Method for link bandwidth management

Abstract

A method for link bandwidth management between two devices in communication through a bus in a computer system. Whether a change condition of the bus having a link is activated is monitored. Change a bandwidth of the bus from a first bandwidth with a first width and a first speed to a target bandwidth with a second width and the first speed or with the first width and a second speed when the change condition of the bus is activated. The bus will operate at the target bandwidth without disabling the link or powering down the computer system if subsequent failure speed management and unreliable speed management have passed.

1 . A method for link bandwidth management between two devices in communication through a bandwidth-adjustable bus in a computer system, comprising:
 monitoring whether a change condition of said bus having a link is activated;   changing a bandwidth of said bus from a first bandwidth with a first width and a first speed to a target bandwidth with a second width and said first speed or with said first width and a second speed when said change condition of said bus is activated; and   causing said bus to operate at said target bandwidth without disabling said link or powering down said computer system.   
   
   
       2 . The method according to  claim 1 , wherein said bus is a PCI express bus. 
   
   
       3 . The method according to  claim 1 , wherein selectable widths of said link include 1-lane width, 2-lane width, 4-lane width, 8-lane width, 16-lane width, or 32-lane width and selectable speeds of said link include a generation 1 speed having a clock data rate of 2.5 GHz and a generation 2 speed having a clock data rate of 5 GHz. 
   
   
       4 . The method according to  claim 1 , wherein said two devices are a north bridge chip and a graphic chip. 
   
   
       5 . The method according to  claim 1 , further comprising if said bus has failed to operate at said target bandwidth, causing said bus to remain operating at said original width and speed and recording said target bandwidth as an unattainable bandwidth. 
   
   
       6 . The method according to  claim 1 , further comprising if said bus operates at said target bandwidth and said target bandwidth is unreliable, causing said bus to remain operating at said original width and speed and recording said target bandwidth as an unattainable bandwidth. 
   
   
       7 . The method according to  claim 1 , wherein said change condition includes a software-directed change, a hardware autonomous change, and an unreliable change. 
   
   
       8 . The method according to  claim 7 , wherein activation of said software-directed change includes:
 storing a required bandwidth data into a register when said computer system executes a software application; and   activating said software-directed change if said required bandwidth is different from said first bandwidth.   
   
   
       9 . The method according to  claim 7 , wherein activation of said hardware autonomous change includes:
 calculating a percentage of non-logic idle when a number of continuous logic idle symbols in one of said two devices exceeding a first programmable limit; and   activating said hardware autonomous change if said percentage of non-logic idle is greater than a second programmable value or lower than a third programmable value.   
   
   
       10 . The method according to  claim 9 , further comprising:
 changing said first bandwidth to said target bandwidth having said second width and said first speed if an option is set to a first status; and   changing said first bandwidth to said target bandwidth having said first width and said second speed if said option is set to a second status.   
   
   
       11 . The method according to  claim 7 , wherein activation of said unreliable change includes:
 activating said unreliable change if a translation layer packet has been resent exceeding a fourth programmable number of times by a transmitter in one of said two devices and still fails to be acknowledged by the other of said two devices; and   activating said unreliable change if a receiver gets a translation layer packet and a cycle redundancy check error case exceeding a fifth programmable number of times.   
   
   
       12 . The method according to  claim 11 , further comprising:
 changing said first bandwidth to said target bandwidth having said second width and said first speed if a speed unreliable option is set to a first status; and   changing said first bandwidth to said target bandwidth having said first width and said second speed if said speed unreliable option is set to a second status.