On 26.09.2017 08:11, Stephen Warren wrote: > On 09/25/2017 05:45 PM, Dmitry Osipenko wrote: >> On 26.09.2017 02:01, Stephen Warren wrote: >>> On 09/25/2017 04:15 PM, Dmitry Osipenko wrote: >>>> Video decoder, found on NVIDIA Tegra20 SoC, supports a standard set of >>>> video formats like H.264 / MPEG-4 / WMV / VC1. Currently driver supports >>>> decoding of CAVLC H.264 only. >>> >>> Note: I don't know anything much about video decoding on Tegra (just NV desktop >>> GPUs, and that was a while ago), but I had a couple small comments on the DT >>> binding: >>> >>>> diff --git >>>> a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-vde.txt >>>> b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-vde.txt >>> >>>> +NVIDIA Tegra Video Decoder Engine >>>> + >>>> +Required properties: >>>> +- compatible : "nvidia,tegra20-vde" >>>> +- reg : Must contain 2 register ranges: registers and IRAM area. >>>> +- reg-names : Must include the following entries: >>>> + - regs >>>> + - iram >>> >>> I think the IRAM region needs more explanation: What is the region used for and >>> by what? Can it be moved, and if so does the move need to be co-ordinated with >>> any other piece of SW? >> >> IRAM region is used by Video Decoder HW for internal use and some of decoding >> parameters are supplied via IRAM, like frames order list. AFAIK IRAM addresses >> are hardwired in HW and aren't movable, it is not 100% but I'm pretty sure. >> Should it be explained in the binding? > > I think this should be briefly mentioned, yes. Otherwise at least people > who don't know the VDE HW well (like me) will wonder why on earth VDE > interacts with IRAM at all. I would have assumed all parameters were > supplied via registers or via descriptors in DRAM. > > Thanks. > I also forgot to mention that VDE scrubs that IRAM region on HW reset. So yeah, it's definitely a part of HW definition. I'll add a brief explanation to the binding. -- Dmitry _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
