HID: Intel-thc-hid: Intel-quicki2c: Enhance QuickI2C reset flow

JIRA: https://issues.redhat.com/browse/RHEL-101770
Upstream Status: 6.16-rc
Tested: with the hid-tools test suite and some hardware

commit 73f3a74
Author: Even Xu <even.xu@intel.com>
Date:   Wed May 14 14:26:38 2025 +0800

    HID: Intel-thc-hid: Intel-quicki2c: Enhance QuickI2C reset flow

    During customer board enabling, it was found: some touch devices
    prepared reset response, but either forgot sending interrupt or
    THC missed reset interrupt because of timing issue. THC QuickI2C
    driver depends on interrupt to read reset response, in this case,
    it will cause driver waiting timeout.

    This patch enhances the flow by adding manually reset response
    reading after waiting for reset interrupt timeout.

    Signed-off-by: Even Xu <even.xu@intel.com>
    Tested-by: Chong Han <chong.han@intel.com>
    Fixes: 66b59bf ("HID: intel-thc-hid: intel-quicki2c: Complete THC QuickI2C driver")
    Signed-off-by: Jiri Kosina <jkosina@suse.com>

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Author: bentiss

drivers/hid/intel-thc-hid/intel-quicki2c/quicki2c-protocol.c

@@ -4,6 +4,7 @@
 #include <linux/bitfield.h>
 #include <linux/hid.h>
 #include <linux/hid-over-i2c.h>
+#include <linux/unaligned.h>
 
 #include "intel-thc-dev.h"
 #include "intel-thc-dma.h"
@@ -200,6 +201,9 @@ int quicki2c_set_report(struct quicki2c_device *qcdev, u8 report_type,
 
 int quicki2c_reset(struct quicki2c_device *qcdev)
 {
+	u16 input_reg = le16_to_cpu(qcdev->dev_desc.input_reg);
+	size_t read_len = HIDI2C_LENGTH_LEN;
+	u32 prd_len = read_len;
 	int ret;
 
 	qcdev->reset_ack = false;
@@ -213,12 +217,32 @@ int quicki2c_reset(struct quicki2c_device *qcdev)
 
 	ret = wait_event_interruptible_timeout(qcdev->reset_ack_wq, qcdev->reset_ack,
 					       HIDI2C_RESET_TIMEOUT * HZ);
-	if (ret <= 0 || !qcdev->reset_ack) {
+	if (qcdev->reset_ack)
+		return 0;
+
+	/*
+	 * Manually read reset response if it wasn't received, in case reset interrupt
+	 * was missed by touch device or THC hardware.
+	 */
+	ret = thc_tic_pio_read(qcdev->thc_hw, input_reg, read_len, &prd_len,
+			       (u32 *)qcdev->input_buf);
+	if (ret) {
+		dev_err_once(qcdev->dev, "Read Reset Response failed, ret %d\n", ret);
+		return ret;
+	}
+
+	/*
+	 * Check response packet length, it's first 16 bits of packet.
+	 * If response packet length is zero, it's reset response, otherwise not.
+	 */
+	if (get_unaligned_le16(qcdev->input_buf)) {
 		dev_err_once(qcdev->dev,
 			     "Wait reset response timed out ret:%d timeout:%ds\n",
 			     ret, HIDI2C_RESET_TIMEOUT);
 		return -ETIMEDOUT;
 	}
 
+	qcdev->reset_ack = true;
+
 	return 0;
 }