Low-latency touch feedback

1. An arrangement, comprising:

a touch screen controller comprising circuitry and communicatively coupled with a touch sensor, a display screen, and a central processing unit (CPU), wherein the touch screen controller is configured to:

receive, while the CPU is in a sleep state and while applying a predefined first gamma curve having a first curvature to the display screen, a first touch input from the touch sensor; and

change, based on the first touch input and while the CPU remains in the sleep state, a visual characteristic of the display screen to visually indicate that the first touch input satisfies one or more predetermined touch criteria, wherein changing the visual characteristic of the display screen comprises:

determining, based on at least one touch characteristic of the first touch input, a second curvature different than the first curvature; and

applying a second gamma curve having the second curvature to the display screen.

2. The arrangement of claim 1 , wherein the touch screen controller is included in a display device integrated circuit (DDI), and wherein changing the visual characteristic of the display screen comprises changing a parameter associated with the DDI.

3. The arrangement of claim 1 , wherein changing the visual characteristic of the display screen further comprises displaying a first predetermined image on the display screen.

4. The arrangement of claim 3 , wherein the first predetermined image comprises a lock screen image.

5. The arrangement of claim 1 , wherein the touch screen controller is further configured to:

receive, while the CPU remains in the sleep state, a second touch input from the touch sensor; and

wake, upon determining the second touch input corresponds to a predetermined unlock gesture and is contiguous in time with the first touch input, the CPU from the sleep state.

6. The arrangement of claim 1 , wherein changing the visual characteristic of the display screen is based on a duration of the first touch input.

7. The arrangement of claim 1 , wherein changing the visual characteristic of the display screen is based on an input pressure associated with the first touch input.

8. The arrangement of claim 1 , wherein changing the visual characteristic of the display screen is based on a position of the first touch input.

9. The arrangement of claim 1 , wherein the first touch input is provided by an input object, wherein the at least one touch characteristic of the first touch input comprises a proximity of the input object to a surface associated with the touch sensor.

10. The arrangement of claim 9 , wherein determining a second curvature comprises:

increasing from the first curvature when the proximity of the input object increases, wherein the second gamma curve comprises a boosted gamma curve.

11. The arrangement of claim 10 , wherein the touch screen controller is further configured to:

determine a third curvature different than the second curvature when the proximity of the input object decreases, wherein determining the third curvature comprises decreasing from the second curvature; and

apply a third gamma curve having the third curvature to the display screen.

12. A method of input sensing using a touch screen controller coupled with a touch sensor, a display screen, and a central processing unit (CPU), the method comprising:

receiving, while the CPU is in a sleep state and while applying a predefined first gamma curve having a first curvature to the display screen, a first touch input from the touch sensor; and

changing, based on the first touch input and while the CPU remains in the sleep state, a visual characteristic of the display screen to visually indicate that the first touch input satisfies one or more predetermined touch criteria, wherein changing the visual characteristic of the display screen comprises:

determining, based on at least one touch characteristic of the first touch input, a second curvature different than the first curvature; and

applying a second gamma curve having the second curvature to the display screen.

13. The method of claim 12 , wherein the touch screen controller is included in a display device integrated circuit (DDI), and wherein changing the visual characteristic of the display screen comprises changing a parameter associated with the DDI.

14. The method of claim 12 , wherein changing the visual characteristic of the display screen further comprises displaying a first predetermined image on the display screen.

15. The method of claim 14 , wherein the first predetermined image comprises a lock screen image.

16. The method of claim 12 , further comprising:

receiving, while the CPU remains in the sleep state, a second touch input from the touch sensor; and

waking, upon determining the second touch input corresponds to a predetermined unlock gesture and is contiguous in time with the first touch input, the CPU from the sleep state.

17. The method of claim 12 , wherein changing the visual characteristic of the display screen is based on a duration of the first touch input.

18. The method of claim 12 , wherein changing the visual characteristic of the display screen is based on an input pressure associated with the first touch input.

19. A touch screen controller for a touch screen device having a touch sensor and a display screen, the touch screen controller comprising:

a sensor module comprising circuitry and coupled with a central processing unit (CPU) and with the touch sensor, the sensor module configured to:

receive, while the CPU is in a sleep state, a first touch input from the touch sensor; and

determine at least one touch characteristic of the first touch input; and

a display driver module coupled with the sensor module and with the display screen, the display driver module configured to:

apply a predefined first gamma curve having a first curvature to the display screen, wherein the first touch input is received while applying the first predefined gamma curve;

change, based on the first touch input and while the CPU remains in the sleep state, a visual characteristic of the display screen to visually indicate that the first touch input satisfies one or more predetermined touch criteria, wherein changing the visual characteristic of the display screen comprises:

determining, based on the at least one touch characteristic of the first touch input, a second curvature different than the first curvature; and

applying a second gamma curve having the second curvature to the display screen.

20. The touch screen controller of claim 19 , wherein changing the visual characteristic of the display screen further comprises displaying a first predetermined image on the display screen.