1. TP focus areas and checklists
   First of all, the internal checklist of TP in the appendix shows that all the contents in the column are common problems and serious problems，As follows：
   Power on / off sequence
   

   Operating Voltage
   TP ic and manufacturer ID(Module ID)
   Check I2C SCLSet frequency
   
   
   
   Factory test items (raw data / short circuit / marking test)
   
   TP Interrupt frequency
   
   TP Reporting rate
   
   tp Accuracy
   
   tp Sensitivity
   
   Gravity test
   
   Suspension test (such as putting the device on a pillow or holding it in hand, touching it with a mobile phone)
   
   There will be no false positives
   
   Charger interference test
   
   Double Tap，Power consumption increment

FW Upgrade process confirmation
1）It will not be upgraded repeatedly
2）Different module version numbers cannot be included in a range
3）Wrong burning FW, can't force upgrade, use default
4）pushThe lower version will not be upgraded
FW upgrade repair: upgrade process, forced power off, after boot to be able to upgrade normally OK
Quick click TP, large area touch test
Back, home, and menu keys are used for quick test
Two finger horizontal / vertical stroke (ghost point),
Disconnection Test
Gesture support
boot the phone with no TP（Remove TP to test whether the mobile phone can be turned on）
boot in META mode

Daily waterproof test


2.Analysis diary of each problem
Each need to observe the hardware diagram and other aspects are not specifically described here.

TP ic and manufacturer ID(Module ID)
It is necessary to confirm the IC and operator ID of TP, especially in the case of multi supplier and common baseline development.
The IC ID and module ID of TP are the necessary conditions for firmware upgrade. This function determines the specific mobile phone by judging the IC and module ID, so as to load the driver correctly and upgrade firmware.

Check I2C SCL setting frequency
I think the HW check will be faster and easier. Under normal circumstances, the working voltage and power on / off time sequence of the item are detected by HW.

Mini test items (raw data / short circuit / scribing test)
This item is mainly used for factory detection. Rawdata is the original data of TP in factory detection. From the first detection, we can distinguish whether there is any abnormality in the screen hardware (for details, please refer to "abnormal demand analysis and implementation of CTP monomer in production line detection").Rawdata will have an open / short test. After the overall test is completed, a data will be saved (generally in sdcard /, which can be found in the driver).Similarly, the driver will register a node to provide the mmitest of the upper layer as an interface for the upper layer to read data (the factory will read from MMI, if there is a problem with this item, the factory production will be affected).Similarly, MMI also needs the upper rawdata.java to cooperate with the work, and FAE also needs to provide ini card control file to cooperate with the test. So far, this item can passSimilarly, in MMI, firmware selects the interface that also needs to provide firmware information to the upper layer. Specifically, it is modified in firmware.java and sysclass.java in MMI.

TP report rate, sensitivity
The subjective test project needs to analyze with Val and SPM, and wait for the customer's verification feedback to decide what level to modify. These two modifications are in firmware. FAE processing is required.

Suspension test, quick click TP, large area touch test, water mist test
For example, if you press a number in the dialing interface for a long time, the situation of "the number has been repeatedly clicked" will not appear in the dialing interface, and the modification is also in firmware.The water mist test is the water mist test of anti perspiration prescription, which depends on the quality of TP itself. The high-end TP can contact a large area of water without abnormal influence. The low-end TP, such as pixi4-4.5 VF MSG, can only achieve water mist and perspiration, and large water droplets will cause problems such as random reporting points.

False alarm point, jump point, disconnection and other subjective conditions
It is necessary to test all the screens after opening the point reporting function to make sure that all the screens can report points normally. This problem is also blocked in firmware.

