[PATCH 0/7] Input: synaptics-rmi4: add quirks for third party touchscreen controllers

[PATCH 0/7] Input: synaptics-rmi4: add quirks for third party touchscreen controllers

[Caleb Connolly]

With the growing popularity of running upstream Linux on mobile devices,
we're beginning to run into more and more edgecases. The OnePlus 6 is a
fairly well supported 2018 era smartphone, selling over a million units
in it's first 22 days. With this level of popularity, it's almost
inevitable that we get third party replacement displays, and as a
result, replacement touchscreen controllers.

The OnePlus 6 shipped with an extremely usecase specific touchscreen
driver, it implemented only the bare minimum parts of the highly generic
rmi4 protocol, instead hardcoding most of the register addresses.

As a result, the third party touchscreen controllers that are often
found in replacement screens, implement only the registers that the
downstream driver reads from. They additionally have other restrictions
such as heavy penalties on unaligned reads.

This series attempts to implement the necessary workaround to support
some of these chips with the rmi4 driver. Although it's worth noting
that at the time of writing there are other unofficial controllers in
the wild that don't work even with these patches.

We have been shipping these patches in postmarketOS for the last several
months, and they are known to not cause any regressions on the OnePlus
6/6T (with the official Synaptics controller), however I don't own any
other rmi4 hardware to further validate this.

These patches were contributed by a community developer who has given
permission for me to submit them on their behalf.

---
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Vincent Huang <vincent.huang@tw.synaptics.com>
Cc: methanal <baclofen@tuta.io>
Cc: linux-input@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: phone-devel@vger.kernel.org
Cc: ~postmarketos/upstreaming@lists.sr.ht

---
Caleb Connolly (2):
      dt-bindings: input: syna,rmi4: document syna,pdt-fallback-desc
      Input: synaptics-rmi4 - handle duplicate/unknown PDT entries

methanal (5):
      Input: synaptics-rmi4 - f12: use hardcoded values for aftermarket touch ICs
      Input: synaptics-rmi4 - f55: handle zero electrode count
      Input: synaptics-rmi4 - don't do unaligned reads in IRQ context
      Input: synaptics-rmi4 - read product ID on aftermarket touch ICs
      Input: synaptics-rmi4 - support fallback values for PDT descriptor bytes

 .../devicetree/bindings/input/syna,rmi4.yaml       |  10 ++
 drivers/input/rmi4/rmi_driver.c                    | 134 ++++++++++++++++++---
 drivers/input/rmi4/rmi_driver.h                    |   8 ++
 drivers/input/rmi4/rmi_f01.c                       |  14 +++
 drivers/input/rmi4/rmi_f12.c                       | 117 ++++++++++++++----
 drivers/input/rmi4/rmi_f55.c                       |   5 +
 include/linux/rmi.h                                |   3 +
 7 files changed, 247 insertions(+), 44 deletions(-)
---
base-commit: b0d95ff7653ef6ace66a24d6c09147d0731825ce

// Caleb (they/them)

[PATCH 1/7] dt-bindings: input: syna,rmi4: document syna,pdt-fallback-desc

[Caleb Connolly]

This new property allows devices to specify some register values which
are missing on units with third party replacement displays. These
displays use unofficial touch ICs which only implement a subset of the
RMI4 specification.

Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
---
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
To: Rob Herring <robh+dt@kernel.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
To: Conor Dooley <conor+dt@kernel.org>
Cc: devicetree@vger.kernel.org
---
 Documentation/devicetree/bindings/input/syna,rmi4.yaml | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/syna,rmi4.yaml b/Documentation/devicetree/bindings/input/syna,rmi4.yaml
index 4d4e1a8e36be..bd6beb67ac21 100644
--- a/Documentation/devicetree/bindings/input/syna,rmi4.yaml
+++ b/Documentation/devicetree/bindings/input/syna,rmi4.yaml
@@ -49,6 +49,16 @@ properties:
     description:
       Delay to wait after powering on the device.
 
