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https://codeberg.org/libreboot/lbmk.git
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1068acd2c0
latest coreboot rev as of literally today this is in preparation for a thinkpad x270 port using a WIP patch that was contributed Signed-off-by: Leah Rowe <leah@libreboot.org>
93 lines
3.4 KiB
Diff
93 lines
3.4 KiB
Diff
From 357872d4b9c5fdc559d10596b0f21d7065c8fdc5 Mon Sep 17 00:00:00 2001
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From: Nicholas Chin <nic.c3.14@gmail.com>
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Date: Sun, 11 May 2025 15:41:22 -0600
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Subject: [PATCH 38/45] ec/dell/mec5035: Add command to disable EC-initiated
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thermal shutdown
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If command 0xBF isn't sent, the EC shuts down the system without warning
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as soon as the CPU temperature reaches about 87 degrees, without letting
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the CPU thermal throttle to try and reduce the temperature. With vendor
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firmware, the CPU is able to reach around 100 degrees before thermal
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throttling.
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This command was found by collecting EC commands by logging the LPC bus
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while running with vendor firmware and then replaying observed commands
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from coreboot. By systematically replaying subsets of commands in a
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binary search pattern and then stress testing the system, the command to
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disable the shutdown was isolated.
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The exact meaning of the parameters for this command are unknown at this
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time, but do seem to differ between different generations of these
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laptops. Due to this, the commmand should be called by mainboard
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specific code which passes the specific parameter value used.
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The Google Wilco EC code, which runs on Latitude Chromebooks and shares
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many commands with the standard Latitude ECs, suggests that command 0xBF
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tells the EC about the processors CPUID. However, the values observed in
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LPC bus logs do not seem to correspond with any CPUID values on the
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non-Chromebook systems I tested.
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Observed command parameter values (sent on mailbox registers 2-4):
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- E6430 (Ivy Bridge): 0x07, 0x00, 0x00
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- M6800 (Haswell): 0x14, 0x00, 0x00
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Change-Id: I42f09a3ef681007f64d9c5b1a29248b594737a86
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Signed-off-by: Nicholas Chin <nic.c3.14@gmail.com>
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---
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src/ec/dell/mec5035/mec5035.c | 19 +++++++++++++++++++
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src/ec/dell/mec5035/mec5035.h | 2 ++
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2 files changed, 21 insertions(+)
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diff --git a/src/ec/dell/mec5035/mec5035.c b/src/ec/dell/mec5035/mec5035.c
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index c5067c16f6..b316fa4989 100644
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--- a/src/ec/dell/mec5035/mec5035.c
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+++ b/src/ec/dell/mec5035/mec5035.c
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@@ -114,6 +114,25 @@ void mec5035_sleep_enable(void)
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ec_command(CMD_SLEEP_ENABLE);
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}
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+void mec5035_cmd_bf(u8 i)
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+{
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+ /*
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+ * If this command isn't sent, the EC shuts down the system as soon as
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+ * the CPU temperature reaches about 87 degrees. It is unknown exactly
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+ * what the parameters represent. The Google Wilco EC code, which runs
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+ * on Latitude Chromebooks and shares some commands with the standard
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+ * Latitude EC code, suggests command 0xBF tells the EC the CPUID, but
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+ * the values observed in LPC bus logs don't seem to match any CPUID
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+ * values of the normal Latitudes this was tested with.
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+ * Observed i values:
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+ * - E6430 (Ivy Bridge): 0x7
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+ * - M6800 (Haswell): 0x14
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+ */
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+ u8 buf[3] = {i, 0, 0};
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+ write_mailbox_regs(buf, 2, 3);
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+ ec_command(CMD_BF);
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+}
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+
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void mec5035_early_init(void)
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{
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/* If this isn't sent the EC shuts down the system after about 15
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diff --git a/src/ec/dell/mec5035/mec5035.h b/src/ec/dell/mec5035/mec5035.h
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index 5cd907bf71..71d1a71075 100644
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--- a/src/ec/dell/mec5035/mec5035.h
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+++ b/src/ec/dell/mec5035/mec5035.h
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@@ -14,6 +14,7 @@ enum mec5035_cmd {
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CMD_POWER_BUTTON_TO_HOST = 0x3e,
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CMD_ACPI_WAKEUP_CHANGE = 0x4a,
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CMD_SLEEP_ENABLE = 0x64,
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+ CMD_BF = 0xbf,
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CMD_CPU_OK = 0xc2,
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};
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@@ -65,5 +66,6 @@ void mec5035_change_wake(u8 source, enum ec_wake_change change);
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void mec5035_sleep_enable(void);
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void mec5035_smi_sleep(int slp_type);
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+void mec5035_cmd_bf(u8 i);
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#endif /* _EC_DELL_MEC5035_H_ */
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--
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2.47.3
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