diff options
Diffstat (limited to 'config/coreboot/default/patches/0042-ec-dell-mec5035-Add-command-to-disable-EC-initiated-.patch')
| -rw-r--r-- | config/coreboot/default/patches/0042-ec-dell-mec5035-Add-command-to-disable-EC-initiated-.patch | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/config/coreboot/default/patches/0042-ec-dell-mec5035-Add-command-to-disable-EC-initiated-.patch b/config/coreboot/default/patches/0042-ec-dell-mec5035-Add-command-to-disable-EC-initiated-.patch new file mode 100644 index 00000000..b4ebd870 --- /dev/null +++ b/config/coreboot/default/patches/0042-ec-dell-mec5035-Add-command-to-disable-EC-initiated-.patch @@ -0,0 +1,92 @@ +From 732819a85ea6cca637350192fbab9d459dc68439 Mon Sep 17 00:00:00 2001 +From: Nicholas Chin <nic.c3.14@gmail.com> +Date: Sun, 11 May 2025 15:41:22 -0600 +Subject: [PATCH 1/2] ec/dell/mec5035: Add command to disable EC-initiated + thermal shutdown + +If command 0xBF isn't sent, the EC shuts down the system without warning +as soon as the CPU temperature reaches about 87 degrees, without letting +the CPU thermal throttle to try and reduce the temperature. With vendor +firmware, the CPU is able to reach around 100 degrees before thermal +throttling. + +This command was found by collecting EC commands by logging the LPC bus +while running with vendor firmware and then replaying observed commands +from coreboot. By systematically replaying subsets of commands in a +binary search pattern and then stress testing the system, the command to +disable the shutdown was isolated. + +The exact meaning of the parameters for this command are unknown at this +time, but do seem to differ between different generations of these +laptops. Due to this, the commmand should be called by mainboard +specific code which passes the specific parameter value used. + +The Google Wilco EC code, which runs on Latitude Chromebooks and shares +many commands with the standard Latitude ECs, suggests that command 0xBF +tells the EC about the processors CPUID. However, the values observed in +LPC bus logs do not seem to correspond with any CPUID values on the +non-Chromebook systems I tested. + +Observed command parameter values (sent on mailbox registers 2-4): +- E6430 (Ivy Bridge): 0x07, 0x00, 0x00 +- M6800 (Haswell): 0x14, 0x00, 0x00 + +Change-Id: I42f09a3ef681007f64d9c5b1a29248b594737a86 +Signed-off-by: Nicholas Chin <nic.c3.14@gmail.com> +--- + src/ec/dell/mec5035/mec5035.c | 19 +++++++++++++++++++ + src/ec/dell/mec5035/mec5035.h | 2 ++ + 2 files changed, 21 insertions(+) + +diff --git a/src/ec/dell/mec5035/mec5035.c b/src/ec/dell/mec5035/mec5035.c +index bdae929a27..b3574611a7 100644 +--- a/src/ec/dell/mec5035/mec5035.c ++++ b/src/ec/dell/mec5035/mec5035.c +@@ -115,6 +115,25 @@ void mec5035_sleep_enable(void) + ec_command(CMD_SLEEP_ENABLE); + } + ++void mec5035_cmd_bf(u8 i) ++{ ++ /* ++ * If this command isn't sent, the EC shuts down the system as soon as ++ * the CPU temperature reaches about 87 degrees. It is unknown exactly ++ * what the parameters represent. The Google Wilco EC code, which runs ++ * on Latitude Chromebooks and shares some commands with the standard ++ * Latitude EC code, suggests command 0xBF tells the EC the CPUID, but ++ * the values observed in LPC bus logs don't seem to match any CPUID ++ * values of the normal Latitudes this was tested with. ++ * Observed i values: ++ * - E6430 (Ivy Bridge): 0x7 ++ * - M6800 (Haswell): 0x14 ++ */ ++ u8 buf[3] = {i, 0, 0}; ++ write_mailbox_regs(buf, 2, 3); ++ ec_command(CMD_BF); ++} ++ + void mec5035_early_init(void) + { + /* If this isn't sent the EC shuts down the system after about 15 +diff --git a/src/ec/dell/mec5035/mec5035.h b/src/ec/dell/mec5035/mec5035.h +index 51422598c4..f1d8c43051 100644 +--- a/src/ec/dell/mec5035/mec5035.h ++++ b/src/ec/dell/mec5035/mec5035.h +@@ -14,6 +14,7 @@ enum mec5035_cmd { + CMD_POWER_BUTTON_TO_HOST = 0x3e, + CMD_ACPI_WAKEUP_CHANGE = 0x4a, + CMD_SLEEP_ENABLE = 0x64, ++ CMD_BF = 0xbf, + CMD_CPU_OK = 0xc2, + }; + +@@ -66,5 +67,6 @@ void mec5035_change_wake(u8 source, enum ec_wake_change change); + void mec5035_sleep_enable(void); + + void mec5035_smi_sleep(int slp_type); ++void mec5035_cmd_bf(u8 i); + + #endif /* _EC_DELL_MEC5035_H_ */ +-- +2.47.3 + |