LG Dual-Sourcing panels again w/G4 - possible touchscreen issue correlation

[xdabbeb]

After receiving my G4 last week and digging into it, I found that LG is once again dual-sourcing (JDI and in-house LGD) panels for the G4, and that all most verifiable touchscreen issues I have recorded have been on JDI panel equipped devices (EDIT: Though the vast majority were JDI, there was at least one LGD with the same issue). The problem itself is EMI/noise related and is remedied by a solid path to ground (plugging it in, good contact with your hand, etc).

I have verified this with a few dozen phones so far, but more data would be helpful. If you're going to, however, please don't post if you just feel that your touchscreen isn't as responsive as you'd like (missed taps, etc). There's too much room for error there. To verify that your device has the issue, it is best to count the number of discreet touch events it can register both while unplugged and plugged-in/grounded. If your device has the issue, you will only get 5-6 before failure while unplugged and 10 while plugged-in. You can use the free app Display Tester from the play store to check.

As for determining which panel you have, the easiest way is to check your kernel message buffer immediately after boot using dmesg. If you're rooted you can do this on the device, if you aren't rooted you can use adb.

dmesg | grep -i panel

The oem will be in your kernel command line, panel name, etc.

NOTE: Though it appears that there is a hardware element to this issue, I do think it's possible that LG could fix it in the touch driver with a software update. I personally haven't updated to the firmware that was reported to fix this on my variant (vs98612a) as it was pulled, so I can't say firsthand.

 

[GalaxyFan88]

LG panel here. Just tested with display tester. While holding the phone in my hand it recognizes multiple fingers easily.
However if I lay down the G4 on whatever ground/table (it doesn't matter) it barely recognizes two fingers, the second one has to be pushed harder to get it recognized by the screen. Three fingers and it's game over. Really strange. So now I know why it was always difficult using the phone i.e. at work when I wanted to "passively" check whats going on. Most of my touches and swipes (even with one finger) were more prone to erratic behaviour while the pone was laying on my desk.

I am using LG's 6.0 MM by the way with S3V3n's rooted kernel and unlocked bootloader btw. Also there is a tempered glass protector on my screen.

Check the terminal log below for reference regarding my screen type (LGD).

[email protected]:/ $ su
[email protected]:/ # dmesg | grep -i panel
[ 0.000000 / 01-01 00:00:00.000][0] Kernel command line: sched_enable_hmp=1 sched_enable_power_aware=1 console=ttyHSL0,115200,n8 androidboot.console=ttyHSL0 user_debug=31 ehci-hcd.park=3 lpm_levels.sleep_disabled=1 androidboot.selinux=permissive msm_rtb.filter=0x37 androidboot.hardware=p1 lge.rev=rev_10 model.name=LG-H815 lge.sim_num=1 lge.battid=SW3800_VC0 lge.bootreason=Reboot_by_PowerKey maxcpus boot_cpus=0-5 kswitch cc_mode=0 androidboot.bl_unlock_complete=true androidboot.dlcomplete=0 gpt bootcable.type=NO_INIT androidboot.ddr_info=0x3b000206 fakebattery=disable lge.bootreasoncode=0x77665501 lge.hreset=off fips_allow_others=1 fips_panic=0 fips=0 androidboot.bootdevice=f9824900.sdhci androidboot.serialno=LGH8157479244e lge.signed_image=false lge.dsv_id=DW androidboot.baseband=msm mdss_mdp.panel=1:dsi:0:qcom,mdss_dsi_lgd_r69007_1440p_mipi0_cmd:1:qcom,mdss_dsi_lgd_r69007_1440p_mipi1_cmd
[ 0.766209 / 01-01 00:00:00.759][4] mdss_dsi_panel_init: Panel Name = LGD INCELL 1440p Dual 0 cmd mode dsi panel
[ 0.766220 / 01-01 00:00:00.759][4] lgd_qhd_command_mdss_dsi_panel_init: panel_type is LGD_INCELL_CMD_PANEL
[ 0.766229 / 01-01 00:00:00.759][4] panel_type is 2
[ 0.766364 / 01-01 00:00:00.759][4] mdss_dsi_panel_timing_from_dt: found new timing "qcom,mdss_dsi_lgd_r69007_1440p_mipi0_cmd" (ffffffc0c56a38a8)

 

[One Twelve]

After receiving my G4 last week and digging into it, I found that LG is once again dual-sourcing (JDI and in-house LGD) panels for the G4, and that all verifiable touchscreen issues I have recorded have been on JDI panel equipped devices.

