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Subject[PATCH 7/8] Input: elantech - detect new ICs and setup Host Notify for them
Date
New ICs are using a different scheme for the alternate bus parameter.
Given that they are new and are only using either PS2 only or PS2 + SMBus
Host Notify, we force those new ICs to use the SMBus solution for enhanced
reporting.

This allows the touchpad found on the Lenovo T480s to report 5 fingers
every 8 ms, instead of having a limit of 2 every 8 ms.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
---
drivers/input/mouse/elantech.c | 11 +++++++----
drivers/input/mouse/elantech.h | 15 +++++++++++++++
2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index a61fbddd6b92..29f55e8e07e9 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -1789,11 +1789,11 @@ static int elantech_setup_smbus(struct psmouse *psmouse,

if (elantech_smbus == ELANTECH_SMBUS_NOT_SET) {
/*
- * FIXME:
- * constraint the I2C capable devices by using FW version,
- * board version, or by using DMI matching
+ * New ICs are enabled by default.
+ * Old ICs are up to the user to decide.
*/
- return -ENXIO;
+ if (!ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version))
+ return -ENXIO;
}

psmouse_info(psmouse, "Trying to set up SMBus access\n");
@@ -1814,6 +1814,9 @@ static int elantech_setup_smbus(struct psmouse *psmouse,
static bool elantech_use_host_notify(struct psmouse *psmouse,
struct elantech_device_info *info)
{
+ if (ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version))
+ return true;
+
switch (info->bus) {
case ETP_BUS_PS2_ONLY:
/* expected case */
diff --git a/drivers/input/mouse/elantech.h b/drivers/input/mouse/elantech.h
index f9b1c485e8d9..119727085a60 100644
--- a/drivers/input/mouse/elantech.h
+++ b/drivers/input/mouse/elantech.h
@@ -115,6 +115,21 @@
#define ETP_BUS_PS2_SMB_ALERT 3
#define ETP_BUS_PS2_SMB_HST_NTFY 4

+/*
+ * New ICs are either using SMBus Host Notify or just plain PS2.
+ *
+ * ETP_FW_VERSION_QUERY is:
+ * Byte 1:
+ * - bit 0..3: IC BODY
+ * Byte 2:
+ * - bit 4: HiddenButton
+ * - bit 5: PS2_SMBUS_NOTIFY
+ * - bit 6: PS2CRCCheck
+ */
+#define ETP_NEW_IC_SMBUS_HOST_NOTIFY(fw_version) \
+ ((((fw_version) & 0x0f2000) == 0x0f2000) && \
+ ((fw_version) & 0x0000ff) > 0)
+
/*
* The base position for one finger, v4 hardware
*/
--
2.14.3
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