# \[PATCH\] atmel\_lcdfb: support 16bit BGR:565 mode, remove unsupported 15bit modes

- From: Peter Korsgaard \<jacmet@sunsite.dk\>
- Date: 2012-01-10 16:42:36 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2012/01/8594310
- Thread: https://ratatoskr.run/linux-arm-kernel/2012/01/8594310/t.md

```text
>>>>> "Christian" == Christian Glindkamp [ref] writes:

Hi,

 >> So it doesn't really support RGB555 mode. The controller reads up to
 >> 32bit of framebuffer data and outputs 24bit on the LCD pins. You CAN
 >> wire up a RGB555 panel by just skipping the LSB green of a RGB565
 >> wiring, but that is independent of the framebufffer format.

 Christian> But the AT91SAM9261/AT91SAM9263 do not have a native RGB565
 Christian> format if it is configured for 16bit (so it does not read
 Christian> 32bit and output 24bit but just 16bit) but uses BGR555 with
 Christian> an additional intensity bit in the MSB like the palette
 Christian> where you also kept the BGR555 format. How can you get
 Christian> correct colors on these processors if this code above is
 Christian> removed?

I now had a look at the 9261/9263 datasheets, and don't find any
explicit mention of the bit layout of the 16bit/24bit modes. Just to be
completely sure:

- 16bit mode is IBGR-1555 (independently of little/big/wince mode?)
- 24bit is BGR-888 (packed) or XBGR-8888 (unpacked)

Right?

-- 
Bye, Peter Korsgaard
```