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From: Jiada Wang <jiada_wang@mentor.com>
To: <nick@shmanahar.org>, <dmitry.torokhov@gmail.com>,
	<jikos@kernel.org>, <benjamin.tissoires@redhat.com>,
	<bsz@semihalf.com>, <rydberg@bitmath.org>
Cc: <linux-input@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<erosca@de.adit-jv.com>, <Andrew_Gabbasov@mentor.com>,
	<jiada_wang@mentor.com>
Subject: [PATCH v9 42/55] Input: atmel_mxt_ts: Limit the max bytes transferred in an i2c transaction
Date: Wed, 25 Mar 2020 06:33:21 -0700	[thread overview]
Message-ID: <20200325133334.19346-43-jiada_wang@mentor.com> (raw)
In-Reply-To: <20200325133334.19346-1-jiada_wang@mentor.com>

From: Balasubramani Vivekanandan <balasubramani_vivekanandan@mentor.com>

In mxt_process_messages_until_invalid() function, driver tries to read
all possible reportid in a single i2c transaction. Number of bytes read
is limited by the max_reportid parameter.
If the max_reportid is a very large value, then a large chunk of bytes
will be requested from the controller in a single i2c transaction.
This transaction can fail due to timeout. This is visible when the
Atmel controller is connected to the SOC via a i2c mux hardware.

mxt_process_messages_t44() reads the T44 message which contains the
pending T5 message count. If the number of pending T5 messages returned
by T44 message is too high then there is a risk of i2c transaction
timeout while reading T5 messages in mxt_process_messages_t44().

New property 'atmel,mtu' is created. This property limits the maximum
number of bytes that can read/transferred in an i2c transcation

Signed-off-by: Balasubramani Vivekanandan <balasubramani_vivekanandan@mentor.com>
Signed-off-by: George G. Davis <george_davis@mentor.com>
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 65 +++++++++++++++++++-----
 1 file changed, 51 insertions(+), 14 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 54cd6219cbaa..384b53717139 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -417,6 +417,7 @@ struct mxt_data {
 	/* Indicates whether device is updating configuration */
 	bool updating_config;
 
+	unsigned int mtu;
 	bool t25_status;
 };
 
@@ -1462,11 +1463,32 @@ static int mxt_read_and_process_messages(struct mxt_data *data, u8 count)
 	return num_valid;
 }
 
+static u8 mxt_max_msg_read_count(struct mxt_data *data, u8 max_T5_msg_count)
+{
+	u8 T5_msg_count_limit = data->mtu / data->T5_msg_size;
+
+	if (!data->mtu)
+		return max_T5_msg_count;
+
+	if (data->mtu < data->T5_msg_size) {
+		WARN(1, "mtu set is lesser than the T5 message size\n");
+		/* Return count of 1, as fallback */
+		return 1;
+	}
+	/*
+	 * Return maximum number of T5 messages in single i2c transaction
+	 * based on "atmel,mtu" property.
+	 */
+	return min(T5_msg_count_limit, max_T5_msg_count);
+}
+
 static irqreturn_t mxt_process_messages_t44(struct mxt_data *data)
 {
 	struct device *dev = &data->client->dev;
 	int ret;
-	u8 count, num_left;
+	u8 T5_msg_count, total_pending;
+	u8 total_processed = 0;
+	u8 processed_valid = 0;
 
 	/* Read T44 and T5 together */
 	ret = __mxt_read_reg(data->client, data->T44_address,
@@ -1476,18 +1498,19 @@ static irqreturn_t mxt_process_messages_t44(struct mxt_data *data)
 		return IRQ_NONE;
 	}
 
-	count = data->msg_buf[0];
+	T5_msg_count = data->msg_buf[0];
 
 	/*
 	 * This condition may be caused by the CHG line being configured in
 	 * Mode 0. It results in unnecessary I2C operations but it is benign.
 	 */
-	if (count == 0)
+	if (!T5_msg_count)
 		return IRQ_NONE;
 
-	if (count > data->max_reportid) {
-		dev_warn(dev, "T44 count %d exceeded max report id\n", count);
-		count = data->max_reportid;
+	if (T5_msg_count > data->max_reportid) {
+		dev_warn(dev, "T44 count %d exceeded max report id\n",
+			 T5_msg_count);
+		T5_msg_count = data->max_reportid;
 	}
 
 	/* Process first message */
@@ -1497,16 +1520,25 @@ static irqreturn_t mxt_process_messages_t44(struct mxt_data *data)
 		return IRQ_NONE;
 	}
 
-	num_left = count - 1;
+	total_pending = T5_msg_count - 1;
+	if (!total_pending)
+		goto end;
 
