On 2/28/2017 6:03 AM, Patel, Mayurkumar wrote:

quoted

quoted

-	/* Save default state */
-	link->aspm_default = link->aspm_enabled;

But, I am finding a problem with this change, if Policy is set to default,
BIOS enables ASPM L1, but pcie_config_aspm_link() disables ASPM L1
due to link->aspm_enabled is different than link->aspm_default while
called from pcie_aspm_init_link_state() during hotplug insertion.

Thanks for testing. I think it means the enable count logic I put below
is not working.

Yes I believe so.

I was trying to figure out when to use saved values vs. the values in
registers by looking at the enable_cnt.

enable_cnt is 0 during boot on my system.

enable_cnt for the root port on my system is set to 1 for "root port" already without saving
any ASPM related settings. 

The enable_cnt should have been non-zero following an insertion following
remove and default and enabled values should have been identical.

pcie_aspm_init_link_state() is called on the "root port" from hotplug routine when I plug in PCIE Endpoint.
And in my case root port "enable_cnt" is already set to 1 because of root port driver probed already. So
link->aspm_default by  default always sets to pdev->aspm_default which is 0 as it was never set to
BIOS values before. I will continue dig in further to see how the "root port" probe gets triggered
and why it does not call pcie_aspm_init_link_state() to store aspm policy before "enable_cnt" becomes 1 for it.

Can you print out the values of pdev->aspm_default, link->aspm_default,
and link->aspm_enabled in this function along with atomic_read(&pdev->enable_cnt)?

quoted

Yes. Also printed link control register(lnkctl) set by BIOS for upstream port and downstream port
Which gets disabled afterwards due to the link->aspm_default is 0. The prints are in pcie_aspm_cap_init()
Function.

[  199.287732] pci 0000:03:00.0: reg 0x10: [mem 0x00000000-0x00000fff 64bit]
[  199.287748] pci 0000:03:00.0: reg 0x18: [mem 0x00000000-0x000000ff 64bit]
[  199.287864] pci 0000:03:00.0: PME# supported from D0 D3hot D3cold
[  199.288000] pci 0000:03:00.0: System wakeup disabled by ACPI
[  199.299868] upreg lnkcap 00000003 lnkctl=00000042
[  199.299996] dwreg lnkcap  00000002 lnkctl=00000142
[  199.300076] pdev_aspm_default: 0x00000000 link_aspm_default: 0x00000000 aspm_enabled: 0x00000004 enable_cnt: 0x00000001 
[  199.300402] pci 0000:03:00.0: BAR 0: assigned [mem 0xaa000000-0xaa000fff 64bit]
[  199.300413] pci 0000:03:00.0: BAR 2: assigned [mem 0xaa001000-0xaa0010ff 64bit]

quoted

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+	/*
+	 * Save default state from FW when enabling ASPM for the first time
+	 * during boot by looking at the calculated link->aspm_enabled bits
+	 * above and enable_cnt will be zero.
+	 *
+	 * If this path is getting called for the second/third time
+	 * (enable_cnt will be non-zero). Assume that the current state of the
+	 * ASPM registers may not necessarily match what FW asked us to do as
+	 * in the case of hotplug insertion/removal.
+	 */
+	if (!atomic_read(&pdev->enable_cnt))
+		pdev->aspm_default = link->aspm_default = link->aspm_enabled;
+	else
+		link->aspm_default = pdev->aspm_default;

--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

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