+  syna,pdt-fallback-desc:
+    $ref: /schemas/types.yaml#/definitions/uint8-array
+    description:
+      An array of pairs of function number and version. These are used
+      on some devices with replacement displays that use unofficial touch
+      controllers. These controllers do report the properties of their PDT
+      entries, but leave the function_number and function_version registers
+      blank. These values should match exactly the 5th and 4th bytes of each
+      PDT entry from the original display's touch controller.
+
   vdd-supply: true
   vio-supply: true
 

-- 
2.42.0

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

[Caleb Connolly]

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: methanal <baclofen@tuta.io>
Signed-off-by: methanal <baclofen@tuta.io>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
---
 drivers/input/rmi4/rmi_driver.c | 47 +++++++++++++++++++++++++++++++++++------
 drivers/input/rmi4/rmi_driver.h |  6 ++++++
 2 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
index 258d5fe3d395..cd3e4e77ab9b 100644
--- a/drivers/input/rmi4/rmi_driver.c
+++ b/drivers/input/rmi4/rmi_driver.c
@@ -493,12 +493,44 @@ 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)
+{
+	int i;
+
+	switch (fn) {
+	case 0x01:
+	case 0x03:
+	case 0x11:
+	case 0x12:
+	case 0x30:
+	case 0x34:
+	case 0x3a:
+	case 0x54:
+	case 0x55:
+		break;
+
+	default:
+		rmi_dbg(RMI_DEBUG_CORE, &rmi_dev->dev,
+			"PDT has unknown function number %#02x\n", fn);
+		return false;
+	}
+
+	for (i = 0; i < state->pdt_count; i++) {
+		if (state->pdts[i] == fn)
+			return false;
+	}
+
+	state->pdts[state->pdt_count++] = fn;
+	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,
@@ -521,6 +553,9 @@ 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;
@@ -531,11 +566,11 @@ 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;
 }
 
@@ -544,11 +579,11 @@ 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 1c6c6086c0e5..e1a5412f2f8f 100644
--- a/drivers/input/rmi4/rmi_driver.h
+++ b/drivers/input/rmi4/rmi_driver.h
@@ -46,6 +46,12 @@ struct pdt_entry {
 	u8 function_number;
 };
 
+struct pdt_scan_state {
+	u8 empty_pages;
+	u8 pdt_count;
+	u8 pdts[254];
+};
+
 #define RMI_REG_DESC_PRESENSE_BITS	(32 * BITS_PER_BYTE)
 #define RMI_REG_DESC_SUBPACKET_BITS	(37 * BITS_PER_BYTE)
 

-- 
2.42.0

[PATCH 3/7] Input: synaptics-rmi4 - f12: use hardcoded values for aftermarket touch ICs

[Caleb Connolly]

From: methanal <baclofen@tuta.io>

Some replacement displays include third-party touch ICs which are
devoid of register descriptors. Create a fake data register descriptor
for such ICs and provide hardcoded default values.

It isn't possible to reliably determine if the touch IC is original or
not, so these fallback values are offered as an alternative to the error
path when register descriptors aren't available.

Signed-off-by: methanal <baclofen@tuta.io>
[changes for readability / codeflow, checkpatch fixes]
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
---
 drivers/input/rmi4/rmi_f12.c | 117 +++++++++++++++++++++++++++++++++----------
 1 file changed, 91 insertions(+), 26 deletions(-)

diff --git a/drivers/input/rmi4/rmi_f12.c b/drivers/input/rmi4/rmi_f12.c
index 7e97944f7616..719ee3b42550 100644
--- a/drivers/input/rmi4/rmi_f12.c
+++ b/drivers/input/rmi4/rmi_f12.c
@@ -195,6 +195,41 @@ static void rmi_f12_process_objects(struct f12_data *f12, u8 *data1, int size)
 		rmi_2d_sensor_abs_report(sensor, &sensor->objs[i], i);
 }
 
