[RFC PATCH 00/10] Support simple-framebuffer on imx8m

[RFC PATCH 00/10] Support simple-framebuffer on imx8m

[Dario Binacchi]

This series is the Linux counterpart of what was sent to U-Boot [1]
for the support of the simple-framebuffer for the BSH SMM S2Pro board.

The need to avoid re-initializing the hardware (power domains,
controllers, bridges, display panels) that has already been initialized
and kept powered on by the bootloader has required updating more than
one YAML file, with the addition of boolean properties to inform the
driver that the corresponding hardware has been initialized and left
on by the bootloader. All these properties are added on the fly by the
bootloader to the various relevant nodes.

Support for the simple framebuffer for the dts of imx8mn-bsh-smm-s2/pro
board has been sent with a separate patch from this series [2].

[1] https://lore.kernel.org/all/20240913095622.72377-18-dario.binacchi@amarulasolutions.com/T/
[2] https://lore.kernel.org/imx/20241024102800.3481574-1-dario.binacchi@amarulasolutions.com/T/


Dario Binacchi (10):
  dt-bindings: soc: imx-blk-ctrl: add 'fsl,power-domains-boot-on'
    property
  pmdomain: imx8m-blk-ctrl: don't turn on a power domain already on
  dt-bindings: power: gpcv2: add 'fsl,boot-on' property
  pmdomain: imx: gpcv2: don't turn on a power domain already on
  dt-bindings: display: panel: add 'syna,boot-on' property
  drm/panel: synaptics-r63353: don't re-activate the panel if already
    setup
  dt-bindings: bridge: samsung-dsim: add 'samsung,boot-on' property
  drm: bridge: samsung-dsim: don't re-activate the bridge if already
    setup
  dt-bindings: lcdif: add 'fsl,boot-on' property
  drm/mxsfb: stop controller and drain FIFOs if already initialized

 .../display/bridge/samsung,mipi-dsim.yaml     |  5 ++
 .../bindings/display/fsl,lcdif.yaml           |  5 ++
 .../display/panel/synaptics,r63353.yaml       |  5 ++
 .../bindings/power/fsl,imx-gpcv2.yaml         |  6 +++
 .../soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml     |  9 ++++
 drivers/gpu/drm/bridge/samsung-dsim.c         | 13 ++++-
 drivers/gpu/drm/mxsfb/mxsfb_drv.c             |  3 ++
 drivers/gpu/drm/mxsfb/mxsfb_drv.h             |  1 +
 drivers/gpu/drm/mxsfb/mxsfb_kms.c             | 14 ++++-
 .../gpu/drm/panel/panel-synaptics-r63353.c    | 10 +++-
 drivers/pmdomain/imx/gpcv2.c                  | 32 +++++++++++-
 drivers/pmdomain/imx/imx8m-blk-ctrl.c         | 51 ++++++++++++++++++-
 12 files changed, 148 insertions(+), 6 deletions(-)

-- 
2.43.0

[RFC PATCH 01/10] dt-bindings: soc: imx-blk-ctrl: add 'fsl,power-domains-boot-on' property

[Dario Binacchi]

This property lists the state of the power domains, indicating whether
they have been left on or off by the bootloader/firmware.
This information becomes relevant, for example, in the case of supporting
the simple framebuffer.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

 .../bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml       | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml b/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml
index eeec9965b091..00aa0b8d8ea9 100644
--- a/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml
+++ b/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml
@@ -56,6 +56,15 @@ properties:
       - const: csi-aclk
       - const: csi-pclk
 
+  fsl,power-domains-boot-on:
+    description: |
+      Provide the on/off (1/0) status of the power domains. It allows
+      specifying whether one or more power domains have already been
+      initialized and left powered on by the bootloader.
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    minItems: 5
+    maxItems: 5
+
 required:
   - compatible
   - reg
-- 
2.43.0

[RFC PATCH 03/10] dt-bindings: power: gpcv2: add 'fsl,boot-on' property

[Dario Binacchi]

The property states that the power-domain has been initialized and left
on by the bootloader/firmware. This information becomes relevant, for
example, in the case of supporting the simple framebuffer.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

