From: Vinod Koul <vkoul@kernel.org>
To: Rob Herring <robh@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
devicetree@vger.kernel.org, CC Hwang <cc.hwang@mediatek.com>,
wsd_upstream <wsd_upstream@mediatek.com>,
Sean Wang <sean.wang@mediatek.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
EastL <EastL.Lee@mediatek.com>,
"open list:DMA GENERIC OFFLOAD ENGINE SUBSYSTEM"
<dmaengine@vger.kernel.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v8 1/4] dt-bindings: dmaengine: Add MediaTek Command-Queue DMA controller bindings
Date: Tue, 12 Jan 2021 17:43:33 +0530 [thread overview]
Message-ID: <20210112121333.GQ2771@vkoul-mobl> (raw)
In-Reply-To: <CAL_JsqLjgJUNJiE8uri9MKqTdik=7BBGP9bZSkD1mF+Sk3YfmQ@mail.gmail.com>
On 06-01-21, 16:53, Rob Herring wrote:
> > > > + dma-channel-mask:
> > > > + description:
> > > > + For DMA capability, We will know the addressing capability of
> > > > + MediaTek Command-Queue DMA controller through dma-channel-mask.
> > > > + minimum: 1
> > > > + maximum: 63
> > >
> > > Indentation is wrong here so this has no effect.
> > I'll fix it
> > >
> > > A mask of 63 is 6 channels...
> > In my opinion, kernel dma mask if for 32/64 bit capability...
> > If I don't set dma mask I will get fail on DMATEST.
>
> As in the kernel's 'dma_mask'? That's something entirely different.
> The driver should set the mask to the max the device supports.
> Typically this is a 32-bit or 64-bit mask. The default is 32-bit. If
> the SoC has limitations in its buses, then you need to use
> 'dma-ranges' in DT which will in turn set the bus_dma_limit.
Correct, dma_mask tells dmatest the capability of the device and should
be set accordingly
dma-channel-mask defines the 'Bitmask of available DMA channels' and is
deined in dma-common.yaml
--
~Vinod
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next prev parent reply other threads:[~2021-01-12 12:15 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-23 9:30 [PATCH v8] dmaengine: mediatek-cqdma: add dt-bindings and remove redundant queue EastL Lee
2020-12-23 9:30 ` [PATCH v8 1/4] dt-bindings: dmaengine: Add MediaTek Command-Queue DMA controller bindings EastL Lee
2021-01-03 16:58 ` Rob Herring
2021-01-06 9:25 ` EastL
2021-01-06 23:53 ` Rob Herring
2021-01-12 12:13 ` Vinod Koul [this message]
2020-12-23 9:30 ` [PATCH v8 2/4] dmaengine: mediatek-cqdma: remove redundant queue structure EastL Lee
2021-01-12 12:10 ` Vinod Koul
2020-12-23 9:30 ` [PATCH v8 3/4] dmaengine: mediatek-cqdma: add dma mask for capability EastL Lee
2020-12-23 9:30 ` [PATCH v8 4/4] dmaengine: mediatek-cqdma: fix compatible EastL Lee
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