The causes of touch screen (TP) jumping can be divided into five categories
(1) Touch screen hardware channel damaged  
(2)Touch screen firmware version too low
(3) Abnormal working voltage of touch screen
(4) Radio frequency interference  
(5)Touch screen calibration error

The hardware channel is damaged
1.Phenomenon：
       Click on a certain area of TP, there is no response, but the area around is sensed, resulting in a touch event
2.Problem analysis：
       The sensing area of TP is composed of a number of sensing channels. If some sensing channels are broken, TP can not sense the change of electric field when clicking on the area, so there is no response when clicking on the area, but the adjacent normal channels will sense the change of electric field, so there will be a touch event in that area.The feeling is that you touch this area, but another area responds
3.Root cause：
       TP hardware channel is damaged
4.Improvement measures：
       Replace the hardware

TP firmware version is too low
1.Phenomenon：
       TP can be used normally, but the press area and the response area are mirror images. For example, press the left area to respond to the right, press the right area to respond to the left
2.Problem analysis：
       TP local area can be used, but it is not accurate to press down, but the interrupt is normal and the position of the reported point is reversed. This phenomenon may be caused by the TP firmware is too old and does not match the current driver
3. root cause：
       TP firmware mismatch
4.Improvement measures：
       Upgrade TP firmware
 
Abnormal TP supply voltage
1.Phenomenon：
       TP's irregular jumping
2.Problem analysis：
       The irregular jump of TP indicates that TP itself is not working normally. When the power supply of TP is less than its normal working voltage, this phenomenon will be caused
3.Root cause：
       Abnormal TP power supply
4.Improvement measures：
       If the TP power supply voltage is modified to make it normal, the LDO power supply may need to be modified, and the hardware may need to be modified 

Radio frequency interference
1.Phenomenon：
      When dialing to make a call, after the number is dialed out, the screen appears the phenomenon of button skipping
2.Problem analysis：
      The phenomenon of disorderly jump appears when calling, which indicates that there is interference when calling. After measuring the working voltage of TP, it is found that the working voltage of TP fluctuates up and down
3.Root cause：
      TP voltage fluctuation caused by telephone call
4.Improvement measures：
       Adjust TP working voltage to make it in normal working range
 
TP calibration abnormal
1.Phenomenon：
       After a large area of pressing TP, the call will be answered, and the touch screen will be invalid. You need to press the power key twice to unlock
2.Problem analysis：
      After a large area of TP is pressed, TP may be calibrated. At this time, the threshold value of TP touch response changes, which is the threshold value when the finger is pressed. When a call is answered, after the finger is pressed, TP judges that there is no touch event according to the previous threshold value, so there is no response；When you press the power key to sleep and wake up, the TP will calibrate and return to the normal state, so it can be used
3.Root cause：
      After touching TP in a large area, unnecessary calibration occurs, which makes TP reference environment change and leads to incorrect judgment of TP during normal touch
4.Improvement measures：
       TP calibration algorithm is optimized to avoid unnecessary calibration, or the interval time is calibrated according to the normal reference value

Charger interference test
The interference of the model is likely to be the problem of the frequency band. Our company will generally match the chargers of specific manufacturers or those with high market share. Some low-end chargers do not match, so there may be some interference that can not be avoided. The specific situation is analyzed. If it is necessary to modify this aspect, the specific situation should be determined with HW and FAE.

Double Tap
VDF high-end opportunities have this demand. It is also necessary to generate interruption after double-click, sensor reports events such as too close distance, and the upper layer closes the screen. At this time, TP needs to re-enter gesture waiting mode. When dealing with this demand, we should also pay attention to the negative effects brought by this function, such as the problems that have already appeared, such as unable to enter sleep mode after opening double tap, or TP failure for a short time after double-click wake-up.

FW upgrade process confirmation
This is a serious piece of logic. Under normal circumstances, this logic is provided to our company after being modified by the manufacturer. However, it does not rule out that there will be omissions in the rough version, especially in the development stage of new projects, so this is a problem that must be checked.To determine whether the firmware judgment process is normal, first check whether the existing firmware is complete, and then judge whether it is based on the IC and module ID of TP, and whether this ID meets the requirements of the project. Generally, you don't mind optimizing and modifying the process independently. If there is any modification, please double check.

