linux-kernel - RE: [PATCH v2 6/7] dmaengine: sh: rz-dmac: Add RZ/V2H(P) support

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Message-ID:
 <TYCPR01MB1209386F83CD6407649A973F5C2FA2@TYCPR01MB12093.jpnprd01.prod.outlook.com>
Date: Tue, 18 Feb 2025 20:40:47 +0000
From: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
CC: Vinod Koul <vkoul@...nel.org>, Magnus Damm <magnus.damm@...il.com>,
	Philipp Zabel <p.zabel@...gutronix.de>, Wolfram Sang
	<wsa+renesas@...g-engineering.com>, Biju Das <biju.das.jz@...renesas.com>,
	Uwe Kleine-König <u.kleine-koenig@...libre.com>,
	"dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: RE: [PATCH v2 6/7] dmaengine: sh: rz-dmac: Add RZ/V2H(P) support

Hi Geert,

Thanks for your feedback!

> From: Geert Uytterhoeven <geert@...ux-m68k.org>
> Sent: 13 February 2025 14:23
> Subject: Re: [PATCH v2 6/7] dmaengine: sh: rz-dmac: Add RZ/V2H(P) support
> 
> Hi Fabrizio,
> 
> On Thu, 13 Feb 2025 at 15:19, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > On Wed, 12 Feb 2025 at 23:13, Fabrizio Castro
> > <fabrizio.castro.jz@...esas.com> wrote:
> > > The DMAC IP found on the Renesas RZ/V2H(P) family of SoCs is
> > > similar to the version found on the Renesas RZ/G2L family of
> > > SoCs, but there are some differences:
> > > * It only uses one register area
> > > * It only uses one clock
> > > * It only uses one reset
> > > * Instead of using MID/IRD it uses REQ NO/ACK NO
> > > * It is connected to the Interrupt Control Unit (ICU)
> > > * On the RZ/G2L there is only 1 DMAC, on the RZ/V2H(P) there are 5
> > >
> > > Add specific support for the Renesas RZ/V2H(P) family of SoC by
> > > tackling the aforementioned differences.
> > >
> > > Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> > > ---
> > > v1->v2:
> > > * Switched to new macros for minimum values.
> >
> > Thanks for the update!
> >
> > > --- a/drivers/dma/sh/Kconfig
> > > +++ b/drivers/dma/sh/Kconfig
> > > @@ -53,6 +53,7 @@ config RZ_DMAC
> > >         depends on ARCH_R7S72100 || ARCH_RZG2L || COMPILE_TEST
> > >         select RENESAS_DMA
> > >         select DMA_VIRTUAL_CHANNELS
> > > +       select RENESAS_RZV2H_ICU
> >
> > This enables RENESAS_RZV2H_ICU unconditionally, while it is only
> > really needed on RZ/V2H, and not on other arm64 SoCs, or on arm32
> > or riscv SoCs.
> 
> As ARCH_R9A09G057 already selects RENESAS_RZV2H_ICU, you could provide
> a dummy rzv2h_icu_register_dma_req_ack() for the !RENESAS_RZV2H_ICU
> case, or even disable all ICU-related code when it is not needed.

A dummy rzv2h_icu_register_dma_req_ack() sounds good, I'll include that
in the next version of the series.

Thanks!

Cheers,
Fab

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds