[PATCH v6 2/7] Input: synaptics-rmi4 - handle duplicate/unknown PDT entries

[David Heidelberg via B4 Relay <devnull+david.ixit.cz@kernel.org>]

From: Casey Connolly <casey.connolly@linaro.org>

Some third party rmi4-compatible ICs don't expose their PDT entries
very well. Add a few checks to skip duplicate entries as well as entries
for unsupported functions.

This is required to support some phones with third party displays.

Validated on a stock OnePlus 6T (original parts):
manufacturer: Synaptics, product: S3706B, fw id: 2852315

Co-developed-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Casey Connolly <casey.connolly@linaro.org>
Co-developed-by: David Heidelberg <david@ixit.cz>
Signed-off-by: David Heidelberg <david@ixit.cz>
---
 drivers/input/rmi4/rmi_driver.c | 42 +++++++++++++++++++++++++++++++++++------
 drivers/input/rmi4/rmi_driver.h |  8 ++++++++
 2 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
index ccd9338a44dbe..c7d2f68e65487 100644
--- a/drivers/input/rmi4/rmi_driver.c
+++ b/drivers/input/rmi4/rmi_driver.c
@@ -494,12 +494,39 @@ static void rmi_driver_copy_pdt_to_fd(const struct pdt_entry *pdt,
 	fd->function_version = pdt->function_version;
 }
 
+static bool rmi_pdt_entry_is_valid(struct rmi_device *rmi_dev,
+				   struct pdt_scan_state *state, u8 fn)
+{
+	switch (fn) {
+	case 0x01:
+	case 0x03:
+	case 0x11:
+	case 0x12:
+	case 0x30:
+	case 0x34:
+	case 0x3a:
+	case 0x54:
+	case 0x55:
+		if (state->pdts[fn] == true)
+			return false;
+		break;
+	default:
+		rmi_dbg(RMI_DEBUG_CORE, &rmi_dev->dev,
+			"PDT has unknown function number %#02x\n", fn);
+		return false;
+	}
+
+	state->pdts[fn] = true;
+	state->pdt_count++;
+	return true;
+}
+
 #define RMI_SCAN_CONTINUE	0
 #define RMI_SCAN_DONE		1
 
 static int rmi_scan_pdt_page(struct rmi_device *rmi_dev,
 			     int page,
-			     int *empty_pages,
+			     struct pdt_scan_state *state,
 			     void *ctx,
 			     int (*callback)(struct rmi_device *rmi_dev,
 					     void *ctx,
@@ -522,6 +549,9 @@ static int rmi_scan_pdt_page(struct rmi_device *rmi_dev,
 		if (RMI4_END_OF_PDT(pdt_entry.function_number))
 			break;
 
+		if (!rmi_pdt_entry_is_valid(rmi_dev, state, pdt_entry.function_number))
+			continue;
+
 		retval = callback(rmi_dev, ctx, &pdt_entry);
 		if (retval != RMI_SCAN_CONTINUE)
 			return retval;
@@ -532,11 +562,11 @@ static int rmi_scan_pdt_page(struct rmi_device *rmi_dev,
 	 * or more is found, stop scanning.
 	 */
 	if (addr == pdt_start)
-		++*empty_pages;
+		++state->empty_pages;
 	else
-		*empty_pages = 0;
+		state->empty_pages = 0;
 
-	return (data->bootloader_mode || *empty_pages >= 2) ?
+	return (data->bootloader_mode || state->empty_pages >= 2) ?
 					RMI_SCAN_DONE : RMI_SCAN_CONTINUE;
 }
 
@@ -545,11 +575,11 @@ int rmi_scan_pdt(struct rmi_device *rmi_dev, void *ctx,
 		 void *ctx, const struct pdt_entry *entry))
 {
 	int page;
-	int empty_pages = 0;
+	struct pdt_scan_state state = {0, 0, {0}};
 	int retval = RMI_SCAN_DONE;
 
 	for (page = 0; page <= RMI4_MAX_PAGE; page++) {
-		retval = rmi_scan_pdt_page(rmi_dev, page, &empty_pages,
+		retval = rmi_scan_pdt_page(rmi_dev, page, &state,
 					   ctx, callback);
 		if (retval != RMI_SCAN_CONTINUE)
 			break;
diff --git a/drivers/input/rmi4/rmi_driver.h b/drivers/input/rmi4/rmi_driver.h
index e84495caab151..a4ae2af93ce3a 100644
--- a/drivers/input/rmi4/rmi_driver.h
+++ b/drivers/input/rmi4/rmi_driver.h
@@ -46,6 +46,14 @@ struct pdt_entry {
 	u8 function_number;
 };
 
+#define RMI_PDT_MAX 0x55
+
+struct pdt_scan_state {
+	u8 empty_pages;
+	u8 pdt_count;
+	bool pdts[RMI_PDT_MAX];
+};
+
 #define RMI_REG_DESC_PRESENSE_BITS	(32 * BITS_PER_BYTE)
 #define RMI_REG_DESC_SUBPACKET_BITS	(37 * BITS_PER_BYTE)
 

-- 
2.51.0