Bug 5129

Summary:	remove P-state verification after a P-state write in normal path
Product:	ACPI	Reporter:	Venkatesh Pallipadi (venki)
Component:	Power-Processor	Assignee:	Venkatesh Pallipadi (venki)
Status:	CLOSED CODE_FIX
Severity:	normal	CC:	acpi-bugzilla
Priority:	P2
Hardware:	i386
OS:	Linux
Kernel Version:	2.6.13-rc7	Subsystem:
Regression:	---	Bisected commit-id:
Attachments:	Patch to remove P-state get after a P-state set in acpi-cpufreq driver

Description Venkatesh Pallipadi 2005-08-25 15:58:29 UTC

Distribution:
Hardware Environment:
Software Environment:
Problem Description:

acpi-cpufreq driver does a P-state get after a P-state set, in order to verify 
whether set went through successfully. This test is kind of redundant as set 
goes throught most of the times, and the test is also expensive as a get of P-
states can take a lot of time (same as a set operation) as it goes through SMM 
mode. Effectively, we are doubling the P-state latency due to this get 
opertion. 

The attached patch removes that check unless explicitly asked by 
acpi_pstate_strict parameter.

Comment 1 Venkatesh Pallipadi 2005-08-25 15:59:11 UTC

Created attachment 5767 [details]
Patch to remove P-state get after a P-state set in acpi-cpufreq driver

Comment 2 Andrew Morton 2005-08-25 22:07:05 UTC

Please email this one also

Comment 3 Len Brown 2005-08-26 19:20:10 UTC

applied to acpi test tree.

Comment 4 Len Brown 2005-09-09 09:19:30 UTC

Shipped in 2.6.13-git9.
Closing.