-)
> 

-- 
Damien Le Moal
Western Digital Research

On 21/09/2022 05:04, Damien Le Moal wrote:
> On 9/20/22 19:27, John Garry wrote:
>> Currently for libata the SCSI device (sdev) associated with an ata_device
>> is allocated when the port probe has completed.
>>
>> It's useful to have the SCSI device and its associated request queue
>> available earlier for the port probe. Specifically if we have the
>> request queue available, then we can:
>> - Easily put ATA qc in SCSI cmnd priv data
>> - Send ATA internal commands on SCSI device request queue for [0]. The
>>    current solution there is to use the shost sdev request queue, which
>>    isn't great.
>> This series changes the ata port probe to alloc the sdev in the
>> ata_device revalidation, and then just do a SCSI starget scan afterwards.
>>
>> Why an RFC?
>> 1. IPR  driver needs to be fixed up - it does not use ATA EH port probe
>>     Mail [1] needs following up
> 
> Yes. If IPR could be converted to ata error_handler, a lot of code can 
> be simplified in libata too.

Hmmm... yeah, it would be good to see progress there.

> 
>> 2. SATA PMP support needs verification, but I don't have a setup
> 
> Port multiplier behind a sas HBA will be challenging to setup :)
> I can try, but I will need to open up one of my servers and hook a small 
> PMP box to one of the pm8001 plugs. I may have the cables for that... 
> Let me check.

I was more thinking of just AHCI with a port multiplier.

As for SAS controllers, I don't think it's something to be concerned 
about. For a start, I know for sure that hisi_sas HW does not support 
port multipliers, and I don't think that pm8001 does either. In 
addition, libsas does not even support it - I did see a series in the 
scsi list from years ago (to support it), but it did not progress.

Thanks,
John

On 9/21/22 17:24, John Garry wrote:
> On 21/09/2022 05:04, Damien Le Moal wrote:
>> On 9/20/22 19:27, John Garry wrote:
>>> Currently for libata the SCSI device (sdev) associated with an 
>>> ata_device
>>> is allocated when the port probe has completed.
>>>
>>> It's useful to have the SCSI device and its associated request queue
>>> available earlier for the port probe. Specifically if we have the
>>> request queue available, then we can:
>>> - Easily put ATA qc in SCSI cmnd priv data
>>> - Send ATA internal commands on SCSI device request queue for [0]. The
>>>    current solution there is to use the shost sdev request queue, which
>>>    isn't great.
>>> This series changes the ata port probe to alloc the sdev in the
>>> ata_device revalidation, and then just do a SCSI starget scan 
>>> afterwards.
>>>
>>> Why an RFC?
>>> 1. IPR  driver needs to be fixed up - it does not use ATA EH port probe
>>>     Mail [1] needs following up
>>
>> Yes. If IPR could be converted to ata error_handler, a lot of code can 
>> be simplified in libata too.
> 
> Hmmm... yeah, it would be good to see progress there.
> 
>>
>>> 2. SATA PMP support needs verification, but I don't have a setup
>>
>> Port multiplier behind a sas HBA will be challenging to setup :)
>> I can try, but I will need to open up one of my servers and hook a 
>> small PMP box to one of the pm8001 plugs. I may have the cables for 
>> that... Let me check.
> 
> I was more thinking of just AHCI with a port multiplier.

OK. I got confused :)
Easy then, my test box is all hooked up already.
Will give this a spin.

> 
> As for SAS controllers, I don't think it's something to be concerned 
> about. For a start, I know for sure that hisi_sas HW does not support 
> port multipliers, and I don't think that pm8001 does either. In 
> addition, libsas does not even support it - I did see a series in the 
> scsi list from years ago (to support it), but it did not progress.
> 
> Thanks,
> John

-- 
Damien Le Moal
Western Digital Research