 Documentation/devicetree/bindings/power/fsl,imx-gpcv2.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/power/fsl,imx-gpcv2.yaml b/Documentation/devicetree/bindings/power/fsl,imx-gpcv2.yaml
index dfdb8dfb6b65..718196f516ad 100644
--- a/Documentation/devicetree/bindings/power/fsl,imx-gpcv2.yaml
+++ b/Documentation/devicetree/bindings/power/fsl,imx-gpcv2.yaml
@@ -94,6 +94,12 @@ properties:
             minItems: 1
             maxItems: 4
 
+          fsl,boot-on:
+            description: |
+              The power-domain has been initialized and left on  by the
+              bootloader/firmware.
+            type: boolean
+
         required:
           - '#power-domain-cells'
           - reg
-- 
2.43.0

[RFC PATCH 05/10] dt-bindings: display: panel: add 'syna,boot-on' property

[Dario Binacchi]

The property states that the panel display has been initialized and left
on by the bootloader. This information becomes relevant in the case of
supporting the simple framebuffer.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

 .../devicetree/bindings/display/panel/synaptics,r63353.yaml  | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/panel/synaptics,r63353.yaml b/Documentation/devicetree/bindings/display/panel/synaptics,r63353.yaml
index 2fd6e0ec3682..987fd6f8b866 100644
--- a/Documentation/devicetree/bindings/display/panel/synaptics,r63353.yaml
+++ b/Documentation/devicetree/bindings/display/panel/synaptics,r63353.yaml
@@ -25,6 +25,11 @@ properties:
   avdd-supply: true
   dvdd-supply: true
 
+  syna,boot-on:
+    description: |
+      The display has been initialized and left on by the bootloader/firmware.
+    type: boolean
+
 required:
   - compatible
   - reg
-- 
2.43.0

[RFC PATCH 07/10] dt-bindings: bridge: samsung-dsim: add 'samsung,boot-on' property

[Dario Binacchi]

The property states that the bridge controller has been initialized and
left on by the bootloader. This information becomes relevant in the case
of supporting the simple framebuffer.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

 .../bindings/display/bridge/samsung,mipi-dsim.yaml           | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/bridge/samsung,mipi-dsim.yaml b/Documentation/devicetree/bindings/display/bridge/samsung,mipi-dsim.yaml
index 4ed7a799ba26..34cd93bc41f9 100644
--- a/Documentation/devicetree/bindings/display/bridge/samsung,mipi-dsim.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/samsung,mipi-dsim.yaml
@@ -132,6 +132,11 @@ properties:
             dependencies:
               lane-polarities: [data-lanes]
 
+  samsung,boot-on:
+    description:
+      The bridge has been initialized and left on by the bootloader/firmware.
+    type: boolean
+
 required:
   - clock-names
   - clocks
-- 
2.43.0

[RFC PATCH 09/10] dt-bindings: lcdif: add 'fsl,boot-on' property

[Dario Binacchi]

The property states that the (e)LCDIF display controller has been
initialized and left on by the bootloader. This information becomes
relevant in the case of supporting the simple framebuffer.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

 Documentation/devicetree/bindings/display/fsl,lcdif.yaml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/fsl,lcdif.yaml b/Documentation/devicetree/bindings/display/fsl,lcdif.yaml
index 8e3a98aeec32..937f108daacb 100644
--- a/Documentation/devicetree/bindings/display/fsl,lcdif.yaml
+++ b/Documentation/devicetree/bindings/display/fsl,lcdif.yaml
@@ -71,6 +71,11 @@ properties:
     $ref: /schemas/graph.yaml#/properties/port
     description: The LCDIF output port
 
+  fsl,boot-on:
+    description: |
+      The controller has been initialized and left on by the bootloader/firmware.
+    type: boolean
+
 required:
   - compatible
   - reg
-- 
2.43.0

Re: [RFC PATCH 00/10] Support simple-framebuffer on imx8m

[Maxime Ripard]

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Hi,

On Mon, Oct 28, 2024 at 11:25:23AM +0100, Dario Binacchi wrote:
> This series is the Linux counterpart of what was sent to U-Boot [1]
> for the support of the simple-framebuffer for the BSH SMM S2Pro board.

I'm confused. simple-framebuffer is a mechanism for which the entire
point is that the kernel doesn't need the driver for.

