From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: Re: [RFC 2/2] dt-bindings: firmware: tegra186-bpmp: Document interconnects property Date: Tue, 28 Jan 2020 22:27:00 +0300 Message-ID: References: <20200114181519.3402385-1-thierry.reding@gmail.com> <20200114181519.3402385-2-thierry.reding@gmail.com> <7aefac6c-092c-b5a6-2fa6-e283d2147fc3@linaro.org> <20200120150605.GA712203@ulmo> <57c37b3c-1473-d444-db59-8c6650241188@gmail.com> <20200121141027.GE899558@ulmo> <83d94918-bc01-131b-924c-9750767d3b29@linaro.org> <20200121155432.GA912205@ulmo> <20200127122115.GA2117209@ulmo> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200127122115.GA2117209@ulmo> Content-Language: en-US Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding , Georgi Djakov Cc: Rob Herring , Jon Hunter , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org 27.01.2020 15:21, Thierry Reding пишет: > On Tue, Jan 21, 2020 at 11:12:11PM +0300, Dmitry Osipenko wrote: >> 21.01.2020 18:54, Thierry Reding пишет: >>> On Tue, Jan 21, 2020 at 05:18:43PM +0200, Georgi Djakov wrote: >>>> On 1/21/20 16:10, Thierry Reding wrote: > [...] >>>>> I'm not sure if that TEGRA_ICC_EMEM makes a lot of sense. It's always >>>>> going to be the same and it's arbitrarily defined, so it's effectively >>>>> useless. But other than that it looks good. >>>> >>>> Well, in most cases the target would be the EMEM, so that's fine. I have seen >>>> that other vendors that may have an additional internal memory, especially >>>> dedicated to some DSPs and in such cases the bandwidth needs are different for >>>> the two paths (to internal memory and DDR). >>> >>> Most chips have a small internal memory that can be used, though it >>> seldomly is. However, in that case I would expect the target to be a >>> completely different device, so it'd look more like this: >>> >>> interconnects = <&mc TEGRA186_MEMORY_CLIENT_BPMPR &iram>, >>> ...; >>> >>> I don't think EMEM has any "downstream" other than external memory. >> >> The node ID should be mandatory in terms of interconnect, even if it's a >> single node. EMC (provider) != EMEM (endpoint). > > I don't understand why. An ID only makes sense if you've got multiple > endpoints. For example, a regulator is a provider with a single endpoint > so we don't specify an ID. Because this is how ICC binding is defined, unless I'm missing something. > By its very definition an ID is used to identify something and we use it > with a phandle to create a unique pair that identifies a resource within > whatever the phandle represents, with the goal to differentiate it from > other resources within the same provider. However, if there's only one > such resource, the ID becomes redundant because the phandle without an > ID is already unique and there's no need to differentiate with an extra > ID. Georgi, do you think it is possible to support what Thierry is asking for?