+static void rmi_f12_set_hardcoded_desc(struct rmi_function *fn, struct f12_data *f12)
+{
+	struct rmi_2d_sensor *sensor = &f12->sensor;
+	struct rmi_register_desc_item *reg_desc;
+
+	/* We have no f12->data_reg_desc, so the pkt_size is 0, override it with
+	 * a somewhat sensible default (this corresponds to 10 fingers).
+	 */
+	sensor->pkt_size = 88;
+
+	/*
+	 * There are no register descriptors to get these values from.
+	 * We set them to high values to either be overwritten by the clip
+	 * properties from devicetree, or to just not get in the way.
+	 */
+	sensor->max_x = 65535;
+	sensor->max_y = 65535;
+
+	/*
+	 * Create the Data1 register descriptor so that touch events
+	 * can work properly.
+	 */
+	reg_desc = devm_kcalloc(&fn->dev, 1,
+			sizeof(struct rmi_register_desc_item), GFP_KERNEL);
+	reg_desc->reg = 1;
+	reg_desc->reg_size = 80;
+	reg_desc->num_subpackets = 10;
+
+	f12->data1 = reg_desc;
+	f12->data1_offset = 0;
+	sensor->nbr_fingers = reg_desc->num_subpackets;
+	sensor->report_abs = 1;
+	sensor->attn_size += reg_desc->reg_size;
+}
+
 static irqreturn_t rmi_f12_attention(int irq, void *ctx)
 {
 	int retval;
@@ -315,6 +350,40 @@ static int rmi_f12_config(struct rmi_function *fn)
 	return 0;
 }
 
+static int rmi_f12_sensor_init(struct rmi_function *fn, struct f12_data *f12)
+{
+	struct rmi_2d_sensor *sensor = &f12->sensor;
+
+	sensor->fn = fn;
+	f12->data_addr = fn->fd.data_base_addr;
+
+	/* On quirky devices that don't have a data_reg_desc we hardcode the packet
+	 * in rmi_f12_set_hardcoded_desc(). Make sure not to set it to 0 here.
+	 */
+	if (!sensor->pkt_size)
+		sensor->pkt_size = rmi_register_desc_calc_size(&f12->data_reg_desc);
+
+	sensor->axis_align =
+		f12->sensor_pdata.axis_align;
+
+	sensor->x_mm = f12->sensor_pdata.x_mm;
+	sensor->y_mm = f12->sensor_pdata.y_mm;
+	sensor->dribble = f12->sensor_pdata.dribble;
+
+	if (sensor->sensor_type == rmi_sensor_default)
+		sensor->sensor_type =
+			f12->sensor_pdata.sensor_type;
+
+	rmi_dbg(RMI_DEBUG_FN, &fn->dev, "%s: data packet size: %d\n", __func__,
+		sensor->pkt_size);
+
+	sensor->data_pkt = devm_kzalloc(&fn->dev, sensor->pkt_size, GFP_KERNEL);
+	if (!sensor->data_pkt)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static int rmi_f12_probe(struct rmi_function *fn)
 {
 	struct f12_data *f12;
@@ -328,6 +397,7 @@ static int rmi_f12_probe(struct rmi_function *fn)
 	struct rmi_driver_data *drvdata = dev_get_drvdata(&rmi_dev->dev);
 	u16 data_offset = 0;
 	int mask_size;
+	bool hardcoded_desc_quirk = false;
 
 	rmi_dbg(RMI_DEBUG_FN, &fn->dev, "%s\n", __func__);
 
@@ -342,9 +412,9 @@ static int rmi_f12_probe(struct rmi_function *fn)
 	++query_addr;
 
 	if (!(buf & BIT(0))) {
-		dev_err(&fn->dev,
-			"Behavior of F12 without register descriptors is undefined.\n");
-		return -ENODEV;
+		rmi_dbg(RMI_DEBUG_FN, &fn->dev,
+			"No register descriptors defined for F12, using fallback\n");
+		hardcoded_desc_quirk = true;
 	}
 
 	f12 = devm_kzalloc(&fn->dev, sizeof(struct f12_data) + mask_size * 2,
@@ -352,6 +422,8 @@ static int rmi_f12_probe(struct rmi_function *fn)
 	if (!f12)
 		return -ENOMEM;
 
