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From:   Florian Fainelli <f.fainelli@gmail.com>
To:     bcm-kernel-feedback-list@broadcom.com,
        Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Eric Anholt <eric@anholt.net>, Stefan Wahren <wahrenst@gmx.net>
Cc:     mbrugger@suse.com, phil@raspberrypi.org,
        devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ARM: dts: bcm2711: fix soc's node dma-ranges
Date:   Mon,  9 Dec 2019 10:12:56 -0800
Message-Id: <20191209181256.5854-1-f.fainelli@gmail.com>
In-Reply-To: <20191204125633.27696-1-nsaenzjulienne@suse.de>
References: <20191204125633.27696-1-nsaenzjulienne@suse.de>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed,  4 Dec 2019 13:56:33 +0100, Nicolas Saenz Julienne <nsaenzjulienne@suse.de> wrote:
> Raspberry Pi's firmware has a feature to select how much memory to
> reserve for its GPU called 'gpu_mem'. The possible values go from 16MB
> to 944MB, with a default of 64MB. This memory resides in the topmost
> part of the lower 1GB memory area and grows bigger expanding towards the
> begging of memory.
> 
> It turns out that with low 'gpu_mem' values (16MB and 32MB) the size of
> the memory available to the system in the lower 1GB area can outgrow the
> interconnect's dma-range as its size was selected based on the maximum
> system memory available given the default gpu_mem configuration. This
> makes that memory slice unavailable for DMA. And may cause nasty kernel
> warnings if CMA happens to include it.
> 
> Change soc's dma-ranges to really reflect it's HW limitation, which is
> being able to only DMA to the lower 1GB area.
> 
> Fixes: 7dbe8c62ceeb ("ARM: dts: Add minimal Raspberry Pi 4 support")
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> ---

Applied to devicetree/fixes, thanks!
--
Florian