[PATCH v2 1/4] drm: arm: Add DT bindings documentation for HDLCD driver.
Liviu.Dudau at arm.com
Fri Nov 13 02:11:56 PST 2015
On Thu, Nov 12, 2015 at 09:30:31PM -0600, Rob Herring wrote:
> On Thu, Nov 12, 2015 at 4:42 AM, Liviu Dudau <Liviu.Dudau at arm.com> wrote:
> > On Wed, Nov 11, 2015 at 12:48:50PM -0600, Rob Herring wrote:
> >> On Wed, Nov 11, 2015 at 04:06:47PM +0000, Liviu Dudau wrote:
> >> > Cc: Rob Herring <robh+dt at kernel.org>
> >> > Cc: Pawel Moll <pawel.moll at arm.com>
> >> > Cc: Mark Rutland <mark.rutland at arm.com>
> >> > Cc: Ian Campbell <ijc+devicetree at hellion.org.uk>
> >> > Cc: Kumar Gala <galak at codeaurora.org>
> >> >
> >> > Signed-off-by: Liviu Dudau <Liviu.Dudau at arm.com>
> >> Looks pretty good, but a few comments.
> >> > ---
> >> > .../devicetree/bindings/drm/arm/arm,hdlcd.txt | 74 ++++++++++++++++++++++
> >> > 1 file changed, 74 insertions(+)
> >> > create mode 100644 Documentation/devicetree/bindings/drm/arm/arm,hdlcd.txt
> >> >
> >> > diff --git a/Documentation/devicetree/bindings/drm/arm/arm,hdlcd.txt b/Documentation/devicetree/bindings/drm/arm/arm,hdlcd.txt
> >> > new file mode 100644
> >> > index 0000000..b57f1b9
> >> > --- /dev/null
> >> > +++ b/Documentation/devicetree/bindings/drm/arm/arm,hdlcd.txt
> >> > @@ -0,0 +1,74 @@
> >> > +ARM HDLCD
> >> > +
> >> > +This is a display controller found on several development platforms produced
> >> > +by ARM Ltd and in more modern of its' Fast Models. The HDLCD is an RGB
> >> > +streamer that reads the data from a framebuffer and sends it to a single
> >> > +digital encoder (DVI or HDMI).
> >> > +
> >> > +Required properties:
> >> > + - compatible: "arm,hdlcd"
> >> Kind of generic. Something more specific please.
> > "There can be only one!" (hdlcd) :) This is going to be a "one version only" HW part.
> > ARM has now switched to a new display hardware that has more features and a new name,
> > and work on mainlining support for that will start once I get the HDLCD driver accepted.
> So there is never going to be a single difference across platforms.
Correct, there is only one implementation available. AFAIK there are no plans to make changes to it.
> Variations in max clock for different FPGAs?
The clock is external to the part and there is a check in the driver if we can set the frequency
to match the requested dotclock by the video_mode. It does not affect the hardware or how it presents
itself to the driver.
> >> > + - reg: Physical base address and length of the controller's registers.
> >> > + If a second pair of address and length values is present this specifies
> >> > + the presence of a DMA coherent memory area that the HDLCD can use as
> >> > + framebuffer instead of normal CMA memory.
> >> This is on-chip RAM or nornal system RAM? We already have bindings for
> >> both.
> > Juno has a set of TLX (ThinLinks) connectors on the board where an FPGA can be attached. On r1
> > the code running on FPGA can even participate as an AXI master with full coherency. The FPGA
> > has local memory that we want to share with the HDLCD to be used as a framebuffer.
> So describe the memory region and then use a memory-region phandle to
> the memory here.
OK, I will.
> >> > + - interrupts: One interrupt used by the display controller to notify the
> >> > + interrupt controller when any of the interrupt sources programmed in
> >> > + the interrupt mask register have activated.
> >> > + - clocks: A list of phandle + clock-specifier pairs, one for each
> >> > + entry in 'clock-names'.
> >> > + - clock-names: A list of clock names. For HDLD it should contain:
> typo: HDLD
oops, thanks, will fix.
> >> > + - "pxlclk" for the clock feeding the output PLL of the controller.
> >> > + - port: The HDLCD connection to an encoder chip. The connection is modelled
Thanks for reviewing it,
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
More information about the linux-arm-kernel