Firmware power off protection mechanism
Firmware upgrade protection mechanism, in the process of firmware upgrade power off, to ensure that the boot time can continue the last upgrade. In the above case, when the power is off, all the registers of firmware will be cleared, so you can't read the firmware version and all kinds of ID information in the mobile phone when the power is on. At this time, you need to read the last data from the boot, get the ID and version again, and then continue to complete the upgrade function.The logic of this block is complex and important, so we need to be familiar with it.

Back, home, and menu keys are used for quick test
Confirm that there is no problem with the three virtual keys. In addition to reporting points in the driver, the three virtual keys also report events or coordinates. At the same time, the upper layer also has a mapping file to control the function of each key.The mapping value and the reported value in the driver need to match.

Two finger horizontal / vertical stroke (ghost point)
When checking this item, first of all, you need to know whether the screen is self-contained or mutual tolerant. At present, high-end computers in the market all use mutual tolerant screen, which has great advantages in supporting reporting points. However, due to the hardware design and cost, the self-contained screen can only support the mode of false two points, and there will be ghost points in the restricted area, which cannot be optimized.For details, please refer to the defects in the overview of self contained screen design given by MSG.

3.Other
GPIO setting and delay
For TP correlation, there are two other points to be noted. One is that when GPIO is reset, delay is necessary, but the minimum delay needs to be determined with FAE. For example, when GPIO is pulled down and then up after reset, it needs to wait for 200ms on the low level before it can continue to operate.Second, we need to pay attention to the input or output of the GPIO port. If there is a problem with the amount of hardware, it needs to be corrected. GPIO reset is usually pulled high by default. To do a reset, we need to pull low and then pull high. The delay in the middle is 20ms, but after the reset is completed, we need to have 200ms delay, because the GPIO pin is not stable after pulling high, The operation in this state will cause problems such as reporting wrong data. 200ms is to stabilize the GPIO state, and 20ms is to wait for the effective time of the ground level. If it is not added, the whole reset will be invalid. For TP, the direction of GPIO reset (output / input) is output. Gpio_ set_ Value () is to set the pull up or pull down level without modifying the direction (the direction is set at the earliest), GPIO_ dirction_ Output / input () can set the direction in the case of setting up or down.

Input report event
The term "contact" is used to describe tools that directly contact surfaces, fingers, pens or rubbers, and can be classified as contact.Under normal circumstances, the driver is the reported coordinate rather than the event (three virtual keys may be defined separately as events).There are two input methods for reporting, one is anonymous reporting, the other is slot reporting (BTN is required for reporting, at least the first method is required for reporting)
ABS_MT_TOUCH_MAJOR
The length of the contact spindle, which should be given in surface units.If the surface has X-Y resolution,
ABS_MT_TOUCH_MAJOR
The largest possible value is sqrt (x ^ 2 + y ^ 2), which is diagonal.
ABS_MT_TOUCH_MINOR
The length of the minor axis of the contact surface, in surface units.If the contact surface is circular, this event can be ignored.
ABS_MT_WIDTH_MAJOR
The length of the long axis of the contact tool, in surface units.This should be understood as the size of the tool itself.The direction of the contact surface is the same as the corresponding tool assumption.
ABS_MT_WIDTH_MINOR
The short axis length of the contact tool, in surface units.If it is circular, ignore.
These four values can be used to derive additional information about contact.
ABS_MT_TOUCH_MAJOR/ABS_ MT_ WIDTH_ Major is close to the concept of pressure.Fingers and palms have different characteristic widths.
ABS_MT_PRESSURE

