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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