linux-media.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Maxime Ripard <maxime@cerno.tech>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Stefan Wahren <stefan.wahren@i2se.com>,
	Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>,
	dave.stevenson@raspberrypi.com, devicetree@vger.kernel.org,
	kernel-list@raspberrypi.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
	linux-rpi-kernel@lists.infradead.org, lukasz@jany.st,
	mchehab@kernel.org, naush@raspberrypi.com, robh@kernel.org,
	tomi.valkeinen@ideasonboard.com,
	bcm-kernel-feedback-list@broadcom.com,
	Florian Fainelli <f.fainelli@gmail.com>
Subject: Re: [PATCH v5 03/11] dt-bindings: media: Add bindings for bcm2835-unicam
Date: Mon, 21 Feb 2022 11:03:09 +0100	[thread overview]
Message-ID: <20220221100309.ytcy6bxijwztyhsd@houat> (raw)
In-Reply-To: <YhM6474MwSh6bjUe@pendragon.ideasonboard.com>

[-- Attachment #1: Type: text/plain, Size: 5258 bytes --]

On Mon, Feb 21, 2022 at 09:10:27AM +0200, Laurent Pinchart wrote:
> Hi Stefan,
> 
> On Mon, Feb 14, 2022 at 12:32:59PM +0100, Stefan Wahren wrote:
> > Am 14.02.22 um 10:54 schrieb Laurent Pinchart:
> > > On Mon, Feb 14, 2022 at 10:39:54AM +0100, Maxime Ripard wrote:
> > >> On Sun, Feb 13, 2022 at 04:48:45PM +0100, Stefan Wahren wrote:
> > >>> as someone with a little more insight to the clocks, i like to know your
> > >>> opinion about the bcm2835-unicam binding.
> > >>>
> > >>> Am 08.02.22 um 16:50 schrieb Jean-Michel Hautbois:
> > >>>> Introduce the dt-bindings documentation for bcm2835 CCP2/CSI2 Unicam
> > >>>> camera interface.
> > >>>>
> > >>>> Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
> > >>>> Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> > >>>> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
> > >>>> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > >>>>
> > >>>> ---
> > >>>> v4:
> > >>>> - make MAINTAINERS its own patch
> > >>>> - describe the reg and clocks correctly
> > >>>> - use a vendor entry for the number of data lanes
> > >>>> ---
> > >>>>  .../bindings/media/brcm,bcm2835-unicam.yaml   | 117 ++++++++++++++++++
> > >>>>  1 file changed, 117 insertions(+)
> > >>>>  create mode 100644 Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml
> > >>>>
> > >>>> diff --git a/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml b/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml
> > >>>> new file mode 100644
> > >>>> index 000000000000..1938ace23b3d
> > >>>> --- /dev/null
> > >>>> +++ b/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml
> > >>>> @@ -0,0 +1,117 @@
> > >>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > >>>> +%YAML 1.2
> > >>>> +---
> > >>>> +$id: http://devicetree.org/schemas/media/brcm,bcm2835-unicam.yaml#
> > >>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > >>>> +
> > >>>> +title: Broadcom BCM283x Camera Interface (Unicam)
> > >>>> +
> > >>>> +maintainers:
> > >>>> +  - Raspberry Pi Kernel Maintenance <kernel-list@raspberrypi.com>
> > >>>> +
> > >>>> +description: |-
> > >>>> +  The Unicam block on BCM283x SoCs is the receiver for either
> > >>>> +  CSI-2 or CCP2 data from image sensors or similar devices.
> > >>>> +
> > >>>> +  The main platform using this SoC is the Raspberry Pi family of boards.  On
> > >>>> +  the Pi the VideoCore firmware can also control this hardware block, and
> > >>>> +  driving it from two different processors will cause issues.  To avoid this,
> > >>>> +  the firmware checks the device tree configuration during boot. If it finds
> > >>>> +  device tree nodes whose name starts with 'csi' then it will stop the firmware
> > >>>> +  accessing the block, and it can then safely be used via the device tree
> > >>>> +  binding.
> > >>>> +
> > >>>> +properties:
> > >>>> +  compatible:
> > >>>> +    const: brcm,bcm2835-unicam
> > >>>> +
> > >>>> +  reg:
> > >>>> +    items:
> > >>>> +      - description: Unicam block.
> > >>>> +      - description: Clock Manager Image (CMI) block.
> > >>>> +
> > >>>> +  reg-names:
> > >>>> +    items:
> > >>>> +      - const: unicam
> > >>>> +      - const: cmi
> > >>>> +
> > >>>> +  interrupts:
> > >>>> +    maxItems: 1
> > >>>> +
> > >>>> +  clocks:
> > >>>> +    items:
> > >>>> +      - description: Clock to drive the LP state machine of Unicam.
> > >>>> +      - description: Clock for the VPU (core clock).
> > >>>> +
> > >>>> +  clock-names:
> > >>>> +    items:
> > >>>> +      - const: lp
> > >>>> +      - const: vpu
> > >>>> +
> > >>>
> > >>> according to this patch [1], the unicam driver only needs the VPU clock
> > >>> reference just to enforce a minimum of 250 MHz. The firmware clock
> > >>> binding and its driver is specific to the bcm2711, but the Unicam IP
> > >>> exists since bcm2835.
> > >>>
> > >>> So do you think the clock part is correct or should be the VPU clock
> > >>> optional?
> > >>
> > >> I think we should keep it mandatory. Indeed, that clock is shared with
> > >> the HVS that will change its rate on a regular basis, so even just
> > >> enforcing that 250MHz while it's on without a clock handle will be
> > >> fairly hard.
> > >>
> > >> Also, those are the constraints we have now, but having the clock handle
> > >> all the time will allow us to add any constraint we might need in the
> > >> future.
> > >>
> > >> And BCM2711 or not, the clock has probably always been there.
> > >
> > > Furthermore, regardless of what the driver needs, Unicam operates with
> > > the VPU clock, so I think it makes sense to reference it in the device
> > > tree.
> > 
> > okay, as a result we need a DTS patch for bcm2835-rpi.dtsi to enable the
> > firmware clocks and its driver in this series.
> 
> Can't we do that on top, enabling Unicam support for bcm2711 only first
> ? I have no idea how to deal with firmware clocks on bcm2825, and I'm
> not sure Jean-Michel even has a hardware platform to test it.