The pressure can be any unit in the contact area.It may be used for corresponding touch and width, for pressure based devices or any spatial signal density distribution devices.
ABS_MT_ORIENTATION
The direction of the ellipse.This value should describe a signed clockwise rotation around the center of the contact.The range of signed values is arbitrary, but for fingers along the Y axis of the surface, it should return 0, negative when the finger turns to the left, positive when the finger turns to the right.Returns the maximum value of the value when it is completely along the x-axis.If the contact object is circular or the kernel driver does not provide this information, the direction can be ignoredIf the device can distinguish two dimensions, but can't guarantee any value, it may be partially supported.At this time, ABS_ MT_ The value range of orientation should be [0, 1] [4]
ABS_MT_POSITION_X
The X surface coordinate of the center of the contact ellipse.
ABS_MT_POSITION_Y
Y surface coordinate of the contact ellipse center.
ABS_MT_TOOL_TYPE
Type of contact tool.Many kernel drivers don't distinguish between different tool types, such as fingers and pens.In this case, the event should be ignored.The protocol currently supports Mt_ TOOL_ Finger and MT_ TOOL_ PEN。[ 2].
ABS_MT_BLOB_ID
BLOB_ ID weaves multiple packets into a set of arbitrarily shaped contacts.This is a low-level anonymous group and should not be confused with a high-level tracking ID. [5].Most kernel drivers do not have the ability to blob and can safely ignore this event.
ABS_MT_TRACKING_ID
TRACKING_ ID identifies an initial contact throughout the life cycle. [5] There are very few devices supporting this event, so this event is usually ignored.
ScreenPinning
This is a special requirement of VDF on Android L, which is used to lock the screen. You can't use the home and back virtual keys to exit the program directly, which is equivalent to a child lock.The requirement of this function in the bottom layer of TP is to report back and menu keys at the same time. If it is not handled, each virtual key will report down / up events continuously, which is equivalent to two fingers clicking the button quickly. In fact, this is not up to the standard. This function requires back and menu to report down at the same time and stably, and can not be unlocked with up eventsThis function needs to pay attention to whether it will be affected by USB interface.For this function, if you modify it in the driver, you need to modify the point reporting logic (such as MSG).There are also solutions to deal with it in firmware, such as ft.
TP simulates P-Sensor function
In some low-end projects, sensor will not be configured due to cost and other reasons, but in order to avoid false touch in the process of calling, TP will be used to simulate P-Sensor.The overall thinking is as follows: the overall TP is adjusted higher at the expense of sensitivity. During a call, if the TP receives an interrupt when there is a touch and the touch area belongs to the upper part of the screen, then the screen will go out and go to sleep. When the TP is not touched when it leaves, it will be judged to be far away and the screen will light up.This function will be designed to call flow, TP interrupt flow, suspend and resume. This function will also cause other problems that need to be dealt with. For example, if headphones are used in the process of a call, or due to fraud restrictions, the TP level is low, and there will be abnormal situations under heavy pressure.

TP FW upgrade logic / FW upgrade interrupt reply mechanism

Normally, the upgrade of touchpanel is carried out in the probe function. Generally, a new work queue will be created in the upgrade function to make it independent of the main process and become a special sub process for firmware upgrade.Then it will judge and screen before upgrading according to the logic of upgrading.    It mainly determines whether the FW in the mobile phone and the FW read from the. H / bin file are the same IC / module manufacturer.Then judge whether the version number of the corresponding FW meets the requirements, and upgrade after meeting the above requirements.The upgrade process lasts about 10 seconds, and there will be no logs in the middle.According to the logic of upgrade, the special requirement of Shanghai site is that there is no need to judge the version number to force upgrade in MMI version.This verifies that there are exceptions during multiple upgrades.   Since FW takes a long time to upgrade, it is necessary to ensure that it can self repair in case of exceptionIf it is interrupted by power failure during the upgrade process, the FW version number and IC manufacturer number in the mobile phone will be both 0x00 (because power failure will cause all corresponding registers to be 0x00).When the boot process reads such a version number, it will use the power-off protection mechanism to read the previous version number from the boot to upgrade.    During the normal upgrade, the operation of registers is to write while erasing, so there is no case that the information cannot be read from boot.But there are two special upgrade methods:
1.Upgrade with apk；
2.Upgrade by writing. Bin file directly to node (FT retains the function)
   These two ways are to erase all the register information in the mobile phone before writing it.Therefore, if the upgrade process is interrupted, it is likely to result in an exception that can not be recovered.