Re: [PATCH] pci/hotplug: work-around for missing _RMV on HP ZBook G2

From: Jarod Wilson <jarod@redhat.com>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-kernel@vger.kernel.org, Len Brown <lenb@kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org
Subject: Re: [PATCH] pci/hotplug: work-around for missing _RMV on HP ZBook G2
Date: Mon, 18 May 2015 10:30:06 -0400	[thread overview]
Message-ID: <5559F76E.5040203@redhat.com> (raw)
In-Reply-To: <20150516144155.GH31666@google.com>

On 5/16/2015 10:41 AM, Bjorn Helgaas wrote:
> [fix Rafael's email address]
>
> On Sat, May 16, 2015 at 09:37:50AM -0500, Bjorn Helgaas wrote:
>> Hi Jarod,
>>
>> On Thu, May 14, 2015 at 03:33:58PM -0400, Jarod Wilson wrote:
>>> The HP ZBook 15 and 17 Mobile Workstations, generation 2, up to and
>>> including at least BIOS revision 01.07, do not have an ACPI _RMV object
>>> associated with their expresscard slots, so acpi-based hotplug-capable
>>> slot detection fails. If we fall back to pcie-based detection, the systems
>>> work just fine, so this uses dmi matching to do that. With luck, a future
>>> BIOS will remedy this (I've let someone at HP know about the problem),
>>> but for now, just use this for all existing versions.
>>>
>>> Note: they *do* have a proper _RMV object for what I believe is their
>>> thunderbolt ports.
>>>
>>> Tested successfully on an HP ZBook 17 G2 and HP ZBook 15 G2.
>>>
>>> CC: Len Brown <lenb@kernel.org>
>>> CC: "Rafael J. Wysocki" <rjw@sisk.pl>
>>> CC: Bjorn Helgaas <bhelgaas@google.com>
>>> CC: linux-acpi@vger.kernel.org
>>> CC: linux-pci@vger.kernel.org
>>> Signed-off-by: Jarod Wilson <jarod@redhat.com>
>>> ---
>>>   drivers/pci/hotplug/pciehp_acpi.c | 33 +++++++++++++++++++++++++++++++++
>>>   1 file changed, 33 insertions(+)
>>>
>>> diff --git a/drivers/pci/hotplug/pciehp_acpi.c b/drivers/pci/hotplug/pciehp_acpi.c
>>> index 93cc926..db38fb5 100644
>>> --- a/drivers/pci/hotplug/pciehp_acpi.c
>>> +++ b/drivers/pci/hotplug/pciehp_acpi.c
>>> @@ -28,6 +28,7 @@
>>>   #include <linux/pci_hotplug.h>
>>>   #include <linux/slab.h>
>>>   #include <linux/module.h>
>>> +#include <linux/dmi.h>
>>>   #include "pciehp.h"
>>>
>>>   #define PCIEHP_DETECT_PCIE	(0)
>>> @@ -109,10 +110,40 @@ static struct pcie_port_service_driver __initdata dummy_driver = {
>>>   	.probe		= dummy_probe,
>>>   };
>>>
>>> +static int __init set_slot_detection_mode_pcie(const struct dmi_system_id *d)
>>> +{
>>> +	info("%s lacks ACPI _RMV object for expresscard\n", d->ident);
>>> +	return 1;
>>> +}
>>> +
>>> +static struct dmi_system_id __initdata missing_acpi_rmv[] = {
>>> +	/* ZBook 17 through at least bios v01.07 */
>>> +	{
>>> +	 .callback = set_slot_detection_mode_pcie,
>>> +	 .ident = "HP ZBook 17 G2 Mobile Workstation",
>>> +	 .matches = {
>>> +		DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
>>> +		DMI_MATCH(DMI_PRODUCT_NAME, "HP ZBook 17 G2"),
>>> +		},
>>> +	},
>>> +	/* ZBook 15 through at least bios v01.07 */
>>> +	{
>>> +	 .callback = set_slot_detection_mode_pcie,
>>> +	 .ident = "HP ZBook 15 G2 Mobile Workstation",
>>> +	 .matches = {
>>> +		DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
>>> +		DMI_MATCH(DMI_PRODUCT_NAME, "HP ZBook 15 G2"),
>>> +		},
>>> +	},
>>> +	{ .ident = NULL }
>>> +};
>>> +
>>>   static int __init select_detection_mode(void)
>>>   {
>>>   	struct dummy_slot *slot, *tmp;
>>>
>>> +	if (dmi_check_system(missing_acpi_rmv))
>>> +		return PCIEHP_DETECT_PCIE;
>>
>> Oh, my goodness.  I forgot how terrible this path is.  Can anyone write a
>> simple explanation of how we choose to use acpiphp or pciehp?  Module
>> parameters?  A dummy driver that looks for duplicate slot numbers?  Looking
>> for _ADR, _EJ0, _RMV?  This is just nuts.
>>
>> I can't really believe that we're doing this correctly.
>>
>> If I understand correctly, the ZBooks don't have _RMV, but we try to use
>> acpiphp anyway, and acpiphp doesn't work?

They do have an _RMV entry for another device, whatever is on 
0000:00:1c.0, which appears to be the thunderbolt port, but I have yet 
to verify that (no thunderbolt devices to play with yet). The 
expresscard slot is 0000:3c:02.0.

>> That sounds more like a problem
>> with our acpiphp/pciehp selection "algorithm" than a BIOS bug.
>>
>> Jarod, can you open a report at http://bugzilla.kernel.org and attach a
>> complete dmesg log, "lspci -vv" output, and an acpidump?  I'm particularly
>> interested in whether the BIOS granted us control over PCIe native hotplug.
>> If it did, I wonder why we would even attempt to use acpiphp.

Done:

https://bugzilla.kernel.org/show_bug.cgi?id=98581

-- 
Jarod Wilson
jarod@redhat.com