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Message-ID: <b09ad222-f5b8-af5a-6c2b-2dd6b30f1c73@ti.com>
Date: Tue, 4 Feb 2020 08:52:37 +0200
From: Peter Ujfalusi <peter.ujfalusi@...com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>,
John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
CC: Andy Shevchenko <andy.shevchenko@...il.com>,
Vinod Koul <vkoul@...nel.org>,
dmaengine <dmaengine@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Dan Williams <dan.j.williams@...el.com>,
Linux-sh list <linux-sh@...r.kernel.org>,
Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH 0/3] dmaengine: Stear users towards
dma_request_slave_chan()
Hi Geert, Adrian,
On 03/02/2020 22.34, Geert Uytterhoeven wrote:
> Hi Adrian,
>
> On Mon, Feb 3, 2020 at 9:21 PM John Paul Adrian Glaubitz
> <glaubitz@...sik.fu-berlin.de> wrote:
>> On 2/3/20 2:32 PM, Geert Uytterhoeven wrote:
>>> Both rspi and sh-msiof have users on legacy SH (i.e. without DT):
>>
>> FWIW, there is a patch set by Yoshinori Sato to add device tree support
>> for classical SuperH hardware. It was never merged, unfortunately :(.
>
> True.
>
>>> Anyone who cares for DMA on SuperH?
>>
>> What is DMA used for on SuperH? Wouldn't dropping it cut support for
>> essential hardware features?
>
> It may make a few things slower.
I would not drop DMA support but I would suggest to add dma_slave_map
for non DT boot so the _compat() can be dropped.
Imho on lower spec SoC (and I believe SuperH is) the DMA makes big
difference offloading data movement from the CPU.
> Does any of your SuperH boards use DMA?
> Anything interesting in /proc or /sys w.r.t. DMA?
>
> Gr{oetje,eeting}s,
>
> Geert
>
- Péter
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
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