+	dev_set_drvdata(&fn->dev, f12);
+
 	f12->abs_mask = (unsigned long *)((char *)f12
 			+ sizeof(struct f12_data));
 	f12->rel_mask = (unsigned long *)((char *)f12
@@ -370,6 +442,18 @@ static int rmi_f12_probe(struct rmi_function *fn)
 		f12->sensor_pdata = pdata->sensor_pdata;
 	}
 
+	sensor = &f12->sensor;
+
+	if (hardcoded_desc_quirk) {
+		rmi_f12_set_hardcoded_desc(fn, f12);
+
+		ret = rmi_f12_sensor_init(fn, f12);
+		if (ret)
+			return ret;
+
+		goto skip_register_desc;
+	}
+
 	ret = rmi_read_register_desc(rmi_dev, query_addr,
 					&f12->query_reg_desc);
 	if (ret) {
@@ -400,29 +484,9 @@ static int rmi_f12_probe(struct rmi_function *fn)
 	}
 	query_addr += 3;
 
-	sensor = &f12->sensor;
-	sensor->fn = fn;
-	f12->data_addr = fn->fd.data_base_addr;
-	sensor->pkt_size = rmi_register_desc_calc_size(&f12->data_reg_desc);
-
-	sensor->axis_align =
-		f12->sensor_pdata.axis_align;
-
-	sensor->x_mm = f12->sensor_pdata.x_mm;
-	sensor->y_mm = f12->sensor_pdata.y_mm;
-	sensor->dribble = f12->sensor_pdata.dribble;
-
-	if (sensor->sensor_type == rmi_sensor_default)
-		sensor->sensor_type =
-			f12->sensor_pdata.sensor_type;
-
-	rmi_dbg(RMI_DEBUG_FN, &fn->dev, "%s: data packet size: %d\n", __func__,
-		sensor->pkt_size);
-	sensor->data_pkt = devm_kzalloc(&fn->dev, sensor->pkt_size, GFP_KERNEL);
-	if (!sensor->data_pkt)
-		return -ENOMEM;
-
-	dev_set_drvdata(&fn->dev, f12);
+	ret = rmi_f12_sensor_init(fn, f12);
+	if (ret)
+		return ret;
 
 	ret = rmi_f12_read_sensor_tuning(f12);
 	if (ret)
@@ -520,6 +584,7 @@ static int rmi_f12_probe(struct rmi_function *fn)
 		data_offset += item->reg_size;
 	}
 
+skip_register_desc:
 	/* allocate the in-kernel tracking buffers */
 	sensor->tracking_pos = devm_kcalloc(&fn->dev,
 			sensor->nbr_fingers, sizeof(struct input_mt_pos),

-- 
2.42.0

[PATCH 4/7] Input: synaptics-rmi4 - f55: handle zero electrode count

[Caleb Connolly]

From: methanal <baclofen@tuta.io>

Some third party ICs claim to support f55 but report an electrode count
of 0. Catch this and bail out early so that we don't confuse the i2c bus
with 0 sized reads.

Signed-off-by: methanal <baclofen@tuta.io>
[simplify code, adjust wording]
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
---
 drivers/input/rmi4/rmi_f55.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/input/rmi4/rmi_f55.c b/drivers/input/rmi4/rmi_f55.c
index 488adaca4dd0..ad2ef14ae9f4 100644
--- a/drivers/input/rmi4/rmi_f55.c
+++ b/drivers/input/rmi4/rmi_f55.c
@@ -52,6 +52,11 @@ static int rmi_f55_detect(struct rmi_function *fn)
 
 	f55->num_rx_electrodes = f55->qry[F55_NUM_RX_OFFSET];
 	f55->num_tx_electrodes = f55->qry[F55_NUM_TX_OFFSET];
+	if (!f55->num_rx_electrodes || !f55->num_tx_electrodes) {
+		rmi_dbg(RMI_DEBUG_FN, &fn->dev,
+			"F55 query returned no electrodes, giving up\n");
+		return 0;
+	}
 
 	f55->cfg_num_rx_electrodes = f55->num_rx_electrodes;
 	f55->cfg_num_tx_electrodes = f55->num_rx_electrodes;

