Hi Jens, On Fri, Feb 27, 2015 at 8:41 PM, Jens Thiele <[email protected]> wrote: > Julian Calaby <[email protected]> writes: > >> Hi Jens, > > Hi, > >> On Fri, Feb 27, 2015 at 1:41 AM, Jens Thiele <[email protected]> wrote: >>> Do you think it is reasonable to expect the display/touchscreen of two >>> Allwinner based tablets sold by the same name (including model number) >>> are identical, or do they use different displays / touchscreen elements >>> all the time? >> >> I think the answer is "It depends" >> >> I have two Allwinner SoC based tablets, one is a "generic" board that >> has been put into at least three different tablets I'm aware of. The >> FEX file and Android instance for it have configuration and drivers >> for at least three different models of touch screen. > > are those resistive touchscreens => sun4i-ts driver? > are the fex files available on > git://github.com/linux-sunxi/sunxi-boards.git ? (see also below)
They're all i2c touch screens. See https://github.com/linux-sunxi/sunxi-boards/blob/master/sys_config/a10/inet_3fbt.fex I'm planning to get the mainline kernel / u-boot running on it shortly and will probably end up with a DTS specific to the tablet I have, however if someone happens to add support for one of the other tablets with the same board we're going to have to figure out a solution for all the duplication. (The only thing in the FEX that has multiple options is the touch screen - it might get customised per tablet, but I doubt it, apart from the boot screens, some pre-installed apps and sticking the name of the tablet in the "About" section of Android, no tablet-specific customisation of the ROM appears to have happened.) >> The other is manufactured by HP and I believe that while the >> particular board is put into at least 2 different models, they're all >> slight variations on the same thing (different / cheaper LCD) and >> consequently should all have the same touch screen chip. > > The differences I see are with the resistive touchscreen panels / cover > themself / even the surface feels different ... hard to explain > those parts: > https://www.olimex.com/Products/OLinuXino/LCD/A13-TS7/ > https://www.olimex.com/Products/OLinuXino/LCD/A13-TS10/ My point is that we now have a product that can have two different resistive touch screens added to it. This makes things complicated =) >> I think the general consensus is that one can assume that all tablets >> with the same name and details will have the same touch screen. In >> your case, with development boards, that's less viable and we possibly >> should be using device tree overlays (or whatever they're called) to >> separate peripheral configuration (the LCD + touch screen board) from >> system configuration (the development board itself) but I'm hazy on >> the details. >> >> IMHO, you should write the patch to get the value from device tree and >> worry about the board configuration details when submitting that. > > Just wanted to start with this, but then had look at the fex files from > git://github.com/linux-sunxi/sunxi-boards.git > having "rtp_used = 1". > > They nearly all have the same rtp_para block: > > [rtp_para] > rtp_used = 1 > rtp_screen_size = 5 > rtp_regidity_level = 5 > rtp_press_threshold_enable = 0 > rtp_press_threshold = 0x1f40 > rtp_sensitive_level = 0xf > rtp_exchange_x_y_flag = 0 > > The exceptions are: > ./a10/iteaduino_plus_a10.fex > [rtp_para] > rtp_used = 1 > rtp_screen_size = 7 > rtp_regidity_level = 5 > rtp_press_threshold_enable = 1 > rtp_press_threshold = 0x1f40 > rtp_sensitive_level = 0xf > rtp_exchange_x_y_flag = 0 > > ./a13/ampe_a76.fex > [rtp_para] > rtp_used = 1 > rtp_screen_size = 7 > rtp_regidity_level = 5 > rtp_press_threshold_enable = 0 > rtp_press_threshold = 0x1f40 > rtp_sensitive_level = 0xf > rtp_exchange_x_y_flag = 0 > > But both use rtp_sensitive_level = 0xf, too. Now I am not sure, it is > really worth it. And I believe that they're all for tablets which have fixed touch screens. IMHO we should have access to all the parameters that can be configured per-device in the DTS. That we don't is a bug that arguably should be fixed. Again, I urge you to make that parameter available in device tree as it'll be useful for you in conjunction with device tree overlays. Thanks, -- Julian Calaby Email: [email protected] Profile: http://www.google.com/profiles/julian.calaby/ -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
