linux-kernel - RE: [PATCH v3 7/9] arm64: dts: renesas: rzg3s-smarc-som: Update dma-ranges for PCIe

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Message-ID:
 <TY3PR01MB113467C09DF7D3D0D7833A6598649A@TY3PR01MB11346.jpnprd01.prod.outlook.com>
Date: Wed, 9 Jul 2025 05:05:44 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Claudiu.Beznea <claudiu.beznea@...on.dev>, "bhelgaas@...gle.com"
	<bhelgaas@...gle.com>, "lpieralisi@...nel.org" <lpieralisi@...nel.org>,
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	<krzk+dt@...nel.org>, "conor+dt@...nel.org" <conor+dt@...nel.org>,
	"geert+renesas@...der.be" <geert+renesas@...der.be>, "magnus.damm@...il.com"
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CC: "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-clk@...r.kernel.org"
	<linux-clk@...r.kernel.org>, Claudiu Beznea
	<claudiu.beznea.uj@...renesas.com>, Wolfram Sang
	<wsa+renesas@...g-engineering.com>
Subject: RE: [PATCH v3 7/9] arm64: dts: renesas: rzg3s-smarc-som: Update
 dma-ranges for PCIe

Hi Claudiu Beznea,

> -----Original Message-----
> From: Claudiu Beznea <claudiu.beznea@...on.dev>
> Sent: 08 July 2025 11:10
> Subject: Re: [PATCH v3 7/9] arm64: dts: renesas: rzg3s-smarc-som: Update dma-ranges for PCIe
> 
> Hi, Biju,
> 
> On 07.07.2025 11:18, Biju Das wrote:
> > Hi Claudiu,
> >
> >> -----Original Message-----
> >> From: Claudiu <claudiu.beznea@...on.dev>
> >> Sent: 04 July 2025 17:14
> >> Subject: [PATCH v3 7/9] arm64: dts: renesas: rzg3s-smarc-som: Update
> >> dma-ranges for PCIe
> >>
> >> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> >>
> >> The first 128MB of memory is reserved on this board for secure area.
> >> Update the PCIe dma-ranges property to reflect this.
> >
> > I see R-Car PCIe dma-ranges[1] and [2] maps all possible DDR area supported by the SoC?
> > Do we need to make board specific as well there?
> 
> I'm not familiar with R-Car, but if there are ranges reserved for other purposes, I think we should
> reflect it in board specific device trees.


Already Linux has this DDR info[1]. Linux provides DMA memory only from this region.

In your testing, have you faced any issue like system allocated DMA region other than [1]
and you don't want to use it, then the changes are ok??

Not sure, PCIe can work on internal memory such as SRAM?

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm64/boot/dts/renesas/rzg3s-smarc-som.dtsi?h=next-20250708#n31

Cheers,
Biju