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soc/intel/apollolake: Reduce D3 cold delay for eMMC controller 

eMMC Controller is taking over 100ms to resume during runtime which
results in I/O latency issues on the Apollo Lake system such as Snappy.
The cause is the Linux Kernel setting the firmware reset time to
100 ms by default.

This patch adds _DSM method for eMMC comtroller for specifying the
device readiness durations. Function index 9 returns package of five
integers to set D3 cold delay to zero and ACPI constant Ones for the
elements where overriding the default values is not desired.

BUG=b:35774937
BRANCH=none
TEST=update snappy coreboot and test i/o latency is under 100ms

Signed-off-by: Zhuo-hao Lee <zhuo-hao.lee@intel.com>
Signed-off-by: Sowmya V <v.sowmya@intel.com>
Change-Id: Idcfe4252b20bead15c2e5b9cb000ff797295f06a
Reviewed-on: https://review.coreboot.org/18806
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
This commit is contained in:
Zhuo-hao Lee 2017-03-14 10:27:28 +08:00 committed by Aaron Durbin
parent 6f80ccc357
commit 07f60aa56f
1 changed files with 43 additions and 0 deletions
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43
src/soc/intel/apollolake/acpi/scs.asl
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@ -47,6 +47,49 @@ Scope (\_SB.PCI0) {
Device (SDHA) {
Name (_ADR, 0x001C0000)
Name (_DDN, "Intel(R) eMMC Controller - 80865ACC")
Name (UUID, ToUUID ("E5C937D0-3553-4D7A-9117-EA4D19C3434D"))
/*
* Device Specific Method
* Arg0 - UUID
* Arg1 - Revision
* Arg2 - Function Index
*/
Method (_DSM, 4)
{
If (LEqual (Arg0, ^UUID)) {
/*
* Function 9: Device Readiness Durations
* Returns a package of five integers covering
* various device related delays in PCIe Base Spec.
*/
If (LEqual (Arg2, 9)) {
/*
* Function 9 support for revision 3.
* ECN link for function definitions
* [https://pcisig.com/sites/default/files/
* specification_documents/
* ECN_fw_latency_optimization_final.pdf]
*/
If (LEqual (Arg1, 3)) {
/*
* Integer 0: FW reset time.
* Integer 1: FW data link up time.
* Integer 2: FW functional level reset
* time.
* Integer 3: FW D3 hot to D0 time.
* Integer 4: FW VF enable time.
* set ACPI constant Ones for elements
* where overriding the default value
* is not desired.
*/
Return (Package (5) {0, Ones, Ones,
Ones, Ones})
}
}
}
Return (Buffer() { 0x00 })
}
Method (_PS0, 0, NotSerialized)
{