From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vineet Gupta Subject: Re: Allocation of frame buffer at a specific memory range or address Date: Sat, 16 Apr 2016 11:37:20 +0530 Message-ID: <5711D698.4030606@synopsys.com> References: <1460735338.3248.21.camel@synopsys.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1460735338.3248.21.camel-HKixBCOQz3hWk0Htik3J/w@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alexey Brodkin , "dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org" Cc: "daniel-/w4YWyX8dFk@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-snps-arc-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "airlied-cv59FeDIM0c@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Rob Herring List-Id: devicetree@vger.kernel.org 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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html