Re: [PATCH V3] LCD Display Driver lcddisplay, ks0108, cfag12864b

From: Miguel Ojeda
Date: Wed Sep 13 2006 - 10:25:54 EST


Please reply in the last patch version, subject:

[PATCH 2/2] drivers: LCD Display support.

On 9/13/06, Ben Dooks <ben-linux@xxxxxxxxx> wrote:
I think there would be a case for splitting the lcd
drivers into two layers, one to deal with the hardware
talking to an lcd device (such as an parallel port)
and the second to deal with the command sequences
being sent.


It is divided already in two layers:

ks0108.c -> It is the driver for a LCD controller. It deals with the
hardware (not directly, it uses parport module). It exports the
functions defined for such controller to other modules.

cfag12864b.c -> It is a LCD driver, depends on ks0108. This is the
driver that tells what and how to write.

For instance, we have two boards based on ARM which
use a CPLD to decode CS1 and CS2, etc. This would
mean re-writing your driver (and anyone elses)
depending on what sort of LCD we would like to
connect to these.


I don't think so. The ks0108 controller driver was built to control
the LCD using the parallel port and a specific wiring.

If you want to use your boards, write a driver for them. What is the problem.

(Please tell me if I misunderstood you)

If there was an generic device driver, then you
could export the writing of bytes to user-space
and have them use the hardware to do any protocol
they liked.


A generic driver for what? There are many different ports/wirings,
different LCDs displays, different LCD controllers, different
protocols...

I didn't understand what do you mean.
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