From: Jiada Wang <jiada_wang@mentor.com> To: <nick@shmanahar.org>, <dmitry.torokhov@gmail.com> Cc: <linux-input@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <jiada_wang@mentor.com>, <george_davis@mentor.com> Subject: [PATCH v2 37/49] Input: atmel_mxt_ts: Limit the max bytes transferred in an i2c transaction Date: Tue, 27 Aug 2019 15:30:42 +0900 [thread overview] Message-ID: <20190827063054.20883-3-jiada_wang@mentor.com> (raw) In-Reply-To: <20190827063054.20883-1-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> --- .../bindings/input/atmel,maxtouch.txt | 3 + drivers/input/touchscreen/atmel_mxt_ts.c | 65 +++++++++++++++---- 2 files changed, 54 insertions(+), 14 deletions(-) diff --git a/Documentation/devicetree/bindings/input/atmel,maxtouch.txt b/Documentation/devicetree/bindings/input/atmel,maxtouch.txt index d7db16920083..62c93d94bc5d 100644 --- a/Documentation/devicetree/bindings/input/atmel,maxtouch.txt +++ b/Documentation/devicetree/bindings/input/atmel,maxtouch.txt @@ -42,6 +42,8 @@ Optional properties for main touchpad device: - atmel,input_name: Override name of input device from the default. +- atmel,mtu: Maximum number of bytes that can read/transferred in an i2c transaction + Example: touch@4b { @@ -49,4 +51,5 @@ Example: reg = <0x4b>; interrupt-parent = <&gpio>; interrupts = <TEGRA_GPIO(W, 3) IRQ_TYPE_LEVEL_LOW>; + atmel,mtu = <200> }; diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c index aa33962ed1dc..169107413823 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 { @@ -4110,6 +4143,10 @@ 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; } -- 2.19.2
WARNING: multiple messages have this Message-ID (diff)
From: Jiada Wang <jiada_wang@mentor.com> To: nick@shmanahar.org, dmitry.torokhov@gmail.com Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, jiada_wang@mentor.com, george_davis@mentor.com Subject: [PATCH v2 37/49] Input: atmel_mxt_ts: Limit the max bytes transferred in an i2c transaction Date: Tue, 27 Aug 2019 15:30:42 +0900 [thread overview] Message-ID: <20190827063054.20883-3-jiada_wang@mentor.com> (raw) In-Reply-To: <20190827063054.20883-1-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> --- .../bindings/input/atmel,maxtouch.txt | 3 + drivers/input/touchscreen/atmel_mxt_ts.c | 65 +++++++++++++++---- 2 files changed, 54 insertions(+), 14 deletions(-) diff --git a/Documentation/devicetree/bindings/input/atmel,maxtouch.txt b/Documentation/devicetree/bindings/input/atmel,maxtouch.txt index d7db16920083..62c93d94bc5d 100644 --- a/Documentation/devicetree/bindings/input/atmel,maxtouch.txt +++ b/Documentation/devicetree/bindings/input/atmel,maxtouch.txt @@ -42,6 +42,8 @@ Optional properties for main touchpad device: - atmel,input_name: Override name of input device from the default. +- atmel,mtu: Maximum number of bytes that can read/transferred in an i2c transaction + Example: touch@4b { @@ -49,4 +51,5 @@ Example: reg = <0x4b>; interrupt-parent = <&gpio>; interrupts = <TEGRA_GPIO(W, 3) IRQ_TYPE_LEVEL_LOW>; + atmel,mtu = <200> }; diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c index aa33962ed1dc..169107413823 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 { @@ -4110,6 +4143,10 @@ 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; } -- 2.19.2
next prev parent reply other threads:[~2019-08-27 6:30 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-27 6:30 [PATCH v2 35/49] input: atmel_mxt_ts: Add Missing Delay for reset handling of Atmel touch panel controller in detachable displays Jiada Wang 2019-08-27 6:30 ` Jiada Wang 2019-08-27 6:30 ` [PATCH v2 36/49] Input: atmel_mxt_ts: Add support for run self-test routine Jiada Wang 2019-08-27 6:30 ` Jiada Wang 2019-08-27 6:30 ` Jiada Wang [this message] 2019-08-27 6:30 ` [PATCH v2 37/49] Input: atmel_mxt_ts: Limit the max bytes transferred in an i2c transaction Jiada Wang 2019-08-27 6:30 ` [PATCH v2 38/49] Input: atmel_mxt_ts: return error from mxt_process_messages_until_invalid() Jiada Wang 2019-08-27 6:30 ` Jiada Wang 2019-08-27 6:30 ` [PATCH v2 39/49] Input: Atmel: improve error handling in mxt_start() Jiada Wang 2019-08-27 6:30 ` Jiada Wang
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