[PATCH 02/12] bcm2835-dma: Add proper 40-bit DMA support

Stefan Wahren wahrenst at gmx.net
Tue Feb 6 10:11:37 PST 2024


Am 06.02.24 um 19:08 schrieb Stefan Wahren:
> 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 at gmx.net> wrote:
>>> Hi Andrea,
>>>
>>> [add Dave]
>>>
>>> Am 04.02.24 um 07:59 schrieb Andrea della Porta:
>>>> From: Phil Elwell <phil at 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 at raspberrypi.org>
>>>> Cc: Maxime Ripard <maxime at cerno.tech>
>>>> Signed-off-by: Andrea della Porta <andrea.porta at 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)?
Forget about this, it's already done
>
> Regards
>>    Dave
>>
>>> [1] -
>>> https://lore.kernel.org/linux-arm-kernel/13ec386b-2305-27da-9765-8fa3ad71146c@i2se.com/T/
>>>
>




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