Commit 99ce264d authored by Andrzej Głąbek's avatar Andrzej Głąbek Committed by Carles Cufi
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drivers: i2c_nrfx_twim: Use concatenation buffer by default 



Issue an error logging message when the i2c_nrfx_twim driver lacks
a concatenation buffer big enough to properly handle a call to
i2c_burst_write() function, to give the user a hint what is wrong.

Also use by default a 16-bytes long concatenation buffer for every
instance of the i2c_nrfx_twim driver. Such value should cover most
of the simple uses of the i2c_burst_write() function, like those
in the stmemsc sensor drivers, and when a longer buffer is needed,
the user will be provided with the above message pointing to the
property that should be adjusted.

Signed-off-by: default avatarAndrzej Głąbek <andrzej.glabek@nordicsemi.no>
parent 4801cbd9

drivers/i2c/i2c_nrfx_twim.c

+17 −12
Original line number Diff line number Diff line
@@ -65,13 +65,13 @@ static int i2c_nrfx_twim_transfer(const struct device *dev, 
			break;

		}



		/* Merge this fragment with the next if we have a buffer, this

		 * isn't the last fragment, it doesn't end a bus transaction,

		 * the next one doesn't start a bus transaction, and the

		 * direction of the next fragment is the same as this one.

		/* This fragment needs to be merged with the next one if:

		 * - it is not the last fragment

		 * - it does not end a bus transaction

		 * - the next fragment does not start a bus transaction

		 * - the direction of the next fragment is the same as this one

		 */

		bool concat_next = (concat_buf_size > 0)

			&& ((i + 1) < num_msgs)

		bool concat_next = ((i + 1) < num_msgs)

				&& !(msgs[i].flags & I2C_MSG_STOP)

				&& !(msgs[i + 1].flags & I2C_MSG_RESTART)

				&& ((msgs[i].flags & I2C_MSG_READ)
@@ -83,8 +83,13 @@ static int i2c_nrfx_twim_transfer(const struct device *dev, 
		 */

		if (concat_next || (concat_len != 0)) {

			if ((concat_len + msgs[i].len) > concat_buf_size) {

				LOG_ERR("concat-buf overflow: %u + %u > %u",

					concat_len, msgs[i].len, concat_buf_size);

				LOG_ERR("Need to use concatenation buffer and "

					"provided size is insufficient "

					"(%u + %u > %u). "

					"Adjust the zephyr,concat-buf-size "

					"property in the \"%s\" node.",

					concat_len, msgs[i].len,

					concat_buf_size, dev->name);

				ret = -ENOSPC;

				break;

			}

dts/bindings/i2c/nordic,nrf-twim.yaml

+7 −5
Original line number Diff line number Diff line
@@ -29,10 +29,12 @@ properties: 
    zephyr,concat-buf-size:

        type: int

        required: false

        description:

            If concatenation buffer size is set, then multiple messages in the

            same direction will be concatenated into single transfers as long

            as there is space in buffer and no restart or stop flag is set.

        default: 16

        description: |

            Size of a concatenation buffer that the driver is to use for merging

            multiple same direction I2C messages that have no RESTART or STOP

            flag between them (see e.g. the i2c_burst_write() function) into one

            transfer on the bus.



            This property must be provided when interacting with devices like

            the SSD1306 display that cannot tolerate a repeated start and

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