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Date: Mon, 5 Feb 2024 19:50:44 +0100
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Subject: Re: [PATCH 02/12] bcm2835-dma: Add proper 40-bit DMA support
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To: Andrea della Porta <andrea.porta@suse.com>, Vinod Koul
 <vkoul@kernel.org>, Florian Fainelli <florian.fainelli@broadcom.com>,
 Ray Jui <rjui@broadcom.com>, Scott Branden <sbranden@broadcom.com>,
 Broadcom internal kernel review list
 <bcm-kernel-feedback-list@broadcom.com>, dmaengine@vger.kernel.org,
 linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org,
 linux-kernel@vger.kernel.org, Dave Stevenson <dave.stevenson@raspberrypi.com>
Cc: Maxime Ripard <maxime@cerno.tech>, Dom Cobley <popcornmix@gmail.com>,
 Phil Elwell <phil@raspberrypi.com>
References: <cover.1706948717.git.andrea.porta@suse.com>
 <eeb94204c30c2182f5ffd3ec083c04399ecdee32.1706948717.git.andrea.porta@suse.com>
From: Stefan Wahren <wahrenst@gmx.net>
In-Reply-To: <eeb94204c30c2182f5ffd3ec083c04399ecdee32.1706948717.git.andrea.porta@suse.com>
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Hi Andrea,

[add Dave]

Am 04.02.24 um 07:59 schrieb Andrea della Porta:
> From: Phil Elwell <phil@raspberrypi.org>
>
> BCM2711 has 4 DMA channels with a 40-bit address range, allowing them
> to access the full 4GB of memory on a Pi 4.
>
> Cc: Phil Elwell <phil@raspberrypi.org>
> Cc: Maxime Ripard <maxime@cerno.tech>
> Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
mainlining isn't that simple by sending just the downstream patches to
the mailing list. In many cases there reasons why this hasn't been
upstreamed yet.

In my opinion just this feature is worth a separate patch series. In
2021 i already send an initial version, which tried to implement it in a
cleaner & maintainabler way [1]. In the meantime Dave Stevenson from
Raspberry Pi wrote that he also wanted to work on this. Maybe you want
to work on this together?

[1] -
https://lore.kernel.org/linux-arm-kernel/13ec386b-2305-27da-9765-8fa3ad711=
46c@i2se.com/T/