Re: [PATCH RESEND 1/3] dt-bindings: add bindings documentation for PDC driver.

On Tue, Jun 14, 2016 at 10:42 AM, Sudeep Holla [off-list ref] wrote:

On 14/06/16 15:02, Rob Rice wrote:

quoted

From: Rob Rice <redacted>

Add the device tree binding documentation for the PDC hardware
in Broadcom iProc SoCs.

Signed-off-by: Rob Rice <redacted>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Ray Jui <redacted>
Reviewed-by: Anup Patel <redacted>
Reviewed-by: Scott Branden <scott.branden@broadcom.com>
---
  .../bindings/mailbox/brcm,iproc-pdc-mbox.txt       | 23
++++++++++++++++++++++
  1 file changed, 23 insertions(+)
  create mode 100644
Documentation/devicetree/bindings/mailbox/brcm,iproc-pdc-mbox.txt

diff --git
a/Documentation/devicetree/bindings/mailbox/brcm,iproc-pdc-mbox.txt
b/Documentation/devicetree/bindings/mailbox/brcm,iproc-pdc-mbox.txt
new file mode 100644
index 0000000..411ccf4

--- /dev/null
+++ b/Documentation/devicetree/bindings/mailbox/brcm,iproc-pdc-mbox.txt

@@ -0,0 +1,23 @@
+The PDC driver manages data transfer to and from various offload engines
+on some Broadcom SoCs. An SoC may have multiple PDC hardware blocks.

There is
+one device tree entry per block.
+
+Required properties:
+- compatible : Should be "brcm,iproc-pdc-mbox".
+- reg: Should contain PDC registers location and length.
+- interrupts: Should contain the IRQ line for the PDC.
+- #mbox-cells: 1
+- brcm,rx-status-len: Length of metadata preceding received frames, in
bytes.
+

Ideally the metadata is more associated with the software protocol built
on top of the mailbox controller.

Is this metadata added by the hardware ?

Otherwise it's better to make it part of the protocol rather than the
associating with the controller.

Yes, in fact this metadata is added by the PDC hardware itself. So it seems
correct for the DT property to be on the controller. (There can be other
metadata associated with the specific protocol (e.g., crypto engine), but
that is accounted for elsewhere.)

+Optional properties:

quoted

+- brcm,use-bcm-hdr:  present if a BCM header precedes each frame.
+

Same here.

Same answer.

--
Regards,
Sudeep