-- 
2.42.0

[PATCH 5/7] Input: synaptics-rmi4 - don't do unaligned reads in IRQ context

[Caleb Connolly]

From: methanal <baclofen@tuta.io>

Some replacement displays include third-party touch ICs which incur a
significant penalty (1-2 seconds) when doing certain unaligned reads.
This is enough to break functionality when it happens in the hot path,
so adjust the interrupt handler to not read from an unaligned address.

Signed-off-by: methanal <baclofen@tuta.io>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
---
This solution does wind up doing the unaligned reads on the CPU instead,
although I'm not sure how significant of a penalty this is in practise.
---
 drivers/input/rmi4/rmi_driver.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
index cd3e4e77ab9b..58bf3dfbf81c 100644
--- a/drivers/input/rmi4/rmi_driver.c
+++ b/drivers/input/rmi4/rmi_driver.c
@@ -136,9 +136,14 @@ static int rmi_process_interrupt_requests(struct rmi_device *rmi_dev)
 		return 0;
 
 	if (!data->attn_data.data) {
+		/*
+		 * Read the device status register as well and ignore it.
+		 * Some aftermarket ICs have issues with interrupt requests
+		 * otherwise.
+		 */
 		error = rmi_read_block(rmi_dev,
-				data->f01_container->fd.data_base_addr + 1,
-				data->irq_status, data->num_of_irq_regs);
+				data->f01_container->fd.data_base_addr,
+				data->irq_status - 1, data->num_of_irq_regs + 1);
 		if (error < 0) {
 			dev_err(dev, "Failed to read irqs, code=%d\n", error);
 			return error;
@@ -1083,16 +1088,17 @@ int rmi_probe_interrupts(struct rmi_driver_data *data)
 	data->num_of_irq_regs = (data->irq_count + 7) / 8;
 
 	size = BITS_TO_LONGS(data->irq_count) * sizeof(unsigned long);
-	data->irq_memory = devm_kcalloc(dev, size, 4, GFP_KERNEL);
+	data->irq_memory = devm_kzalloc(dev, size * 4 + 1, GFP_KERNEL);
 	if (!data->irq_memory) {
 		dev_err(dev, "Failed to allocate memory for irq masks.\n");
 		return -ENOMEM;
 	}
 
-	data->irq_status	= data->irq_memory + size * 0;
-	data->fn_irq_bits	= data->irq_memory + size * 1;
-	data->current_irq_mask	= data->irq_memory + size * 2;
-	data->new_irq_mask	= data->irq_memory + size * 3;
+	/* The first byte is reserved for the device status register */
+	data->irq_status	= data->irq_memory + size * 0 + 1;
+	data->fn_irq_bits	= data->irq_memory + size * 1 + 1;
+	data->current_irq_mask	= data->irq_memory + size * 2 + 1;
+	data->new_irq_mask	= data->irq_memory + size * 3 + 1;
 
 	return retval;
 }

-- 
2.42.0

[PATCH 6/7] Input: synaptics-rmi4 - read product ID on aftermarket touch ICs

[Caleb Connolly]

From: methanal <baclofen@tuta.io>

Some replacement displays include third-party touch ICs which do not
report the product ID correctly unless we read directly from the
product ID register. Add a check and a fallback read to handle this.

