On Tue, Dec 5, 2023 at 4:31 AM Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > 6.1-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx> > > commit 35b464e32c8bccef435e415db955787ead4ab44c upstream. > > The DISPLAY_CLEAR command on the NewHaven NHD-0220DZW-AG5 display > does NOT change the DDRAM address to 00h (home position) like the > standard Hitachi HD44780 controller. As a consequence, the starting > position of the initial string LCD_INIT_TEXT is not guaranteed to be > at 0,0 depending on where the cursor was before the DISPLAY_CLEAR > command. > > Extract of DISPLAY_CLEAR command from datasheets of: > > Hitachi HD44780: > ... It then sets DDRAM address 0 into the address counter... > > NewHaven NHD-0220DZW-AG5 datasheet: > ... This instruction does not change the DDRAM Address > > Move the cursor home after sending DISPLAY_CLEAR command to support > non-standard LCDs. > > Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx> > Reviewed-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> > Tested-by: David Reaver <me@xxxxxxxxxxxxxxx> > Link: https://lore.kernel.org/r/20230722180925.1408885-1-hugo@xxxxxxxxxxx > Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> The commit enables more hardware to work, so it is a "feature" in sense. It does not break the current supported hardware (as far as we know -- David's `Tested-by` was on HD44780), but as usual, there is always a risk with any change. If it is OK to take commits like this into stable or somebody wanted to use that hardware in 6.1, then I assume it is fine, but I wanted to point it out just in case. Thanks! Cheers, Miguel
