Hi Stefan, On Mi, 2019-08-14 at 13:03 +0200, Stefan Agner wrote:
On 2019-08-14 12:48, Robert Chiras wrote:
Add new optional property 'max-res', to limit the maximum supported resolution by the MXSFB_DRM driver.
I would also mention the reason why we need this.
I guess this needs a vendor prefix as well (fsl,max-res). I also would like to have the ack of the device tree folks here.
Rob Herring also aked be about this, and I'll copy here the reply, with explanations:
Indeed, this limitation is actually due to bandwidth limitation, but the problem is that this limitation comes on i.MX8M (known as mScale 850D), where the memory bandwidth cannot support: GPU/VPU workload in the same time with both DCSS driving 4k@60 and eLCDIF driving 1080p@60. Since eLCDIF is a secondary display we though to add the posibility to limit it's bandwidth by limiting the resolution. If you say that more details are needed, I can add them in the description.
-- Stefan
Signed-off-by: Robert Chiras robert.chiras@nxp.com
Documentation/devicetree/bindings/display/mxsfb.txt | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/Documentation/devicetree/bindings/display/mxsfb.txt b/Documentation/devicetree/bindings/display/mxsfb.txt index 472e1ea..55e22ed 100644 --- a/Documentation/devicetree/bindings/display/mxsfb.txt +++ b/Documentation/devicetree/bindings/display/mxsfb.txt @@ -17,6 +17,12 @@ Required properties: Required sub-nodes: - port: The connection to an encoder chip.
+Optional properties: +- max-res: an array with a maximum of two integers, representing the + maximum supported resolution, in the form of + <maxX>, <maxY>; if one of the item is <0>, the default + driver-defined maximum resolution for that axis is used
Example:
lcdif1: display-controller@2220000 {
Thanks, Robert