Signed-off-by: methanal <baclofen@tuta.io>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
---
 drivers/input/rmi4/rmi_f01.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/input/rmi4/rmi_f01.c b/drivers/input/rmi4/rmi_f01.c
index d7603c50f864..4aee30d2dcde 100644
--- a/drivers/input/rmi4/rmi_f01.c
+++ b/drivers/input/rmi4/rmi_f01.c
@@ -250,6 +250,20 @@ static int rmi_f01_read_properties(struct rmi_device *rmi_dev,
 		}
 	}
 
+	/*
+	 * Some aftermarket ICs put garbage into the product id field unless
+	 * we read directly from the product id register.
+	 */
+	if (props->product_id[0] < 0x20) {
+		ret = rmi_read_block(rmi_dev, query_base_addr + 11,
+				       props->product_id, RMI_PRODUCT_ID_LENGTH);
+		if (ret) {
+			dev_err(&rmi_dev->dev,
+				"Failed to read product id: %d\n", ret);
+			return ret;
+		}
+	}
+
 	return 0;
 }
 

-- 
2.42.0

[PATCH 7/7] Input: synaptics-rmi4 - support fallback values for PDT descriptor bytes

[Caleb Connolly]

From: methanal <baclofen@tuta.io>

Some replacement displays include third-party touch ICs which do not
expose the function number and the interrupt status in its PDT entries.

OnePlus 6 (original touch IC)
  rmi4_i2c 12-0020: read 6 bytes at 0x00e3: 0 (2b 22 0d 06 01 01)

OnePlus 6 (aftermarket touch IC)
  rmi4_i2c 12-0020: read 6 bytes at 0x00e3: 0 (2c 23 0d 06 00 00)

Introduce a new devicetree property `syna,pdt-desc` which can be used to
provide platform-specific fallback values for users with a replacement
display with an aftermarket touch IC.

Signed-off-by: methanal <baclofen@tuta.io>
[codeflow adjustments, checkpatch fixes, wording]
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
---
 drivers/input/rmi4/rmi_driver.c | 67 ++++++++++++++++++++++++++++++++++++++---
 drivers/input/rmi4/rmi_driver.h |  2 ++
 include/linux/rmi.h             |  3 ++
 3 files changed, 67 insertions(+), 5 deletions(-)

diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
index 58bf3dfbf81c..5e1e3d5dd800 100644
--- a/drivers/input/rmi4/rmi_driver.c
+++ b/drivers/input/rmi4/rmi_driver.c
@@ -461,9 +461,10 @@ static int rmi_driver_reset_handler(struct rmi_device *rmi_dev)
 	return 0;
 }
 
-static int rmi_read_pdt_entry(struct rmi_device *rmi_dev,
-			      struct pdt_entry *entry, u16 pdt_address)
+static int rmi_read_pdt_entry(struct rmi_device *rmi_dev, struct pdt_entry *entry,
+			      struct pdt_scan_state *state, u16 pdt_address)
 {
+	const struct rmi_device_platform_data *pdata = rmi_get_platform_data(rmi_dev);
 	u8 buf[RMI_PDT_ENTRY_SIZE];
 	int error;
 
@@ -474,6 +475,21 @@ static int rmi_read_pdt_entry(struct rmi_device *rmi_dev,
 		return error;
 	}
 
+	if (pdata->pdt_fallback_size > state->pdt_count * RMI_OF_PDT_DESC_CELLS + 1) {
+		/* Use the description bytes from DT */
+		buf[5] = pdata->pdt_fallback_desc[state->pdt_count * RMI_OF_PDT_DESC_CELLS];
+		buf[4] = pdata->pdt_fallback_desc[state->pdt_count * RMI_OF_PDT_DESC_CELLS + 1];
+
+		error = rmi_read_block(rmi_dev, pdt_address, buf,
+				RMI_PDT_ENTRY_SIZE - 2);
+		if (error) {
+			dev_err(&rmi_dev->dev,
+					"Read PDT entry at %#06x failed, code: %d.\n",
+					pdt_address, error);
+			return error;
+		}
+	}
+
 	entry->page_start = pdt_address & RMI4_PAGE_MASK;
 	entry->query_base_addr = buf[0];
 	entry->command_base_addr = buf[1];
@@ -551,7 +567,7 @@ static int rmi_scan_pdt_page(struct rmi_device *rmi_dev,
 	int retval;
 
 	for (addr = pdt_start; addr >= pdt_end; addr -= RMI_PDT_ENTRY_SIZE) {
-		error = rmi_read_pdt_entry(rmi_dev, &pdt_entry, addr);
+		error = rmi_read_pdt_entry(rmi_dev, &pdt_entry, state, addr);
 		if (error)
 			return error;
 
