[PATCH AUTOSEL 5.15 09/14] i2c: Force ELAN06FA touchpad I2C bus freq to 100KHz

[PATCH AUTOSEL 5.15 09/14] i2c: Force ELAN06FA touchpad I2C bus freq to 100KHz

[Sasha Levin]

From: Randolph Ha <rha051117@gmail.com>

[ Upstream commit bfd74cd1fbc026f04446e67d6915c7e199c2bffd ]

When a 400KHz freq is used on this model of ELAN touchpad in Linux,
excessive smoothing (similar to when the touchpad's firmware detects
a noisy signal) is sometimes applied. As some devices' (e.g, Lenovo
V15 G4) ACPI tables specify a 400KHz frequency for this device and
some I2C busses (e.g, Designware I2C) default to a 400KHz freq,
force the speed to 100KHz as a workaround.

For future investigation: This problem may be related to the default
HCNT/LCNT values given by some busses' drivers, because they are not
specified in the aforementioned devices' ACPI tables, and because
the device works without issues on Windows at what is expected to be
a 400KHz frequency. The root cause of the issue is not known.

Signed-off-by: Randolph Ha <rha051117@gmail.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i2c/i2c-core-acpi.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
index 6ce05441178a3..8b06f5d4a4c30 100644
--- a/drivers/i2c/i2c-core-acpi.c
+++ b/drivers/i2c/i2c-core-acpi.c
@@ -327,6 +327,25 @@ static const struct acpi_device_id i2c_acpi_force_400khz_device_ids[] = {
 	{}
 };
 
+static const struct acpi_device_id i2c_acpi_force_100khz_device_ids[] = {
+	/*
+	 * When a 400KHz freq is used on this model of ELAN touchpad in Linux,
+	 * excessive smoothing (similar to when the touchpad's firmware detects
+	 * a noisy signal) is sometimes applied. As some devices' (e.g, Lenovo
+	 * V15 G4) ACPI tables specify a 400KHz frequency for this device and
+	 * some I2C busses (e.g, Designware I2C) default to a 400KHz freq,
+	 * force the speed to 100KHz as a workaround.
+	 *
+	 * For future investigation: This problem may be related to the default
+	 * HCNT/LCNT values given by some busses' drivers, because they are not
+	 * specified in the aforementioned devices' ACPI tables, and because
+	 * the device works without issues on Windows at what is expected to be
+	 * a 400KHz frequency. The root cause of the issue is not known.
+	 */
+	{ "ELAN06FA", 0 },
+	{}
+};
+
 static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
 					   void *data, void **return_value)
 {
@@ -348,6 +367,9 @@ static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
 	if (acpi_match_device_ids(adev, i2c_acpi_force_400khz_device_ids) == 0)
 		lookup->force_speed = I2C_MAX_FAST_MODE_FREQ;
 
+	if (acpi_match_device_ids(adev, i2c_acpi_force_100khz_device_ids) == 0)
+		lookup->force_speed = I2C_MAX_STANDARD_MODE_FREQ;
+
 	return AE_OK;
 }
 
-- 
2.39.5

[PATCH AUTOSEL 5.15 10/14] APEI: GHES: Have GHES honor the panic= setting

[Sasha Levin]

From: Borislav Petkov <bp@alien8.de>

[ Upstream commit 5c0e00a391dd0099fe95991bb2f962848d851916 ]

The GHES driver overrides the panic= setting by force-rebooting the
system after a fatal hw error has been reported. The intent being that
such an error would be reported earlier.

However, this is not optimal when a hard-to-debug issue requires long
time to reproduce and when that happens, the box will get rebooted after
30 seconds and thus destroy the whole hw context of when the error
happened.

So rip out the default GHES panic timeout and honor the global one.

In the panic disabled (panic=0) case, the error will still be logged to
dmesg for later inspection and if panic after a hw error is really
required, then that can be controlled the usual way - use panic= on the
cmdline or set it in the kernel .config's CONFIG_PANIC_TIMEOUT.

Reported-by: Feng Tang <feng.tang@linux.alibaba.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Feng Tang <feng.tang@linux.alibaba.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://patch.msgid.link/20250113125224.GFZ4UMiNtWIJvgpveU@fat_crate.local
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/acpi/apei/ghes.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 160606af8b4f5..a6c8514110736 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -155,8 +155,6 @@ static unsigned long ghes_estatus_pool_size_request;
 static struct ghes_estatus_cache *ghes_estatus_caches[GHES_ESTATUS_CACHES_SIZE];
 static atomic_t ghes_estatus_cache_alloced;
 
-static int ghes_panic_timeout __read_mostly = 30;
-
 static void __iomem *ghes_map(u64 pfn, enum fixed_addresses fixmap_idx)
 {
 	phys_addr_t paddr;
@@ -858,14 +856,16 @@ static void __ghes_panic(struct ghes *ghes,
 			 struct acpi_hest_generic_status *estatus,
 			 u64 buf_paddr, enum fixed_addresses fixmap_idx)
 {
+	const char *msg = GHES_PFX "Fatal hardware error";
+
 	__ghes_print_estatus(KERN_EMERG, ghes->generic, estatus);
 
 	ghes_clear_estatus(ghes, estatus, buf_paddr, fixmap_idx);
 
-	/* reboot to log the error! */
 	if (!panic_timeout)
-		panic_timeout = ghes_panic_timeout;
-	panic("Fatal hardware error!");
+		pr_emerg("%s but panic disabled\n", msg);
+
+	panic(msg);
 }
 
 static int ghes_proc(struct ghes *ghes)
-- 
2.39.5