On Tue, Jul 14, 2020 at 3:18 PM Florian Fainelli [off-list ref] wrote:

On 7/14/2020 2:07 PM, Rob Herring wrote:

quoted

On Tue, Jul 14, 2020 at 01:59:21PM +0200, Nicolas Saenz Julienne wrote:

quoted

On Mon, 2020-07-13 at 12:23 -0600, Rob Herring wrote:

quoted

On Fri, Jun 12, 2020 at 07:13:25PM +0200, Nicolas Saenz Julienne wrote:

quoted

The firmware running on the RPi VideoCore can be used to reset and
initialize HW controlled by the firmware.

Signed-off-by: Nicolas Saenz Julienne <redacted>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

---
Changes since v2:
 - Add include file for reset IDs

Changes since v1:
 - Correct cells binding as per Florian's comment
 - Change compatible string to be more generic

 .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 21 +++++++++++++++++++
 .../reset/raspberrypi,firmware-reset.h        | 13 ++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 include/dt-bindings/reset/raspberrypi,firmware-reset.h

diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-

firmware.yaml
b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-
firmware.yaml
index b48ed875eb8e..23a885af3a28 100644

--- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-

firmware.yaml

+++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-

firmware.yaml

@@ -39,6 +39,22 @@ properties:
       - compatible
       - "#clock-cells"

+  reset:

I'm not really thrilled how this is evolving with a node per provider.
There's no reason you can't just add #clock-cells and #reset-cells to
the parent firmware node.

What are the downsides? The way I see it there is not much difference. And this
way of handling things is feels more intuitive and flexible (overlays can
control what to enable easily, we can take advantage of the platform device
core).

What the OS wants can evolve, so designing around the current needs of
the OS is not how bindings should be done.

Using overlays to add clocks or resets wouldn't really work given they
are spread out over the tree. And with clocks in particular, you'd have
to replace dummy fixed clocks with actual firmware clocks. Sounds
fragile and messy...

quoted

quoted

I probably should have complained with the clocks node, but that's only
pending for 5.9.

Note that there are more users for this pattern: "raspberrypi,firmware-ts" and
"raspberrypi,firmware-gpio". Actually you were the one to originally propose
this it[1]. :P

Sigh, this is why I dislike incomplete examples...

Based on that,

Acked-by: Rob Herring <robh@kernel.org>

And please get gpio and ts converted to schema and referenced here
before the next time I look at this.

quoted

There already is a fair amount of churn in these drivers because of all the DT
changes we did in the past, and if we need to change how we integrate these
again, I'd really like it to be for good.

quoted

The bigger issue is this stuff is just trickling in one bit at a time
which gives no context for review. What's next? Is it really a mystery
as to what functions the firmware provides?

We have no control over it, RPi engineers integrate new designs and new
firmware interfaces show up. This is a good example of it.

I proposed them to use SCMI as it covers most of what they are already
providing here. But no luck so far.

Once we get tired of supporting all the different firmware interfaces
and the mess they become, we'll just have to start refusing custom ones.
Worked for PSCI.

In this particular case, the Raspberry Pi Foundation VPU firmware should
just implement SCMI and that would avoid having to write new client
drivers for Linux, it is not clear to me why this has not been done yet.

Writing drivers is fun?

Perhaps we should start refusing new firmware interfaces now.

Rob