Messages in this thread | | | Subject | Re: Allocation of frame buffer at a specific memory range or address | From | Vineet Gupta <> | Date | Sat, 16 Apr 2016 11:37:20 +0530 |
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On Friday 15 April 2016 09:18 PM, Alexey Brodkin wrote:
> And now the question is how to force DRM subsystem or just that driver > to use whatever predefined (say via device tree) location in memory > for data buffer allocation.
It seems this is pretty easy to do with DT reserved-memory binding.
You need to partition memory into @memory and @reserved-memory. Later can be subdivided into more granular regions and your driver can refer to one of the regions.
Something like below (untested)
+ memory { + device_type = "memory"; + reg = <0x0 0x80000000 0x0 0xA0000000>; + #address-cells = <2>; + #size-cells = <2>; + }; + + reserved-memory { + #address-cells = <2>; + #size-cells = <2>; + ranges; + /* This memory bypasses IOC port */ + fb_reserved@A0000000 { + reg = <0x0 0xA0000000 0x0 0xAF000000>; + #address-cells = <2>; + #size-cells = <2>; + /* no-map; */ + }; + }; + + + fb0: video@12300000 { + memory-region = <&fb_reserved>; + /* ... */ + };
This might also need a DT helper in ARC mm init code.
+ early_init_fdt_scan_reserved_mem();
HTH, -Vineet
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