[Nexus 7 General] aristoc:
Hi guys, bit of an update from yesterday and some clarification.

First of all, Tesco were pretty great about the exchange, given that my nexus was still within its 10 day 'returns' period - they swapped it out in-store for a (to my delight) a C8OK which so far has nothing wrong with it.

Now, on the nature of the actual fault discussed in this thread. I'm aware that there is another issue doing the rounds on 7's which involves the tegra prism jobbo. This causes washed out colours with little contrast after viewing HD video or other such full screen 'stuff' and can be solved either via script, app, or directly disabling prism in the /sys tree.

This problem is distinct from that experienced by myself and others above.

The washed out screen after playback issue is solved almost immediately upon disabling prism. It should also be noted that as far as I can tell, the prism issue is in no way as problematic or indeed noticeable as our complete and utter sun-vomit condition. A key feature of this wash-out being that it is not effected in the least by the disabling of prism. I have played around in that /sys tree quite a lot and no enabling or disabling of anything yielded any positive effect.

Our problem is also non-dependent on video playback. I hadn't watched a single video on my nexus when mine suddenly became white-washed yesterday morning. And in some strange paradoxical behavior in contrast to the prism bug the white-washing gets worse if the device is turned off and then on for extended periods of time. When I got to the store today for a replacement I didn't even have to explain what was happening, I said 'turn on the device and you'll see what's wrong'. Sure enough, having been powered down for a few hours, the entire screen was as white as snow.

Another distinct 'feature' of this problem from that of the prism bug is that our white washing is accompanied by some pretty atrocious image retention. I'm not talking a faint shadow here - I'm talking being able to read the address bar of chrome having closed the app and returned to the home screen. Or being able to see emails in readable clarity from the home screen having exited the mail app.

But the strongest distinction between this and the prism bug, I feel, is reproducibility; or lack thereof. Of those reporting this problem, the vast majority found that it happened 'out of the blue' after days, or weeks of use. No change in environment or use of the tablet, no new application installed or sudden marathon of videos. To my knowledge no documented sequence of events on the tablet renders it permanently white-washed in this manner. It 'just happens'; and in this way is not reproducible in the slightest for users who don't already have the problem. The prism bug, on the other hand, is easily reproducible by (i think?) any nexus user simply by watching HD video for an extended time and then returning to the home screen. It is this distinction in particular that, to me, suggests that the problem is hardware related.

Software, no matter the language or the architecture, is not some magical goo that does what it wants when it feels like. Computers of any kind will do as they are told, and if undesirable or paradoxical behavior is exhibited, then it because of some oversight by the programmer. The program is doing everything it has been instructed to do, and will continue to do so ad infinitum if instructed. The 'bug' in this way is reproducible, provided the user follows the exact same sequence of events as those which produced the bug prior. I would suggest that reproducibility in this manner is necessary in the identification of a software bug. The prism bug is indeed reproducible in this manner, but the white-wash bug I and others have experienced in this thread is not. In fact for the majority of users it occurred after days of normal repetitive use.

The reason for my rant is that I'd rather not see this problem grouped in with the prism bug and waved aside as some trivial, known matter. It basically renders the nexus unusable in some circumstances and in my view is quite probably a hardware issue which is not going to be fixed anytime soon.

You might think my logic flawed, and if so please do provide a rebuttal. The last thing I want to do is spread misinformation. But again I will reiterate; this is a non-reproducible fault which behaves in markedly different ways to the known prism bug. In fact it is identical to the fault found on the I/O tablets issued earlier in the year.

Many thanks for reading my rant! lol. Excuse my poor writing as well, i'm in the middle of a horrible hay fever attack, lol.

John