On Sun, Dec 10, 2017 at 11:10 PM, David Lechner david@lechnology.com wrote:
This adds a new device tree binding for Sitronix ST7735R display panels, such as the Adafruit 1.8" TFT.
Signed-off-by: David Lechner david@lechnology.com Acked-by: Rob Herring robh@kernel.org
(...)
Limor brought up an interesting point in an off-list discussion. The same controller can be wired to the same LCD in different ways. This is evident in the fbftf drivers in staging. There is an "adafruit18" and an "adafruit18_green" in fbftf_devices.c where apparently, two otherwise identical displays were wired slightly differently at the factory so that on one, the on-board GRAM word 0 does not correspond to pixel 0,0 on the LCD. It requires a special offset to the GRAM starting address in order to have the image displayed correctly.
Additionally, fbtft supports a SainSmart 1.8" TFT [3] that uses the same controller, but it appears that these have different gamma curves (perhaps they use different LCDs?). The available pins are exactly the same as the Adafruit display though.
This discussion came up in relation to the Ilitek ILI9322 bindings, here are some links: https://marc.info/?l=dri-devel&m=150300267811979&w=2 https://marc.info/?l=devicetree&m=150438702909506&w=2 https://marc.info/?l=dri-devel&m=150628542603682&w=2
The last mail from Rob clearly indicates that he doesn't like this kind of open-ended configuration data stashed up in the DTS.
There was a binding acked recently for the LCD on a D-Link DIR-685 Wireless N Storage Router [8]. This uses the compound compatible string of "dlink, dir-685-panel", "ilitek,ili9322". If we want to try to keep things consistent, perhaps I should be adopting this pattern as well?
I think so.
And perhaps it would be better to use the better known vendor name instead of the obscure vendors from the datasheets that I have found? For example, "adafruit,618" "sitronix,st7735r" instead of "jianda,jd-t18003-t01"?
I don't know this, just that it should be:
"vendor,specific-system-config", "vendor,ip-part";
Yours, Linus Walleij