It took just one reply to disprove that

The problem itself is EMI/noise related and is remedied by a solid path to ground (plugging it in, good contact with your hand, etc).

which will apply regardless of where the panel was sourced. A phone with a curve isn't really ideally suited to be operated on a flat surface anyway.

I've noted this tendency to point out where a component comes from here on the boards and this then gets extrapolated into something bad. i would not interpret a non-oem panel as a problem whatsoever.

components are sourced when required from suppliers that can build to scale. They are equivalent for all intents and purposes.

it should not make a bit of difference whether the panel is LG or JDI. If it does then it just means you 'may' have a defective panel. This can happen with either source.

 

[konradsa]

I think you may be on to something. I got the JDI panel, and I noticed that if I use a touch tester app, it can only register 5 touches successfully when unplugged. The 6th touch causes it to lose all touch points. However, when it's plugged into power, it can register 10 touches without a problem.

Not that I need more than 5 touch points, but is this normal behavior for a digitizer to do that? Looks to me like this is something that could be tweaked in the driver. Would be interesting to know by someone with Verizon software 12A (I am on 11A) if they notice the same issue that their device only registers 5 touches max, or if that is something that has been addressed. I am really getting ticked off by Verizon peddling around and not being able to provide the update every other G4 user already has received. At this point, I am hoping xdabbeb's efforts of coming up with a fix for the 11A version bear some fruits.

 

[xdabbeb]

It took just one reply to disprove that

Actually, no...given the individual's report of not even being able to register 2 touches that sounds more like a hardware failure than what is being investigated here.

which will apply regardless of where the panel was sourced. A phone with a curve isn't really ideally suited to be operated on a flat surface anyway.

I don't believe I mentioned laying it flat on a table as part of this test, but, yes, a curved phone isn't suited to that.

I've noted this tendency to point out where a component comes from here on the boards and this then gets extrapolated into something bad. i would not interpret a non-oem panel as a problem whatsoever.

components are sourced when required from suppliers that can build to scale. They are equivalent for all intents and purposes.

it should not make a bit of difference whether the panel is LG or JDI. If it does then it just means you 'may' have a defective panel. This can happen with either source.

I was actually quite careful in making no judgment in this regard. The words 'bad' and 'defective' were only used by you, actually. I personally don't care what panel was/is used and even stated that given the nature of the problem I feel a software fix is certainly possible.

Though there will be a tendency with any device that has a large scale issue such as this to (sometimes blindly) grasp at finding the cause, the purpose of this was to gather more information, not incite a witch hunt. I personally gathered over 3 dozen logs/reports that supported this before posting, and felt that this was the best way to get more.. I have no horse in this otherwise. I have noted tendencies of contrarianism and gross generalization, but it's the Internet...You're going to get that






@konradsa the qfuse situation makes investigating that more problematic, but that's precisely what I'm looking into next.

 

[konradsa]

@konradsa the qfuse situation makes investigating that more problematic, but that's precisely what I'm looking into next.

Thanks, appreciate your efforts and looking forward to your results.

 

[random_word]

I think you may be on to something. I got the JDI panel, and I noticed that if I use a touch tester app, it can only register 5 touches successfully when unplugged. The 6th touch causes it to lose all touch points. However, when it's plugged into power, it can register 10 touches without a problem.

Same problem with LGD panel.

 

[xdabbeb]

Same problem with LGD panel.

If it was exactly the same then that settles it. Thanks for the report. Closing the thread.