@@ -1028,9 +1044,11 @@ static int rmi_driver_remove(struct device *dev)
 }
 
 #ifdef CONFIG_OF
-static int rmi_driver_of_probe(struct device *dev,
+static int rmi_driver_of_probe(struct rmi_device *rmi_dev,
 				struct rmi_device_platform_data *pdata)
 {
+	struct device *dev = rmi_dev->xport->dev;
+	u8 buf[RMI_PDT_ENTRY_SIZE];
 	int retval;
 
 	retval = rmi_of_property_read_u32(dev, &pdata->reset_delay_ms,
@@ -1038,6 +1056,45 @@ static int rmi_driver_of_probe(struct device *dev,
 	if (retval)
 		return retval;
 
+	/*
+	 * In some aftermerket touch ICs, the first PDT entry is empty and
+	 * the function number register is 0. If so, the platform
+	 * may have provided backup PDT entries in the device tree.
+	 */
+
+	retval = rmi_read_block(rmi_dev, PDT_START_SCAN_LOCATION,
+			buf, RMI_PDT_ENTRY_SIZE);
+	if (retval) {
+		dev_err(dev, "Read PDT entry at %#06x failed, code: %d.\n",
+			PDT_START_SCAN_LOCATION, retval);
+		return retval;
+	}
+
+	if (!RMI4_END_OF_PDT(buf[5]))
+		return 0;
+
+	pdata->pdt_fallback_size = of_property_count_u8_elems(dev->of_node,
+						  "syna,pdt-fallback-desc");
+
+	/* The rmi4 driver would fail later anyway, so just error out now. */
+	if (pdata->pdt_fallback_size == -EINVAL) {
+		dev_err(dev, "First PDT entry is empty and no backup values provided\n");
+		return -EINVAL;
+	}
+
+	if (pdata->pdt_fallback_size < 0) {
+		dev_err(dev, "syna,ptd-desc property was not specified properly: %d\n",
+			pdata->pdt_fallback_size);
+		return pdata->pdt_fallback_size;
+	}
+
+	pdata->pdt_fallback_desc = devm_kzalloc(dev, pdata->pdt_fallback_size, GFP_KERNEL);
+
+	retval = of_property_read_u8_array(dev->of_node, "syna,pdt-fallback-desc",
+		pdata->pdt_fallback_desc, pdata->pdt_fallback_size);
+	if (retval < 0)
+		return retval;
+
 	return 0;
 }
 #else
@@ -1163,7 +1220,7 @@ static int rmi_driver_probe(struct device *dev)
 	pdata = rmi_get_platform_data(rmi_dev);
 
 	if (rmi_dev->xport->dev->of_node) {
-		retval = rmi_driver_of_probe(rmi_dev->xport->dev, pdata);
+		retval = rmi_driver_of_probe(rmi_dev, pdata);
 		if (retval)
 			return retval;
 	}
diff --git a/drivers/input/rmi4/rmi_driver.h b/drivers/input/rmi4/rmi_driver.h
index e1a5412f2f8f..2531c32d6163 100644
--- a/drivers/input/rmi4/rmi_driver.h
+++ b/drivers/input/rmi4/rmi_driver.h
@@ -31,6 +31,8 @@
 #define RMI_PDT_FUNCTION_VERSION_MASK   0x60
 #define RMI_PDT_INT_SOURCE_COUNT_MASK   0x07
 
+#define RMI_OF_PDT_DESC_CELLS 2
+
 #define PDT_START_SCAN_LOCATION 0x00e9
 #define PDT_END_SCAN_LOCATION	0x0005
 #define RMI4_END_OF_PDT(id) ((id) == 0x00 || (id) == 0xff)
diff --git a/include/linux/rmi.h b/include/linux/rmi.h
index ab7eea01ab42..974597960b5e 100644
--- a/include/linux/rmi.h
+++ b/include/linux/rmi.h
@@ -214,6 +214,9 @@ struct rmi_device_platform_data {
 	int reset_delay_ms;
 	int irq;
 