Why do you need to have patches for bridges and panels for
simple-framebuffer? They won't be used.

> The need to avoid re-initializing the hardware (power domains,
> controllers, bridges, display panels) that has already been initialized
> and kept powered on by the bootloader has required updating more than
> one YAML file, with the addition of boolean properties to inform the
> driver that the corresponding hardware has been initialized and left
> on by the bootloader. All these properties are added on the fly by the
> bootloader to the various relevant nodes.

So it's not about simple-framebuffer at all, but rather that you don't
want to re-initialize the hardware that has already been setup?

If so, this isn't how you should do it, but rather:
https://lore.kernel.org/all/CAKMK7uHtqHy_oz4W7F+hmp9iqp7W5Ra8CxPvJ=9BwmvfU-O0gg@mail.gmail.com/

Maxime

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Re: [RFC PATCH 01/10] dt-bindings: soc: imx-blk-ctrl: add 'fsl,power-domains-boot-on' property

[Rob Herring]

On Mon, Oct 28, 2024 at 11:25:24AM +0100, Dario Binacchi wrote:
> This property lists the state of the power domains, indicating whether
> they have been left on or off by the bootloader/firmware.
> This information becomes relevant, for example, in the case of supporting
> the simple framebuffer.
> 
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> ---
> 
>  .../bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml       | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml b/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml
> index eeec9965b091..00aa0b8d8ea9 100644
> --- a/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml
> +++ b/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml
> @@ -56,6 +56,15 @@ properties:
>        - const: csi-aclk
>        - const: csi-pclk
>  
> +  fsl,power-domains-boot-on:
> +    description: |
> +      Provide the on/off (1/0) status of the power domains. It allows
> +      specifying whether one or more power domains have already been
> +      initialized and left powered on by the bootloader.

Sounds like a common problem *if* we wanted to fix it in DT.

Why can't you just read the h/w registers to see which domains are 
powered on? Perhaps because some are on, but you want to turn them off.

Also, for simple-framebuffer, I think you can list the power-domains to 
keep on.

Rob

Re: [RFC PATCH 01/10] dt-bindings: soc: imx-blk-ctrl: add 'fsl,power-domains-boot-on' property

[Dario Binacchi]

Hello Rob,

On Fri, Nov 1, 2024 at 6:39 PM Rob Herring <robh@kernel.org> wrote:
>
> On Mon, Oct 28, 2024 at 11:25:24AM +0100, Dario Binacchi wrote:
> > This property lists the state of the power domains, indicating whether
> > they have been left on or off by the bootloader/firmware.
> > This information becomes relevant, for example, in the case of supporting
> > the simple framebuffer.
> >
> > Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> > ---
> >
> >  .../bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml       | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml b/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml
> > index eeec9965b091..00aa0b8d8ea9 100644
> > --- a/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml
> > +++ b/Documentation/devicetree/bindings/soc/imx/fsl,imx8mn-disp-blk-ctrl.yaml
> > @@ -56,6 +56,15 @@ properties:
> >        - const: csi-aclk
> >        - const: csi-pclk
> >
> > +  fsl,power-domains-boot-on:
> > +    description: |
> > +      Provide the on/off (1/0) status of the power domains. It allows
> > +      specifying whether one or more power domains have already been
> > +      initialized and left powered on by the bootloader.
>
> Sounds like a common problem *if* we wanted to fix it in DT.
>
> Why can't you just read the h/w registers to see which domains are
> powered on? Perhaps because some are on, but you want to turn them off.

I checked, but there is no register on this platform that indicates
the on/off status
of the power domain. So, I cannot readout the power domain state.

>
> Also, for simple-framebuffer, I think you can list the power-domains to
> keep on.

I did it; I added the power domains in the simple-framebuffer node, but this
doesn’t prevent the genpd.power_on() callback from being called. And when
this callback is called, the power domain is re-initialized, which does not
maintain the persistence of the image on the display. Adding this DTS property
prevents re-initialization that has already been performed by the bootloader.

Thanks and regards,
Dario

>
> Rob
>
>


-- 

Dario Binacchi

Senior Embedded Linux Developer

dario.binacchi@amarulasolutions.com

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