Bluetooth: HCI: Reword BT_BUF_ACL_*
description
Some part of the descriptions were wrong. Also, the description of `BT_BUF_ACL_RX_SIZE` was too verbose and no longer needed with the updated L2CAP documentation. Signed-off-by: Théo Battrel <theo.battrel@nordicsemi.no>
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1 changed files with 14 additions and 27 deletions
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@ -14,13 +14,14 @@ config BT_BUF_ACL_TX_SIZE
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help
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Maximum supported ACL size of data packets sent from the Host to the
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Controller. This value does not include the HCI ACL header.
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The Host will segment the data transmitted to the Controller so that
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packets sent to the Controller will contain data up to this size.
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In a combined build this value will be set in both the Host and the
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Controller.
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In a Host-only build the Host will read the maximum ACL size supported
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by the Controller and use the smallest value supported by both the
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Host and the Controller.
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The Host supports sending of larger L2CAP PDUs than the ACL size and
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will fragment L2CAP PDUs into ACL data packets.
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The Controller will return this value in the HCI LE Read Buffer
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@ -60,37 +61,21 @@ config BT_BUF_ACL_RX_SIZE
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help
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Maximum support ACL size of data packets sent from the Controller to
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the Host. This value does not include the HCI ACL header.
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In a combined Host and Controller build the buffer sizes in both the
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Host and the Controller will use this value for buffer sizes, and
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therefore Controller to Host flow Controller is not needed.
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In a combined Host and Controller build, both the
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Host and the Controller will use this value for buffer sizes, making
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Controller to Host flow control not strictly necessary.
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In a Host only build with Controller to Host flow control enabled
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the Host will inform the Controller about the maximum ACL data size it
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can send by setting this value in the Host Buffer Size command.
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If Controller to Host flow control is not enabled then the Controller
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can assume the Host has infinite buffer size so this value should then
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be set to something that is guaranteed the Controller will not exceed
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or the data packets will be dropped.
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can assume the Host has to receive and process ACL data faster than
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the controller can produce it.
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In a Controller only build this will determine the maximum ACL size
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that the Controller will send to the Host.
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The Host supports reassembling of L2CAP PDUs from ACL data packets,
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but the maximum supported L2CAP PDU size is limited by the maximum
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supported ACL size.
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This means the maximum L2CAP PDU MTU is restricted by the maximum ACL
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size subtracting the 4 byte header of an L2CAP PDU.
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When using L2CAP Connection oriented Channels without segmentation
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then the L2CAP SDU MTU is also restricted by the maximum ACL size
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subtracting the 4 Byte header of an L2CAP PDU plus the 2 byte header
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of an L2CAP SDU.
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With Enhanced ATT enabled the minimum of 70 is needed to support the
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minimum ATT_MTU of 64 octets in an L2CAP SDU without segmentation.
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With SMP LE Secure Connections enabled the minimum of 69 is needed to
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support the minimum SMP MTU of 65 octets (public key + opcode) in an
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L2CAP PDU.
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An L2CAP PDU is also referred to as an L2CAP basic frame or B-frame.
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An L2CAP SDU is also referred to as an L2CAP Credit-based frame or
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K-frame.
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config BT_BUF_ACL_RX_COUNT
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int "Number of incoming ACL data buffers"
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@ -102,9 +87,11 @@ config BT_BUF_ACL_RX_COUNT
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Host.
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In a combined Host and Controller build the buffers are shared and
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therefore Controller to Host flow control is not needed.
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In a Host only build with Controller to Host flow control enabled
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the Host will inform the Controller about the maximum number of
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buffers by setting this value in the Host Buffer Size command.
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When Controller to Host flow control is not enabled the Controller
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can assume that the Host has infinite amount of buffers.
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