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Date: Tue, 6 Feb 2024 19:08:40 +0100
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Subject: Re: [PATCH 02/12] bcm2835-dma: Add proper 40-bit DMA support
To: Dave Stevenson <dave.stevenson@raspberrypi.com>,
 Andrea della Porta <andrea.porta@suse.com>
Cc: 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, 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>
 <8736c115-e11c-41ca-85eb-7cd19a205068@gmx.net>
 <CAPY8ntCEvsTJwoEBYc7JsTaYfdMURhmytvvVMcLVNBkmdTNcZQ@mail.gmail.com>
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From: Stefan Wahren <wahrenst@gmx.net>
In-Reply-To: <CAPY8ntCEvsTJwoEBYc7JsTaYfdMURhmytvvVMcLVNBkmdTNcZQ@mail.gmail.com>
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Hi Dave and Andrea,

Am 06.02.24 um 17:31 schrieb Dave Stevenson:
> Hi Stefan and Andrea
>
> On Mon, 5 Feb 2024 at 18:50, Stefan Wahren <wahrenst@gmx.net> wrote:
>> 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?
> Yes, I'm looking at reworking Stefan's series to work on Pi4 & Pi5 as
> it's needed for HDMI audio (and other things) on those platforms which
> I'm working to upstream.
>
> I was getting weirdness from the sdhci block when I was last looking
> at it, so it was just proving a little trickier than first thought.
> Hopefully I'll get some time on it in the next couple of weeks.
i must confess that my series was just a draft to see that the general
approach would be accepted. Yes, it's possible that there are issues :-(

Maybe i can help you a little bit by taking care of first two patches
(node name fix & YAML conversion)?

Regards
>    Dave
>
>> [1] -
>> https://lore.kernel.org/linux-arm-kernel/13ec386b-2305-27da-9765-8fa3ad=
71146c@i2se.com/T/