Merge pull request 'config/coreboot/default: Disable Latitude early thermal shutdown' (#376) from nic3-14159/lbmk:mec5035-updates into master

Reviewed-on: https://codeberg.org/libreboot/lbmk/pulls/376

2 files changed, 128 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..1b6ed2d3
--- /dev/null
+++ b/config/coreboot/default/patches/0042-ec-dell-mec5035-Add-command-to-disable-EC-initiated-.patch
@@ -0,0 +1,92 @@
+From 4968635d22dcd4f1eed0083565c423f7a42fc74c 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 42/43] 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 dffbb7960c..6c19d1f509 100644
+--- a/src/ec/dell/mec5035/mec5035.c
++++ b/src/ec/dell/mec5035/mec5035.c
+@@ -94,6 +94,25 @@ void mec5035_control_radio(enum ec_radio_dev dev, enum ec_radio_state state)
+ 	ec_command(CMD_RADIO_CTRL);
+ }
+ 
++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 32f791cb01..e2000c455b 100644
+--- a/src/ec/dell/mec5035/mec5035.h
++++ b/src/ec/dell/mec5035/mec5035.h
+@@ -10,6 +10,7 @@
+ enum mec5035_cmd {
+ 	CMD_MOUSE_TP = 0x1a,
+ 	CMD_RADIO_CTRL = 0x2b,
++	CMD_BF = 0xbf,
+ 	CMD_CPU_OK = 0xc2,
+ };
+ 
+@@ -37,5 +38,6 @@ u8 mec5035_mouse_touchpad(enum ec_mouse_setting setting);
+ void mec5035_cpu_ok(void);
+ void mec5035_early_init(void);
+ void mec5035_control_radio(enum ec_radio_dev device, enum ec_radio_state state);
++void mec5035_cmd_bf(u8 i);
+ 
+ #endif /* _EC_DELL_MEC5035_H_ */
+-- 
+2.51.2
+
diff --git a/config/coreboot/default/patches/0043-mb-dell-snb_ivb_latitude-Disable-EC-initiated-shutdo.patch b/config/coreboot/default/patches/0043-mb-dell-snb_ivb_latitude-Disable-EC-initiated-shutdo.patch
new file mode 100644
index 00000000..7c9afc14
--- /dev/null
+++ b/config/coreboot/default/patches/0043-mb-dell-snb_ivb_latitude-Disable-EC-initiated-shutdo.patch
@@ -0,0 +1,36 @@
+From 6e52d15cd47c849567bfc2cb75ccf3c6513dc688 Mon Sep 17 00:00:00 2001
+From: Nicholas Chin <nic.c3.14@gmail.com>
+Date: Sun, 11 May 2025 16:28:23 -0600
+Subject: [PATCH 43/43] mb/dell/snb_ivb_latitude: Disable EC initiated shutdown
+ at 87 degrees
+
+If command 0xBF isn't sent, the EC will shut down the system without
+warning once the CPU reaches approximately 87 degrees, without the
+system thermal throttling first. Call the newly added function from the
+MEC5035 code to send this command and disable this behavior.
+
+Tested on the Latitude E6430.
+
+Change-Id: I2b2dc1e3ab115e05d05eaac06892343394d37fdf
+Signed-off-by: Nicholas Chin <nic.c3.14@gmail.com>
+---
+ src/mainboard/dell/snb_ivb_latitude/early_init.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/src/mainboard/dell/snb_ivb_latitude/early_init.c b/src/mainboard/dell/snb_ivb_latitude/early_init.c
+index ff83db095b..ef385a0a70 100644
+--- a/src/mainboard/dell/snb_ivb_latitude/early_init.c
++++ b/src/mainboard/dell/snb_ivb_latitude/early_init.c
+@@ -11,4 +11,9 @@ void bootblock_mainboard_early_init(void)
+ 			| KBC_LPC_EN | FDD_LPC_EN | LPT_LPC_EN
+ 			| COMB_LPC_EN | COMA_LPC_EN);
+ 	mec5035_early_init();
++
++	/* Observed from LPC logs with vendor firmware. Seems to disable
++	 * EC-initiated shutdown when the CPU reaches approximately 87 degrees.
++	 * The exact meaning of the parameter is currently unknown. */
++	mec5035_cmd_bf(0x07);
+ }
+-- 
+2.51.2
+