US 2006/0041691 A1 · Circuit and method to provide configuration of serial ATA queue depth versus number of devices

Abstract

Disclosed is a system using a SAS host controller and SAS expanders to control multiple SATA end devices where the memory contained on the SAS host controller is fixed to ease the cost and power consumption of the SAS host controller device, but where there is an expanded ability to support additional SATA end devices by configuring the allowed native command queue depth to be smaller for each SATA end device, thus allowing more SATA end devices to be supported by a single SAS host controller. An embodiment of the invention has three possible preset configuration states: thirty-two SATA end devices with a native command queue depth of thirty-two; sixty-four SATA end devices with a native command queue depth of sixteen; and one-hundred-twenty-eight SATA end devices with a native command queue depth of eight.

Claims4

Dependent claims

A method of using a SAS host controller having a predetermined amount of memory and predetermined computational resources to manage a plurality of SATA end devices comprising:

creating a plurality of preset configurations that establish the number of said SATA end devices supported by said SAS host controller and a native command queue depth of each of said SATA end devices so that said predetermined amount of memory in said SAS host controller and said predetermined computational resources of said SAS host controller are sufficient to allow said SAS host controller to control said plurality of SATA end devices;
and
selecting a preset configuration from said plurality of preset configurations in accordance with a desired number of said plurality of SATA end devices that are connected to said SAS host controller.

A SAS host controller device that controls a plurality of SATA end devices comprising:

a multiplexer that generates a tag table index which is the concatenation of a device identification number identifying a SATA end device, and a native command queue command identifier representing a native command currently queued in the native command queue of said SATA end device, in accordance with a selected configuration state provided by a configuration register so as to generate a concatenated tag table index signal;
a native command pointer array that selects a native command pointer that is stored in said native command pointer array in response to said concatenated tag table index signal so as to deliver said native command pointer to said SAS host controller device;
a multiplexer that generates a SActive RAM table index which is a subset of said device identification number identifying said SATA end device, said subset of said device identification number determined in accordance with said selected configuration state provided by said configuration register so as to generate a SActive RAM table index signal;
an array of SActive values that selects a chosen SActive value that is stored in said array of SActive values in response to said SActive RAM table index signal, wherein each SActive value of said array of SActive values is a block of native command queue status bits;
and
a logic algorithm that generates an adjusted SActive value which is a subset of the bits of said chosen SActive value, said subset of the bits of said chosen SActive value determined in accordance with said device identification number and said configuration state provided by said configuration register, wherein said subset of bits of said chosen SActive value is shifted to the least significant bits of said chosen SActive value and the remaining bits of said chosen SActive value are given zero values so as to deliver said adjusted SActive value to said SAS host controller device.

3 more elements

Dependencies are inferred from the claim text.

Circuit and method to provide configuration of serial ATA queue depth versus number of devices

Life of this patent

Circuit and method to provide configuration of serial ATA queue depth versus number of devices

Life of this patent

Abstract

Claims4