Commit 9947d6a0 authored Jun 07, 2017 by Kai-Heng Feng Committed by Christoph Hellwig Jun 07, 2017

nvme: relax APST default max latency to 100ms



Christoph Hellwig suggests we should to make APST work out of the box.
Hence relax the the default max latency to make them able to enter
deepest power state on default.

Here are id-ctrl excerpts from two high latency NVMes:

vid     : 0x14a4
ssvid   : 0x1b4b
mn      : CX2-GB1024-Q11 NVMe LITEON 1024GB
ps    3 : mp:0.1000W non-operational enlat:5000 exlat:5000 rrt:3 rrl:3
          rwt:3 rwl:3 idle_power:- active_power:-
ps    4 : mp:0.0100W non-operational enlat:50000 exlat:100000 rrt:4 rrl:4
          rwt:4 rwl:4 idle_power:- active_power:-

vid     : 0x15b7
ssvid   : 0x1b4b
mn      : A400 NVMe SanDisk 512GB
ps    3 : mp:0.0500W non-operational enlat:51000 exlat:10000 rrt:0 rrl:0
          rwt:0 rwl:0 idle_power:- active_power:-
ps    4 : mp:0.0055W non-operational enlat:1000000 exlat:100000 rrt:0 rrl:0
          rwt:0 rwl:0 idle_power:- active_power:-

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

parent da87591b

drivers/nvme/host/core.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -56,7 +56,7 @@ MODULE_PARM_DESC(max_retries, "max number of retries a command may have");
		static int nvme_char_major;
		module_param(nvme_char_major, int, 0);

		static unsigned long default_ps_max_latency_us = 25000;
		static unsigned long default_ps_max_latency_us = 100000;
		module_param(default_ps_max_latency_us, ulong, 0644);
		MODULE_PARM_DESC(default_ps_max_latency_us,
		"max power saving latency for new devices; use PM QOS to change per device");

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