The RPi kernel uses the firmware clocks driver for all the platforms, so
it shouldn't be too bad.

Maxime

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

  reply	other threads:[~2022-02-21 10:42 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-08 15:50 [PATCH v5 00/11] Add support for BCM2835 camera interface (unicam) Jean-Michel Hautbois
2022-02-08 15:50 ` [PATCH v5 01/11] media: v4l: Add V4L2-PIX-FMT-Y12P format Jean-Michel Hautbois
2022-02-08 15:50 ` [PATCH v5 02/11] media: v4l: Add V4L2-PIX-FMT-Y14P format Jean-Michel Hautbois
2022-02-08 15:50 ` [PATCH v5 03/11] dt-bindings: media: Add bindings for bcm2835-unicam Jean-Michel Hautbois
2022-02-09 18:56   ` Rob Herring
2022-02-13 15:48   ` Stefan Wahren
2022-02-14  9:39     ` Maxime Ripard
2022-02-14  9:54       ` Laurent Pinchart
2022-02-14 11:32         ` Stefan Wahren
2022-02-21  7:10           ` Laurent Pinchart
2022-02-21 10:03             ` Maxime Ripard [this message]
2022-02-21 12:45             ` Stefan Wahren
2022-02-21 12:52               ` Laurent Pinchart
2022-02-25  8:19   ` Sakari Ailus
2022-02-08 15:50 ` [PATCH v5 04/11] media: bcm2835-unicam: Add support for CCP2/CSI2 camera interface Jean-Michel Hautbois
2022-02-08 21:00   ` Stefan Wahren
2022-02-13 12:52     ` Laurent Pinchart
2022-02-13 11:17   ` Stefan Wahren
2022-02-13 12:49     ` Laurent Pinchart
2022-02-20 10:01   ` Stefan Wahren
2022-02-20 10:08     ` Laurent Pinchart
2022-02-21  9:55   ` Laurent Pinchart
2022-02-25  9:29   ` Sakari Ailus
2023-07-02 15:23     ` Laurent Pinchart
2023-07-02 18:18       ` Sakari Ailus
2023-07-02 21:45         ` Laurent Pinchart
2023-07-02 21:47           ` Laurent Pinchart
2023-07-02 21:56             ` Sakari Ailus
2023-07-02 22:01               ` Laurent Pinchart
2023-07-02 22:20                 ` Sakari Ailus
2023-07-02 22:28                   ` Laurent Pinchart
2023-07-02 22:33                     ` Sakari Ailus
2023-07-02 21:53           ` Sakari Ailus
2023-07-02 21:58             ` Laurent Pinchart
2022-02-08 15:50 ` [PATCH v5 05/11] media: MAINTAINERS: add bcm2835 unicam driver Jean-Michel Hautbois
2022-02-08 15:58   ` Laurent Pinchart
2022-02-08 15:50 ` [PATCH v5 06/11] ARM: dts: bcm2711: Add unicam CSI nodes Jean-Michel Hautbois
2022-02-13 10:35   ` Stefan Wahren
2022-02-13 13:51     ` Stefan Wahren
2022-02-08 15:50 ` [PATCH v5 07/11] media: imx219: Rename mbus codes array Jean-Michel Hautbois
2022-02-08 15:50 ` [PATCH v5 08/11] media: imx219: Switch from open to init_cfg Jean-Michel Hautbois
2022-02-08 16:02   ` Laurent Pinchart
2022-02-08 16:05     ` Laurent Pinchart
2022-02-08 15:50 ` [PATCH v5 09/11] media: imx219: Introduce the set_routing operation Jean-Michel Hautbois
2022-02-21  7:17   ` Laurent Pinchart
2022-02-08 15:50 ` [PATCH v5 10/11] media: imx219: use a local v4l2_subdev to simplify reading Jean-Michel Hautbois
2022-02-08 15:50 ` [PATCH v5 11/11] media: imx219: Add support for the V4L2 subdev active state Jean-Michel Hautbois
2022-02-21  7:25   ` Laurent Pinchart
2022-02-16 20:57 ` [PATCH v5 00/11] Add support for BCM2835 camera interface (unicam) Stefan Wahren
2022-02-20 14:30   ` Jean-Michel Hautbois
2022-02-26 17:18     ` Stefan Wahren

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220221100309.ytcy6bxijwztyhsd@houat \
    --to=maxime@cerno.tech \
    --cc=bcm-kernel-feedback-list@broadcom.com \
    --cc=dave.stevenson@raspberrypi.com \
    --cc=devicetree@vger.kernel.org \
    --cc=f.fainelli@gmail.com \
    --cc=jeanmichel.hautbois@ideasonboard.com \
    --cc=kernel-list@raspberrypi.com \
    --cc=laurent.pinchart@ideasonboard.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=linux-rpi-kernel@lists.infradead.org \
    --cc=lukasz@jany.st \
    --cc=mchehab@kernel.org \
    --cc=naush@raspberrypi.com \
    --cc=robh@kernel.org \
    --cc=stefan.wahren@i2se.com \
    --cc=tomi.valkeinen@ideasonboard.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).