Re: [PATCH] auxdisplay: hd44780: move cursor home after clear display command

[poeschel]

Am 2023-07-06 21:49, schrieb Hugo Villeneuve:
> On Thu, 6 Jul 2023 21:33:05 +0200
> Miguel Ojeda <miguel.ojeda.sandonis@xxxxxxxxx> wrote:
>
> > On Thu, Jul 6, 2023 at 8:51 PM Hugo Villeneuve <hugo@xxxxxxxxxxx> 
> > wrote:
> > >
> > > The "clear display" 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 clear display
> > > command.
> > >
> > > Extract of CLEAR_DISPLAY 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 clear display command to support
> > > non-standard LCDs.
> > >
> > > Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
> >
> > Thanks! Sounds good to me, as long the extra command does not
> > introduce some issue with the actual HD44780 -- can we double-check
> > the HD44780 still works as expected?
> >
> > Cc'ing Lars and Geert since they may be able to give it a quick test.
>
> Hi Miguel,
> I do not have a standard Hitachi controller to test it on, so lets wait
> for feedback from Lars and Geert or others.

Sorry guys,
I do not have access to the relevant hardware anymore. I am CC'ing 
Christian,
who has the relevant hardware and maybe he can help testing the patch.
Christian is on vacation up until mid august, so we have to wait a bit 
more
for someone able to test this.

BTW: The displays I did the work back then on were for sure not genuine
Hitachi ones either.
I do not see, that the little patch should do any harm.

Regards,
Lars