Re: [PATCH] ata: libata-pmp: disable the SEMB port on Marvell 88SM9705

[Kyrylo Biryuk]

Tested on a Synology DX1222: four 88SM9705 (0x1b4b:0x9705 r160,
6 ports) behind an 88SE9235 that is passed through to a KVM guest,
6 disks. The same 7.4-rc1 tree built with and without the patch,
one boot each:

                                    softreset  reset failed,  last disk
                                    failed     giving up      attached
  7.4-rc1, no libata.force          60         12             197 s
  7.4-rc1, libata.force=N.05:norst   0          0              70 s
  7.4-rc1 + this patch, no force     0          0              11 s

With the patch, each PMP logs one "ataN.05: failed to resume link
(SControl 0)" and port 5 is then left alone. The same disks attach
in all three boots.

Tested-by: Kyrylo Biryuk <illofspeed@xxxxxxxxx>

The test boots were scripted and run by an AI coding assistant on
my hardware; I checked the logs.

Kyrylo Biryuk