From: Maxime Ripard <mripard@kernel.org>
To: Stephen Boyd <swboyd@chromium.org>
Cc: Georgi Djakov <georgi.djakov@linaro.org>,
linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org,
Rob Herring <robh+dt@kernel.org>,
devicetree@vger.kernel.org,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Evan Green <evgreen@chromium.org>,
David Dai <daidavid1@codeaurora.org>
Subject: Re: [RFC PATCH] interconnect: Replace of_icc_get() with icc_get() and reduce DT binding
Date: Wed, 25 Sep 2019 11:15:22 +0200 [thread overview]
Message-ID: <20190925091522.jf5q2jdo6njfkxto@gilmour> (raw)
In-Reply-To: <20190925054133.206992-1-swboyd@chromium.org>
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Hi Stephen,
On Tue, Sep 24, 2019 at 10:41:33PM -0700, Stephen Boyd wrote:
> The DT binding could also be simplified somewhat. Currently a path needs
> to be specified in DT for each and every use case that is possible for a
> device to want. Typically the path is to memory, which looks to be
> reserved for in the binding with the "dma-mem" named path, but sometimes
> the path is from a device to the CPU or more generically from a device
> to another device which could be a CPU, cache, DMA master, or another
> device if some sort of DMA to DMA scenario is happening. Let's remove
> the pair part of the binding so that we just list out a device's
> possible endpoints on the bus or busses that it's connected to.
>
> If the kernel wants to figure out what the path is to memory or the CPU
> or a cache or something else it should be able to do that by finding the
> node for the "destination" endpoint, extracting that node's
> "interconnects" property, and deriving the path in software. For
> example, we shouldn't need to write out each use case path by path in DT
> for each endpoint node that wants to set a bandwidth to memory. We
> should just be able to indicate what endpoint(s) a device sits on based
> on the interconnect provider in the system and then walk the various
> interconnects to find the path from that source endpoint to the
> destination endpoint.
The dma-mem name is used by the OF core to adjust the mapping of the
devices as well. So, any solution needs to be generic (or provide a
generic helper).
Maxime
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prev parent reply other threads:[~2019-09-25 9:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 5:41 [RFC PATCH] interconnect: Replace of_icc_get() with icc_get() and reduce DT binding Stephen Boyd
2019-09-25 5:59 ` Bjorn Andersson
2019-09-25 13:28 ` Stephen Boyd
2019-09-27 17:16 ` David Dai
2019-10-04 18:14 ` Stephen Boyd
2019-10-09 0:11 ` Saravana Kannan
2019-10-16 20:23 ` Stephen Boyd
2019-09-25 9:15 ` Maxime Ripard [this message]
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