Abstract: Methods and apparatus for packing received Serial Attached SCSI (SAS) frames in buffers for transmission to a host system memory. SAS frames are received from another SAS device and stored in a frame buffer memory. User data in the received frames has appended SCSI Data Integrity Fields (DIF information) to enhance reliability. Features and aspects hereof use the DIF information to validate the user data and then strip the DIF information to densely pack the validated user data in a DMA staging buffer for transmission to a host's system buffer memory using DMA features of the SAS device. The DMA circuit is programmed and started when the staging buffer is filled to at least a threshold amount of data to thereby improve efficacy of the DMA transfer performance. Other criteria may also be employed to determine when to start the DMA circuit.

Abstract: Methods and structures for validating tag information received in SAS frames by any of a plurality of ports comprising a SAS wide port. Each port may have a dedicated transport layer processing element. A tag information table is shared by all of the one or more transport layer processing elements. The tag information table is used to store information regarding a particular tag value being valid for use with a particular device and is updated when the particular tag value is no longer valid for use with the particular device. The information is initially stored in response to transmission of a frame that first uses the particular tag value with the particular device. The tag information table is updated to indicate the particular tag value is no longer valid upon receipt of an appropriate SAS frame or by a processing element external to the one or more transport layer processing elements.

Abstract: Methods and structures for validating tag information received in SAS frames by any of a plurality of ports comprising a SAS wide port. Each port may have a dedicated transport layer processing element. A tag information table is shared by all of the one or more transport layer processing elements. The tag information table is used to store information regarding a particular tag value being valid for use with a particular device and is updated when the particular tag value is no longer valid for use with the particular device. The information is initially stored in response to transmission of a frame that first uses the particular tag value with the particular device. The tag information table is updated to indicate the particular tag value is no longer valid upon receipt of an appropriate SAS frame or by a processing element external to the one or more transport layer processing elements.

Abstract: Methods and apparatus for packing received Serial Attached SCSI (SAS) frames in buffers for transmission to a host system memory. SAS frames are received from another SAS device and stored in a frame buffer memory. User data in the received frames has appended SCSI Data Integrity Fields (DIF information) to enhance reliability. Features and aspects hereof use the DIF information to validate the user data and then strip the DIF information to densely pack the validated user data in a DMA staging buffer for transmission to a host's system buffer memory using DMA features of the SAS device. The DMA circuit is programmed and started when the staging buffer is filled to at least a threshold amount of data to thereby improve efficacy of the DMA transfer performance. Other criteria may also be employed to determine when to start the DMA circuit.