From: Balasubramani Vivekanandan <[email protected]>
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. 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 <[email protected]> Signed-off-by: George G. Davis <[email protected]> Signed-off-by: Jiada Wang <[email protected]> --- .../bindings/input/atmel,maxtouch.txt | 3 +++ drivers/input/touchscreen/atmel_mxt_ts.c | 26 +++++++++++++++++-- 2 files changed, 27 insertions(+), 2 deletions(-) diff --git a/Documentation/devicetree/bindings/input/atmel,maxtouch.txt b/Documentation/devicetree/bindings/input/atmel,maxtouch.txt index 7afe12a93202..a7f9a8e551f7 100644 --- a/Documentation/devicetree/bindings/input/atmel,maxtouch.txt +++ b/Documentation/devicetree/bindings/input/atmel,maxtouch.txt @@ -45,6 +45,8 @@ Optional properties for main touchpad device: - atmel,gpios: Specify the GPIO input pins whose status will be read via the /sys/class/input/input<n>/backlight_error<x> sysfs entries. +- atmel,mtu: Maximum number of bytes that can read/transferred in an i2c transaction + Example: touch@4b { @@ -52,6 +54,7 @@ Example: reg = <0x4b>; interrupt-parent = <&gpio>; interrupts = <TEGRA_GPIO(W, 3) IRQ_TYPE_LEVEL_LOW>; + atmel,mtu = <200> atmel,gpios { backlight_error1 { diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c index c6ba061098c0..e315ad3a8d2a 100644 --- a/drivers/input/touchscreen/atmel_mxt_ts.c +++ b/drivers/input/touchscreen/atmel_mxt_ts.c @@ -421,6 +421,7 @@ struct mxt_data { unsigned long gpio_input_pin_status; struct attribute_group gpio_attrs; unsigned long gpio_input_pin_status_default; + unsigned int mtu; bool t25_status; }; @@ -1522,13 +1523,30 @@ static irqreturn_t mxt_process_messages_t44(struct mxt_data *data) return IRQ_HANDLED; } +static u8 mxt_max_msg_read_count(struct mxt_data *data) +{ + u8 count_limit = data->mtu / data->T5_msg_size; + + if (!data->mtu) + return data->max_reportid; + + 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 min(count_limit, data->max_reportid); +} + 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); + tries = (data->max_reportid / count) + 1; /* Read messages until we force an invalid */ do { @@ -4290,6 +4308,10 @@ static int mxt_parse_device_properties(struct mxt_data *data) of_node_put(np_gpio); } + 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; err_gpios_property_put: -- 2.19.2