 	/* Process remaining messages if necessary */
-	if (num_left) {
-		ret = mxt_read_and_process_messages(data, num_left);
+	T5_msg_count = mxt_max_msg_read_count(data, total_pending);
+
+	do {
+		if ((total_pending - total_processed) < T5_msg_count)
+			T5_msg_count = total_pending - total_processed;
+		ret = mxt_read_and_process_messages(data, T5_msg_count);
 		if (ret < 0)
 			goto end;
-		else if (ret != num_left)
-			dev_warn(dev, "Unexpected invalid message\n");
-	}
+		total_processed += T5_msg_count;
+		processed_valid += ret;
+	} while (total_processed < total_pending);
+
+	if (processed_valid != total_pending)
+		dev_warn(dev, "Unexpected invalid message\n");
 
 end:
 	if (data->update_input) {
@@ -1521,9 +1553,10 @@ static int mxt_process_messages_until_invalid(struct mxt_data *data)
 {
 	struct device *dev = &data->client->dev;
 	int count, read;
-	u8 tries = 2;
+	int tries;
 
-	count = data->max_reportid;
+	count = mxt_max_msg_read_count(data, data->max_reportid);
+	tries = (data->max_reportid / count) + 1;
 
 	/* Read messages until we force an invalid */
 	do {
@@ -4120,6 +4153,10 @@ static int mxt_parse_device_properties(struct mxt_data *data)
 
 	device_property_read_u32(dev, "atmel,suspend-mode",
 				 &data->suspend_mode);
+	device_property_read_u32(dev, "atmel,mtu", &data->mtu);
+	if (data->mtu)
+		dev_dbg(dev, "mtu is set as %d\n", data->mtu);
+
 	return 0;
 }
 
