[PATCH] ahci_sunxi: Make AHCI_HFLAG_NO_PMP flag configurable with a module option

[Tejun Heo]

On Fri, Nov 14, 2014 at 04:09:31PM +0100, Hans de Goede wrote:
> The use of the AHCI_HFLAG_NO_PMP flag is something which we inherited from
> the Allwinner android kernel sources, and I've always wanted to test if this
> is really necessary.
> 
> So recently I've bought a sata port multiplexer, and I've given this a test
> spin on both A10 and A20 devices, and it seems to work fine:
> 
> [    2.154456] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
> [    2.161092] ata1.15: Port Multiplier 1.2, 0x197b:0x0325 r0, 5 ports, feat 0x5/0xf
> [    2.175511] ata1.00: hard resetting link
> [    2.524929] ata1.00: SATA link up 3.0 Gbps (SStatus 123 SControl 320)
> [    2.531430] ata1.01: hard resetting link
> [    2.974465] ata1.01: link resume succeeded after 1 retries
> [    3.094932] ata1.01: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
> [    3.101431] ata1.02: hard resetting link
> [    4.174466] ata1.02: failed to resume link (SControl 0)
> [    4.180065] ata1.02: SATA link down (SStatus 0 SControl 0)
> (and the same for links 3 and 4)
> 
> Once the NO_PMP flag is removed it correctly sees the 2 disks which I've
> attached, and I can mount and use them just fine.
> 
> Unfortunately when I then directly attached a disk to the sata port on the
> sunxi SoC, and booted a kernel without the AHCI_HFLAG_NO_PMP flag, it would
> not recognize that disk.
> 
> It turns out that the sata controller in the sunxi SoCs fails to handle
> soft-resets issued to directly attached disks, and when pmp support is
> enabled the kernel will always issue a soft-reset.
> 
> So add a module parameter to enable pmp usage, and default this to off, so
> that directly attached disks keep working normally.
> 
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>

Applied to libata/for-3.19.

Thanks.

-- 
tejun