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ec/google/chromeec: Optimize battery string readout with caching

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This commit refactors the long battery string implementation to include
caching of the EC response for battery information (model, serial, and
manufacturer).

This optimization reduces resume time by approximately 63ms by
minimizing communication overhead between the AP and EC.

BUG=b:366338622
TEST=Verified on google/tivviks_ufs:
    * Long battery string is displayed when
      EC_GOOGLE_CHROMEEC_READ_BATTERY_LONG_STRING is enabled.
    * Short battery string is displayed when
      EC_GOOGLE_CHROMEEC_READ_BATTERY_LONG_STRING=n.

Change-Id: I32ae5b5e618f20335f3d344811a97f1416df529e
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/84354
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Caveh Jalali <caveh@chromium.org>
This commit is contained in:
Subrata Banik 2024-09-13 21:07:49 +05:30
commit fa5e3d9d44
1 changed files with 57 additions and 16 deletions
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75
src/ec/google/chromeec/acpi/battery.asl
View file

@ -60,6 +60,14 @@ Name(BRSS, 0xff)
#else
Name(BRSS, 0x0)
#endif
// Cached battery string response indicator
Name(BRI1, 0)
Name(BRI2, 0)
Name(BRI3, 0)
// Cached battery string response data to save suspend-resume time
Name(BRS1, Buffer(32) {0})
Name(BRS2, Buffer(32) {0})
Name(BRS3, Buffer(32) {0})
// Read extended battery strings from the selected battery.
// Arg0 = string index
//
@ -82,11 +90,27 @@ Name(BRSS, 0x0)
Method(BRSX, 1, Serialized)
{
// It doesn't make sense to read the FIFO support indicator.
if (Arg0 == 0)
if (Arg0 == 0 || Arg0 > 3)
{
Return ("")
}
// Check if response is already cached
If (Arg0 == 1 && BRI1 == 1)
{
Return (BRS1) /* battery model name */
}
If (Arg0 == 2 && BRI2 == 1)
{
Return (BRS2) /* battery serial number */
}
If (Arg0 == 3 && BRI3 == 1)
{
Return (BRS3) /* battery manufacturer's name */
}
If (BRSS == 0xff)
{
// Write 0 to BSRF to read back a support indicator; nonzero and
@ -109,34 +133,51 @@ Method(BRSX, 1, Serialized)
{
If (Arg0 == 1)
{
Return (ToString (Concatenate (BMOD, 0)))
Local0 = ToString (Concatenate (BMOD, 0))
}
ElseIf (Arg0 == 2)
{
Return (ToString (Concatenate (BSER, 0)))
Local0 = ToString (Concatenate (BSER, 0))
}
ElseIf (Arg0 == 3)
{
Return (ToString (Concatenate (BMFG, 0)))
Local0 = ToString (Concatenate (BMFG, 0))
}
Else
}
Else
{
// Select requested parameter to read
BSRF = Arg0
// Read to end of string, or up to a reasonable maximum length. Reads of
// BSRF consume bytes from the FIFO, so take care to read it only once
// per byte of data.
Local0 = ""
Local1 = BSRF
While (Local1 != 0 && SizeOf (Local0) < 32)
{
Return ("")
Local0 = Concatenate (Local0, ToString (Local1))
Local1 = BSRF
}
}
// Select requested parameter to read
BSRF = Arg0
// Read to end of string, or up to a reasonable maximum length. Reads of
// BSRF consume bytes from the FIFO, so take care to read it only once
// per byte of data.
Local0 = ""
Local1 = BSRF
While (Local1 != 0 && SizeOf (Local0) < 32)
// Store the result in the cache
If (Arg0 == 1)
{
Local0 = Concatenate (Local0, ToString (Local1))
Local1 = BSRF
BRS1 = Local0
BRI1 = 1
}
If (Arg0 == 2)
{
BRS2 = Local0
BRI2 = 1
}
If (Arg0 == 3)
{
BRS3 = Local0
BRI3 = 1
}
Return (Local0)