Enhancement to the ahci driver

[Anarchos]

I added some documentation, and made the code a bit clearer. Anyway i am not sure of the following points :

• endianness issues and order of the fields in the scontrol struct.
• "0x%04" B_PRIx16 format string.
• "0x%02" B_PRIx8 format string.
• coding style

[Anarchos]

Solving boot failures due to "Port Connect Change" IRQ storm.

[Anarchos]

The ahci_irq_storm.patch is the same as the ahci.patch I added code and specification documentation for the dealing of the "Port Connect Change" IRQ storm. Same uncertainties remain as before (endianness, format string, coding/doc style)

[Anarchos]

I think it could solve #9275, and other tickets related to boot failures with AMD IXP700 sata controller.

[Anarchos]

By waddlesplah advice, i must add that this patch solved my boot problem.

[waddlesplash]

From IRC:

1:12 PM <axeld> One thing that should be resolved is the TODO comments
1:13 PM <axeld> Another thing is that it should be enough to refer to the spec instead of quoting it
1:13 PM <axeld> Excessive comments usually aren't helpful in reading source code
1:14 PM <axeld> Anarchos: Other than that, I would have to actually read the specs to be able to comment more :-)

[waddlesplash]

Cleaned-up Git-patch version of Anarchos' changes.

[pulkomandy]

The order of the fields in a bitfield is implementation defined, I don't think it is a good idea to map them to the hardware this way. This should use some endian-aware solution - we probably have macros borrowed from FreeBSD to manage this somewhere.

I can't comment on the functional changes, since I don't know the ATA spec much.

[axeld]

Applied in hrev49590. Unfortunately, the scontrol structure changed the access to a 32 bit field to 8 bits which broke some HW, and I didn't notice that.

Apart from that, I cleaned it up a little, and added a check for the ST flag in the command register as the specification suggests.

[korli]

@Anarchos may I suggest you post an update to this article you wrote?

​https://www.haiku-os.org/node/6004 ?