| Message ID | 20221007124946.406808-2-thierry.reding@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/simpledrm: Support system memory framebuffers | expand |
On Fri, 07 Oct 2022 14:49:40 +0200, Thierry Reding wrote: > From: Thierry Reding <treding@nvidia.com> > > In order to support framebuffers residing in system memory, allow the > memory-region property to override the framebuffer memory specification > in the "reg" property. > > Signed-off-by: Thierry Reding <treding@nvidia.com> > --- > .../devicetree/bindings/display/simple-framebuffer.yaml | 5 +++++ > 1 file changed, 5 insertions(+) > Reviewed-by: Rob Herring <robh@kernel.org>
Hi Am 07.10.22 um 14:49 schrieb Thierry Reding: > From: Thierry Reding <treding@nvidia.com> > > In order to support framebuffers residing in system memory, allow the > memory-region property to override the framebuffer memory specification > in the "reg" property. What happens if both properties are present and they disagree with each other? I understand that the framebuffer is behind 'memory-region', but does 'reg' still contain device memory? Do we need to acquire ownership from within the driver? Best regards Thomas > > Signed-off-by: Thierry Reding <treding@nvidia.com> > --- > .../devicetree/bindings/display/simple-framebuffer.yaml | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/Documentation/devicetree/bindings/display/simple-framebuffer.yaml b/Documentation/devicetree/bindings/display/simple-framebuffer.yaml > index dd64f70b5014..3e9857eb002e 100644 > --- a/Documentation/devicetree/bindings/display/simple-framebuffer.yaml > +++ b/Documentation/devicetree/bindings/display/simple-framebuffer.yaml > @@ -63,6 +63,11 @@ properties: > reg: > description: Location and size of the framebuffer memory > > + memory-region: > + maxItems: 1 > + description: Phandle to a node describing the memory to be used for the > + framebuffer. If present, overrides the "reg" property (if one exists). > + > clocks: > description: List of clocks used by the framebuffer. >
On Mon, Oct 10, 2022 at 11:37:37AM +0200, Thomas Zimmermann wrote: > Hi > > Am 07.10.22 um 14:49 schrieb Thierry Reding: > > From: Thierry Reding <treding@nvidia.com> > > > > In order to support framebuffers residing in system memory, allow the > > memory-region property to override the framebuffer memory specification > > in the "reg" property. > > What happens if both properties are present and they disagree with each > other? > > I understand that the framebuffer is behind 'memory-region', but does 'reg' > still contain device memory? Do we need to acquire ownership from within > the driver? The intention is for both memory-region and reg properties to be mutually exclusive. I can't think of a scenario where you would need or want both. Note also the documentation for the memory-region property: | memory-region: | maxItems: 1 | description: Phandle to a node describing the memory to be used for the | framebuffer. If present, overrides the "reg" property (if one exists). Thierry
diff --git a/Documentation/devicetree/bindings/display/simple-framebuffer.yaml b/Documentation/devicetree/bindings/display/simple-framebuffer.yaml index dd64f70b5014..3e9857eb002e 100644 --- a/Documentation/devicetree/bindings/display/simple-framebuffer.yaml +++ b/Documentation/devicetree/bindings/display/simple-framebuffer.yaml @@ -63,6 +63,11 @@ properties: reg: description: Location and size of the framebuffer memory + memory-region: + maxItems: 1 + description: Phandle to a node describing the memory to be used for the + framebuffer. If present, overrides the "reg" property (if one exists). + clocks: description: List of clocks used by the framebuffer.