| Message ID | 1353236200-11435-1-git-send-email-shc_work@mail.ru (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Nov 18, 2012 at 02:56:40PM +0400, Alexander Shiyan wrote: > arm-charlcd driver can be used on any ARM machine, so dependency of > PLAT_VERSATILE is removed. This needs a better explanation. We know that it's used on ARMs reference boards. Which other platforms will be making use of this driver? Do these other boards implement the same interface, including the presence of the interrupt? I'd need to re-read the specs, but I think that the interface this driver uses is provided by ARMs FPGA rather than the LCD module itself, and re-use of this driver would need that IP to be implemented elsewhere.
> > arm-charlcd driver can be used on any ARM machine, so dependency of > > PLAT_VERSATILE is removed. > > This needs a better explanation. We know that it's used on ARMs > reference boards. Which other platforms will be making use of this > driver? Do these other boards implement the same interface, including > the presence of the interrupt? LCD controller do not have interrupt output. In driver interrupt is optional and used for delay operations, since controller is too slow. Probably, as you say, it used by additional onboard FPGA for a delay read/write operations on fast CPU bus and/or generate clock. All other controller signals are normal CPU-bus signals. > I'd need to re-read the specs, but I think that the interface this > driver uses is provided by ARMs FPGA rather than the LCD module itself, > and re-use of this driver would need that IP to be implemented elsewhere. Commands in the driver - is a controller commands, so it can be reused by other machines. For example, I want to reuse this driver for clps711x. Detail description of controller present on wiki: http://en.wikipedia.org/wiki/HD44780_Character_LCD ---
> > arm-charlcd driver can be used on any ARM machine, so dependency of > > PLAT_VERSATILE is removed. > > This needs a better explanation. We know that it's used on ARMs > reference boards. Which other platforms will be making use of this > driver? Do these other boards implement the same interface, including > the presence of the interrupt? > > I'd need to re-read the specs, but I think that the interface this > driver uses is provided by ARMs FPGA rather than the LCD module itself, > and re-use of this driver would need that IP to be implemented elsewhere. Additionally: But, you are right. This should be reviewed more accuracy for a support for other machines, so please drop this patch. ---
On Sun, Nov 18, 2012 at 03:49:26PM +0400, Alexander Shiyan wrote: > > > arm-charlcd driver can be used on any ARM machine, so dependency of > > > PLAT_VERSATILE is removed. > > > > This needs a better explanation. We know that it's used on ARMs > > reference boards. Which other platforms will be making use of this > > driver? Do these other boards implement the same interface, including > > the presence of the interrupt? > > > > I'd need to re-read the specs, but I think that the interface this > > driver uses is provided by ARMs FPGA rather than the LCD module itself, > > and re-use of this driver would need that IP to be implemented elsewhere. > Additionally: But, you are right. This should be reviewed more accuracy for a > support for other machines, so please drop this patch. What would be nice to see is a driver library for these LCD modules which can then be hooked into whatever interface a platform presents, and come up with some kind of solution to that where the platform interface can be represented in DT form.
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig index b151b7c..ac67ce5 100644 --- a/drivers/misc/Kconfig +++ b/drivers/misc/Kconfig @@ -434,13 +434,14 @@ config VMWARE_BALLOON config ARM_CHARLCD bool "ARM Ltd. Character LCD Driver" - depends on PLAT_VERSATILE - help - This is a driver for the character LCD found on the ARM Ltd. - Versatile and RealView Platform Baseboards. It doesn't do - very much more than display the text "ARM Linux" on the first - line and the Linux version on the second line, but that's - still useful. + depends on ARM + help + This is a driver for the on-board character LCD found on some + ARM reference boards, for example on Versatile or RealView Platform + Baseboards. This is basically an Hitachi HD44780 LCD. + Driver doesn't do very much more than display the text "ARM Linux" + on the first line and the Linux version on the second line, but + that's still useful. config BMP085 bool
arm-charlcd driver can be used on any ARM machine, so dependency of PLAT_VERSATILE is removed. Signed-off-by: Alexander Shiyan <shc_work@mail.ru> --- drivers/misc/Kconfig | 15 ++++++++------- 1 files changed, 8 insertions(+), 7 deletions(-)