Re: LCDC of 7203

[Fabio Giovagnini <fabio.giovagnini@aurion-tech.com>]

There are some low cost LCD having a parallel interface with the synch signals 
and 16 / 18 bit of data.
The sh2a LCDC can manage such LCD panels

Am I right or not?


In data mercoledì 26 maggio 2010 09:34:36, Magnus Damm ha scritto:
: > On Wed, May 26, 2010 at 3:14 AM, Paul Mundt <lethal@linux-sh.org> wrote:
> > On Wed, May 26, 2010 at 02:20:05AM -0400, Magnus Damm wrote:
> >> On Mon, May 24, 2010 at 1:12 PM, Fabio Giovagnini
> >>
> >> <fabio.giovagnini@aurion-tech.com> wrote:
> >> > Hi all,
> >> > I have a little problem with LCDC of sh2a 7203.
> >> > I seem not to see the driver into the last kernel.
> >> > Where could I find a good reference?
> >>
> >> I don't think there is any upstream 7203 LCDC driver. It's a shame, I
> >> really wish people would submit their code upstream.
> >
> > I don't remember the details specifically, I thought the issue was panel
> > control via MSIOF and so on, which isn't too different from G3EVM?
> 
> Some LCD panels come with a dedicated control channel over SPI/I2C,
> and some have their control channel muxed with pixel data like SYS or
> MIPI.
> 
> I think rsk7203 dealt with the LCD panel setup over SPI, and most
> likely that SPI channel was hooked up to an SIOF or SIO. The MSIOF
> only exists on newer SH-Mobiles, so we would need a new SPI driver for
> SIOF or whatever is there to begin with. Perhaps the easiest is just
> to use an GPIO bitbang driver, but that requires pinmux support which
> probably is in place on some sh2a processor at least.
> 
> > The existing "drivers" are much like the early G3EVM LCD support, so
> > while references are readily available, there's little that is directly
> > usable without some serious work on the infrastructure side. Perhaps we
> > can reuse parts of the SH-Mobile LCD support?
> >
> >From my POV, the biggest showstopper is that the SPI code is lacking
> 
> support for using the bus without the driver model. I2C allows this,
> good or bad. It's sort of a hack, but there is nothing better
> available either. With I2C we can have some board specific support
> code for the LCD panel like the hack on Migo-R. This is not possible
> with SPI AFAIK.
> 
> Perhaps the proper way is to add the LCD panel to the driver model and
> then write a normal SPI driver for the LCD, but that brings up init
> order issues.
> 
> The G3EVM code is setting up the LCD panel using the MSIOF in SPI
> mode. The original code just accessed the MSIOF directly, but we
> should be able to use the SPI driver instead. The MSIOF hardware block
> on SH-Mobile ARM is unfortunately not working well with the MSIOF
> driver, so it's a bit of a mess. SPI bitbang could be useful in this
> case too though if the SPI-without-driver-model could be sorted out.
> 
> I think the MIPI work by Guennadi is one step in the right direction.
> 
> / magnus
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-- 
Fabio Giovagnini

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