ARM CoreLink QoS-400 Network Interconnect Advanced Quality of Service Supplement to CoreLink NIC-400 Network Interconnect Technical Reference Manual: 3.3.2. Maximum Number of Outstanding Transactions Register

3.3.2. Maximum Number of Outstanding Transactions Register

The max_ot Register characteristics are:

Purpose

This register enables you to program the maximum number of address requests for the AR and AW channels. See Outstanding transaction regulation for more information.

The outstanding transaction limits have an integer part and a fractional part as follows:

ar_max_oti: Corresponds to the integer part of the maximum outstanding AR addresses.
aw_max_oti: Corresponds to the integer part of the maximum outstanding AW addresses.
ar_max_otf: Corresponds to the fractional part of the maximum outstanding AR addresses.
aw_max_otf: Corresponds to the fractional part of the maximum outstanding AW addresses.

A value of 0 for both the integer and fractional parts disables the programmable regulation so that the NIC-400 base product configuration limits apply.

The AW and AR outstanding transaction limits are enabled when you set the corresponding en_aw_ot or en_ar_ot control bits of the QoS control register. See QoS Control Register and Table 3.2.

Usage constraints

You cannot increase the limits above either:

the configuration limits you set at design time
the CoreLink NIC-400 Network Interconnect limit of 32.

Configurations

Only available when you select outstanding transaction regulation in AMBA Designer.

Attributes

See Table 3.1.

Figure 3.2 shows the bit assignments.

Figure 3.2. max_ot Register bit assignments

Table 3.3 shows the bit assignments.

Table 3.3. max_ot Register bit assignments

Bits	Name	Function
[31:30]	-	Reserved. Do not modify. Read as zero.
[29:24]	ar_max_oti	Integer part of the maximum outstanding AR addresses.
[23:16]	ar_max_otf	Fractional part of the maximum outstanding AR addresses.
[15:14]	-	Reserved. Do not modify. Read as zero.
[13:8]	aw_max_oti	Integer part of the maximum outstanding AW addresses.
[7:0]	aw_max_otf	Fractional part of the maximum outstanding AW addresses.

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