linux-kernel - Re: [PATCH] drm/msm/a6xx: Add support for an interconnect path

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Date:   Tue, 12 Feb 2019 11:16:24 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Georgi Djakov <georgi.djakov@...aro.org>
Cc:     jcrouse@...eaurora.org, robdclark@...il.com, evgreen@...omium.org,
        freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/msm/a6xx: Add support for an interconnect path

On Tue, Feb 12, 2019 at 11:52:38AM +0200, Georgi Djakov wrote:
> From: Jordan Crouse <jcrouse@...eaurora.org>
> 
> Try to get the interconnect path for the GPU and vote for the maximum
> bandwidth to support all frequencies. This is needed for performance.
> Later we will want to scale the bandwidth based on the frequency to
> also optimize for power but that will require some device tree
> infrastructure that does not yet exist.
> 
> v6: use icc_set_bw() instead of icc_set()
> v5: Remove hardcoded interconnect name and just use the default
> v4: Don't use a port string at all to skip the need for names in the DT
> v3: Use macros and change port string per Georgi Djakov
> 
> Signed-off-by: Jordan Crouse <jcrouse@...eaurora.org>
> Acked-by: Rob Clark <robdclark@...il.com>
> Reviewed-by: Evan Green <evgreen@...omium.org>
> Signed-off-by: Georgi Djakov <georgi.djakov@...aro.org>
> ---
> 
> Hi Greg,
> 
> If not too late, could you please take this patch into char-misc-next.
> It is adding the first consumer of the interconnect API. We are just
> getting the code in place, without making it functional yet, as some
> DT bits are still needed to actually enable it. We have Rob's Ack to
> merge this together with the interconnect code. This patch has already
> spent some time in linux-next without any issues.

I have a question about the interconnect code.  Last week I saw a
presentation about the resctrl/RDT code from ARM that is coming (MPAM),
and it really looks like the same functionality as this interconnect
code.  In fact, this code looks like the existing resctrl stuff, right?

So why shouldn't we just drop the interconnect code and use resctrl
instead as it's already merged?

thanks,

greg k-h