-- 
2.17.1


  parent reply	other threads:[~2020-03-25 13:36 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-25 13:32 [PATCH v9 00/55] atmel_mxt_ts misc Jiada Wang
2020-03-25 13:32 ` [PATCH v9 01/55] Input: introduce input_mt_report_slot_inactive Jiada Wang
2020-03-25 13:32 ` [PATCH v9 02/55] Input: atmel_mxt_ts - rework sysfs init/remove Jiada Wang
2020-03-25 13:32 ` [PATCH v9 03/55] Input: atmel_mxt_ts - only read messages in mxt_acquire_irq() when necessary Jiada Wang
2020-03-25 13:32 ` [PATCH v9 04/55] Input: atmel_mxt_ts - split large i2c transfers into blocks Jiada Wang
2020-03-25 13:32 ` [PATCH v9 05/55] Input: atmel_mxt_ts - output status from T48 Noise Supression Jiada Wang
2020-03-25 13:32 ` [PATCH v9 06/55] Input: atmel_mxt_ts - output status from T42 Touch Suppression Jiada Wang
2020-03-25 13:32 ` [PATCH v9 07/55] Input: atmel_mxt_ts - implement T9 vector/orientation support Jiada Wang
2020-03-25 13:32 ` [PATCH v9 08/55] Input: atmel_mxt_ts - implement T15 Key Array support Jiada Wang
2020-03-25 13:32 ` [PATCH v9 09/55] Input: atmel_mxt_ts - handle reports from T47 Stylus object Jiada Wang
2020-03-25 13:32 ` [PATCH v9 10/55] Input: atmel_mxt_ts - implement support for T107 active stylus Jiada Wang
2020-03-25 13:32 ` [PATCH v9 11/55] Input: atmel_mxt_ts - add debug for T92 gesture and T93 touch seq msgs Jiada Wang
2020-03-25 13:32 ` [PATCH v9 12/55] Input: atmel_mxt_ts - release touch state during suspend Jiada Wang
2020-03-25 13:32 ` [PATCH v9 13/55] Input: atmel_mxt_ts - add regulator control support Jiada Wang
2020-03-25 19:05   ` Dmitry Osipenko
2020-03-27 11:09     ` Wang, Jiada
2020-03-29 18:54       ` Dmitry Osipenko
2020-03-30  4:10         ` Wang, Jiada
2020-03-25 13:32 ` [PATCH v9 14/55] dt-bindings: input: atmel: add suspend mode support Jiada Wang
2020-03-25 13:32 ` [PATCH v9 15/55] Input: atmel_mxt_ts - report failures in suspend/resume Jiada Wang
2020-03-25 13:32 ` [PATCH v9 16/55] Input: atmel_mxt_ts - allow specification of firmware file name Jiada Wang
2020-03-25 13:32 ` [PATCH v9 17/55] Input: atmel_mxt_ts: Rename mxt_fw_version_show to fw_version_show Jiada Wang
2020-03-25 13:32 ` [PATCH v9 18/55] Input: atmel_mxt_ts: Rename mxt_hw_version_show to hw_version_show Jiada Wang
2020-03-25 13:32 ` [PATCH v9 19/55] Input: atmel_mxt_ts: rename mxt_update_fw_store to update_fw_store Jiada Wang
2020-03-25 13:32 ` [PATCH v9 20/55] Input: atmel_mxt_ts - handle cfg filename via pdata/sysfs Jiada Wang
2020-03-25 13:33 ` [PATCH v9 21/55] dt-bindings: input: atmel: provide name of configuration file Jiada Wang
2020-03-25 13:33 ` [PATCH v9 22/55] Input: atmel_mxt_ts - allow input name to be specified in platform data Jiada Wang
2020-03-25 13:33 ` [PATCH v9 23/55] dt-bindings: input: atmel: support to specify input name Jiada Wang
2020-03-25 13:33 ` [PATCH v9 24/55] Input: atmel_mxt_ts - add config checksum attribute to sysfs Jiada Wang
2020-03-25 13:33 ` [PATCH v9 25/55] Input: atmel_mxt_ts - refactor firmware flash to extract context into struct Jiada Wang
2020-03-25 13:33 ` [PATCH v9 26/55] Input: atmel_mxt_ts - refactor code to enter bootloader into separate func Jiada Wang
2020-03-25 13:33 ` [PATCH v9 27/55] Input: atmel_mxt_ts - combine bootloader version query with probe Jiada Wang
2020-03-25 13:33 ` [PATCH v9 28/55] Input: atmel_mxt_ts - improve bootloader state machine handling Jiada Wang
2020-03-25 13:33 ` [PATCH v9 29/55] Input: atmel_mxt_ts - rename bl_completion to chg_completion Jiada Wang
2020-03-25 13:33 ` [PATCH v9 30/55] Input: atmel_mxt_ts - make bootloader interrupt driven Jiada Wang
2020-03-25 13:33 ` [PATCH v9 31/55] Input: atmel_mxt_ts - delay enabling IRQ when not using regulators Jiada Wang
2020-03-25 13:33 ` [PATCH v9 32/55] Input: atmel_mxt_ts - implement I2C retries Jiada Wang
2020-03-25 13:33 ` [PATCH v9 33/55] Input: atmel_mxt_ts - orientation is not present in hover Jiada Wang
2020-03-25 13:33 ` [PATCH v9 34/55] Input: atmel_mxt_ts - implement debug output for messages Jiada Wang
2020-03-25 13:33 ` [PATCH v9 35/55] Input: atmel_mxt_ts - implement improved debug message interface Jiada Wang
2020-03-25 13:33 ` [PATCH v9 36/55] Input: atmel_mxt_ts - eliminate data->raw_info_block Jiada Wang
2020-03-25 13:33 ` [PATCH v9 37/55] Input: atmel_mxt_ts - Change call-points of mxt_free_* functions Jiada Wang
2020-03-25 13:33 ` [PATCH v9 38/55] Input: atmel_mxt_ts - rely on calculated_crc rather than file config_crc Jiada Wang
2020-03-25 13:33 ` [PATCH v9 39/55] input: atmel_mxt_ts: export GPIO reset line via sysfs Jiada Wang
2020-03-25 13:33 ` [PATCH v9 40/55] input: atmel_mxt_ts: Add Missing Delay for reset handling of Atmel touch panel controller in detachable displays Jiada Wang
2020-03-25 13:33 ` [PATCH v9 41/55] Input: atmel_mxt_ts: Add support for run self-test routine Jiada Wang
2020-03-25 13:33 ` Jiada Wang [this message]
2020-03-25 13:33 ` [PATCH v9 43/55] dt-bindings: input: atmel: support to set max bytes transferred Jiada Wang
2020-03-25 13:33 ` [PATCH v9 44/55] Input: atmel_mxt_ts: return error from mxt_process_messages_until_invalid() Jiada Wang
2020-03-25 13:33 ` [PATCH v9 45/55] Input: Atmel: improve error handling in mxt_start() Jiada Wang
2020-03-25 13:33 ` [PATCH v9 46/55] Input: Atmel: improve error handling in mxt_initialize() Jiada Wang
2020-03-25 13:33 ` [PATCH v9 47/55] Input: Atmel: improve error handling in mxt_update_cfg() Jiada Wang
2020-03-25 13:33 ` [PATCH v9 48/55] Input: Atmel: Improve error handling in mxt_initialize_input_device() Jiada Wang
2020-03-25 13:33 ` [PATCH v9 49/55] Input: Atmel: handle ReportID "0x00" while processing T5 messages Jiada Wang
2020-03-25 13:33 ` [PATCH v9 50/55] Input: Atmel: use T44 object to process " Jiada Wang
2020-03-25 13:33 ` [PATCH v9 51/55] Input: atmel_mxt_ts: use gpiod_set_value_cansleep for reset pin Jiada Wang
2020-03-25 13:33 ` [PATCH v9 52/55] input: touchscreen: atmel_mxt_ts: Added sysfs entry for touchscreen status Jiada Wang
2020-03-25 19:35   ` Dmitry Osipenko
2020-03-25 19:41     ` Dmitry Osipenko
2020-03-27 12:49     ` Wang, Jiada
2020-03-27 13:37       ` Dmitry Osipenko
2020-03-27 13:43         ` Dmitry Osipenko
2020-03-25 13:33 ` [PATCH v9 53/55] input: atmel_mxt_ts: added sysfs interface to update atmel T38 data Jiada Wang
2020-03-25 13:33 ` [PATCH v9 54/55] Input: atmel_mxt_ts: Implement synchronization during various operation Jiada Wang
2020-03-25 13:33 ` [PATCH v9 55/55] Input: atmel_mxt_ts - Fix compilation warning Jiada Wang

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