How Devices Use 'Credits' to Manage Data Flow to Storage

This patent describes a system where a main device and a storage device use a 'credit' system to efficiently manage the flow of commands and responses, preventing either side from being overwhelmed with too much data.

What it covers

This patent details an electronic device, like a smartphone, where a main 'host device' communicates with a 'storage device' using a credit-based system. The host device has processing circuitry that handles a 'submission queue' (SQ) for commands going to storage and a 'completion queue' (CQ) for responses coming back (Claim 1). To prevent overloading the storage, the host stores a 'host command credit' indicating how many commands the storage can handle. Similarly, the host uses a 'host response credit' to show how many responses it can receive. The storage device also maintains its own credits (Claim 3) to signal its capacity to the host. For example, the host checks the storage's empty command slots using its 'host command credit' before sending a command (Claim 2), ensuring the storage has space.

What it doesn't cover

• —Does not cover data transfer systems that do not use a 'credit' mechanism for flow control between host and storage.
• —Does not cover systems where command and response queues are managed without explicit 'host command registers' and 'host response registers' as described in Claim 1.
• —Does not cover communication protocols between host and storage that are not based on the Universal Flash Storage (UFS) standard, as implied by the abstract.
• —Does not cover systems where the host device does not process both a submission queue (SQ) for commands and a completion queue (CQ) for responses.
• —Does not cover storage devices that do not include a 'storage response register' or 'storage command register' to manage their own credit counts (Claim 3).

The clever bit

The clever part is the bidirectional 'credit' system. Both the host and storage device actively track and communicate their capacity for incoming data (commands or responses) using dedicated registers, allowing for dynamic and efficient flow control that prevents either side from being overwhelmed.

Why it matters

This patent addresses a fundamental challenge in modern electronics: ensuring fast and reliable communication between a device's main processor and its storage, especially in high-performance scenarios. By using a credit system, devices can prevent bottlenecks and data loss, leading to smoother operation and faster performance. This is particularly important for Universal Flash Storage (UFS) devices, which are common in smartphones and other portable electronics, where speed and efficiency are critical.

Real-world examples

• 1.Modern smartphones using UFS storage
• 2.Tablets with high-speed flash memory
• 3.Embedded systems requiring efficient data transfer to flash storage
• 4.Automotive infotainment systems with UFS memory