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https://codeberg.org/libreboot/lbmk.git
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Leah Rowe
2edd583aee
Courtesy of Kat Inskip who ported this board. Headphone output doesn't work at the moment, due to incorrect verb. Intel VBT is also wrong. Both are taken from another board. This will be amended later with the correct verb and VBT. Signed-off-by: Leah Rowe <leah@libreboot.org>
93 lines
3.4 KiB
Diff
93 lines
3.4 KiB
Diff
From bb286d13cb7702e9396deab04023cc58dcc01a15 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 38/48] 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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