SATA hotplug and notification popup window

[galapogos]

Hi,

I'm developing a SATA storage device, and I'm hot-plugging it in
Mandriva Linux 2008.1 for testing on a Dell Vostro 420 system(P45
chipset, ICH10 in AHCI mode). Sometimes I get a popup window informing
me of the detected drive, but sometimes I don't. I've also noticed
from my probing, that when I do get the window, the SATA reset is
applied immediately upon hot-plug(or at least very soon after).
However, when I don't get that window, the device is reset only a few
seconds later. If I do a fdisk on the drive before the reset, it will
pause until the reset is applied before returning the IDENTIFY
information.

My question is, what determines the behavior of the SATA device upon
hot-plug? Is it the OS, controller, device? Why does it sometimes give
the windows notification and sometimes doesn't? Does the sequence of
cable connection(power first, then data or the opposite, or at the
same time?) matter?

The behavior of my device is dependent on the reset signal being
applied ASAP, so if there's a delay, it would affect the device.

Would appreciate any insights...Thanks!

 

[Grant]

....

The behavior of my device is dependent on the reset signal being
applied ASAP, so if there's a delay, it would affect the device.

What, no power on reset to hold the device until the link is sane?

Grant.

 

[Arno Wagner]

Hi,

I'm developing a SATA storage device, and I'm hot-plugging it in
Mandriva Linux 2008.1 for testing on a Dell Vostro 420 system(P45
chipset, ICH10 in AHCI mode). Sometimes I get a popup window informing
me of the detected drive, but sometimes I don't. I've also noticed
from my probing, that when I do get the window, the SATA reset is
applied immediately upon hot-plug(or at least very soon after).
However, when I don't get that window, the device is reset only a few
seconds later. If I do a fdisk on the drive before the reset, it will
pause until the reset is applied before returning the IDENTIFY
information.

My question is, what determines the behavior of the SATA device upon
hot-plug? Is it the OS, controller, device? Why does it sometimes give
the windows notification and sometimes doesn't? Does the sequence of
cable connection(power first, then data or the opposite, or at the
same time?) matter?

The behavior of my device is dependent on the reset signal being
applied ASAP, so if there's a delay, it would affect the device.

Would appreciate any insights...Thanks!

First, every Linux distro is different. That said, hotplugging
is typically handled by the hotplug script system. Here is
what I suspect is happening: The pop-up is actually a different
mechanism, that under some condifions finds out that a device
has been plugged in. It may be polling or may listen to some
les-tnan-reliable signalling mechanism. If it detects the
hot-plug, then it also forces a reset. If not, then the slower
hotplug scripts eventually notice the device and do their reset.

This is pure conjecture, but if I am right, you should identify
what software is doing pop-up. Maybe doing a mouse-over while
xev (x-event-tracke) is running in an xterm can help. SHould
at least give you a starting point.

You shouls also know that not all SATA controllers support
hot-plugging. For many yyou need cold-plugging, i.e. you
need to run rescan-scsi-bus.sh (or the like) after plugging
the device in for it to be found by the kernel.

Arno