Re: [RFC PATCH 6/8] ACPI: use platform bus as the default bus for _HID enumeration
From: Rafael J. Wysocki
Date: Mon Mar 03 2014 - 19:35:19 EST
On 3/4/2014 1:27 AM, Zhang, Rui wrote:
-----Original Message-----
From: Rafael J. Wysocki [mailto:rjw@xxxxxxxxxxxxx]
Sent: Tuesday, March 04, 2014 7:23 AM
To: Zhang, Rui
Cc: linux-acpi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
bhelgaas@xxxxxxxxxx; matthew.garrett@xxxxxxxxxx; Wysocki, Rafael J;
dmitry.torokhov@xxxxxxxxx
Subject: Re: [RFC PATCH 6/8] ACPI: use platform bus as the default bus
for _HID enumeration
Importance: High
On Monday, March 03, 2014 10:11:48 PM Zhang Rui wrote:
On Mon, 2014-03-03 at 00:51 +0100, Rafael J. Wysocki wrote:
On Wednesday, February 26, 2014 05:11:12 PM Zhang Rui wrote:
Because of the growing demand for enumerating ACPI devices to
platform bus, this patch changes the code to enumerate ACPI
devices with _HID/_CID to platform bus by default, unless the
device already has a scan handler attached.
Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
---
drivers/acpi/acpi_platform.c | 28 ----------------------------
drivers/acpi/scan.c | 12 ++++++------
2 files changed, 6 insertions(+), 34 deletions(-)
diff --git a/drivers/acpi/acpi_platform.c
b/drivers/acpi/acpi_platform.c index dbfe49e..33376a9 100644
--- a/drivers/acpi/acpi_platform.c
+++ b/drivers/acpi/acpi_platform.c
@@ -22,24 +22,6 @@
ACPI_MODULE_NAME("platform");
-/*
- * The following ACPI IDs are known to be suitable for
representing as
- * platform devices.
- */
-static const struct acpi_device_id acpi_platform_device_ids[] =
{
-
- { "PNP0D40" },
- { "ACPI0003" },
- { "VPC2004" },
- { "BCM4752" },
-
- /* Intel Smart Sound Technology */
- { "INT33C8" },
- { "80860F28" },
-
- { }
-};
-
/**
* acpi_create_platform_device - Create platform device for ACPI
device node
* @adev: ACPI device node to create a platform device for.
@@ -125,13 +107,3 @@ int acpi_create_platform_device(struct
acpi_device *adev,
kfree(resources);
return 1;
}
-
-static struct acpi_scan_handler platform_handler = {
- .ids = acpi_platform_device_ids,
- .attach = acpi_create_platform_device,
-};
-
-void __init acpi_platform_init(void) -{
- acpi_scan_add_handler(&platform_handler);
-}
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index
5967338..61af32e 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2022,14 +2022,15 @@ static int
acpi_scan_attach_handler(struct acpi_device *device)
handler = acpi_scan_match_handler(hwid->id, &devid);
if (handler) {
ret = handler->attach(device, devid);
- if (ret > 0) {
+ if (ret > 0)
device->handler = handler;
- break;
- } else if (ret < 0) {
- break;
- }
+ if (ret)
+ goto end;
}
}
+end:
+ if (!list_empty(&device->pnp.ids) && !device->handler)
I'm a bit concerned that this check will create platform devices
for
too many ACPI device objects.
agreed. there are some devices created unexpected by this patch, e.g.
on my test machine, I can see
/sys/bus/platform/devices/LNXSYSTM:00 (ACPI system bus/root node)
/sys/bus/platform/devices/PNP0000:00 (PIC)
/sys/bus/platform/devices/PNP0100:00 (system timer?)
Shouldn't we require that _HID or at least _CID is present for
that?
I do not think so.
only devices that invoke acpi_add_ids() may have pnp.ids but no
_HID/_CID, right?
I did a check in the code, those devices include:
Well, I did that too.
ACPI root node
ACPI video
ACPI bay
ACPI dock
IBM SMBus
ACPI Power resource
ACPI processor
ACPI thermal
ACPI fixed power/sleep button
IMO, only the ACPI root node, ACPI power resource, possibly ACPI
processor are the ones that we do not want to see in platform bus.
No, we don't want any of them. So pretty much as I said, only if
_HID/_CID is present, please?
Why? We will convert the drivers for most of those devices from ACPI bus to platform bus sooner or later.
We need to see them in platform bus...
No, we don't.
I'm not sure about IBM SMBus to be honest, but as for the rest:
Why would we want one for the ACPI root?
And for video? Those things are PCI usually devices anyway and we just
add "artificial" HIDs for them.
ACPI docks and bays are handled by the dock driver which creates
platform devices for them already if needed and we don't want duplicates
there.
ACPI processor has its own scan handler that binds those objects to
system devices.
Power resources - no need.
Do we need platform devices for ACPI thermal zones?
Yes, we will need them for fixed buttons, but that's a special case anyway.
Thanks,
Rafael
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