+	u8 *pdt_fallback_desc;
+	int pdt_fallback_size;
+
 	struct rmi_device_platform_data_spi spi_data;
 
 	/* function handler pdata */

-- 
2.42.0

Re: [PATCH 1/7] dt-bindings: input: syna,rmi4: document syna,pdt-fallback-desc

[Rob Herring]

On Sat, Sep 30, 2023 at 06:08:45PM +0100, Caleb Connolly wrote:
> This new property allows devices to specify some register values which
> are missing on units with third party replacement displays. These
> displays use unofficial touch ICs which only implement a subset of the
> RMI4 specification.
> 
> Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
> ---
> To: "Jason A. Donenfeld" <Jason@zx2c4.com>
> To: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
> To: Rob Herring <robh+dt@kernel.org>
> To: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
> To: Conor Dooley <conor+dt@kernel.org>
> Cc: devicetree@vger.kernel.org
> ---
>  Documentation/devicetree/bindings/input/syna,rmi4.yaml | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/input/syna,rmi4.yaml b/Documentation/devicetree/bindings/input/syna,rmi4.yaml
> index 4d4e1a8e36be..bd6beb67ac21 100644
> --- a/Documentation/devicetree/bindings/input/syna,rmi4.yaml
> +++ b/Documentation/devicetree/bindings/input/syna,rmi4.yaml
> @@ -49,6 +49,16 @@ properties:
>      description:
>        Delay to wait after powering on the device.
>  
> +  syna,pdt-fallback-desc:
> +    $ref: /schemas/types.yaml#/definitions/uint8-array
> +    description:
> +      An array of pairs of function number and version. These are used

array of pairs is a matrix, not array. Or it is just 2 values? Needs 
some size constraints.


> +      on some devices with replacement displays that use unofficial touch
> +      controllers. These controllers do report the properties of their PDT

PDT?

> +      entries, but leave the function_number and function_version registers
> +      blank. These values should match exactly the 5th and 4th bytes of each
> +      PDT entry from the original display's touch controller.
> +
>    vdd-supply: true
>    vio-supply: true
>  
> 
> -- 
> 2.42.0
> 

Re: [PATCH 3/7] Input: synaptics-rmi4 - f12: use hardcoded values for aftermarket touch ICs

[Pavel Machek]

Hi!

> Some replacement displays include third-party touch ICs which are
> devoid of register descriptors. Create a fake data register descriptor
> for such ICs and provide hardcoded default values.
> 
> It isn't possible to reliably determine if the touch IC is original or
> not, so these fallback values are offered as an alternative to the error
> path when register descriptors aren't available.
> 
> Signed-off-by: methanal <baclofen@tuta.io>

I guess we should have full/real name here.

Best regards,
							Pavel
							
-- 

Re: [PATCH 3/7] Input: synaptics-rmi4 - f12: use hardcoded values for aftermarket touch ICs

[Caleb Connolly]

On 28/10/2023 11:40, Pavel Machek wrote:
> Hi!
> 
>> Some replacement displays include third-party touch ICs which are
>> devoid of register descriptors. Create a fake data register descriptor
>> for such ICs and provide hardcoded default values.
>>
>> It isn't possible to reliably determine if the touch IC is original or
>> not, so these fallback values are offered as an alternative to the error
>> path when register descriptors aren't available.
>>
>> Signed-off-by: methanal <baclofen@tuta.io>
> 
> I guess we should have full/real name here.

I must disagree [1] [2]. These patches have my SoB and are being sent by
me on behalf of the author, who has no interest in contributing upstream.

[1]:
https://lore.kernel.org/lkml/c1bf62a2-e381-c796-2219-17a578987a76@marcan.st/T/

[2]:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=d4563201f33a022fc0353033d9dfeb1606a88330
> 
> Best regards,
> 							Pavel
> 							

-- 
// Caleb (they/them)