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Message-ID: <1af44c63f3fdffb3bb5d0cf718cc470ef8459c33.camel@physik.fu-berlin.de>
Subject: Re: [PATCH v2 3/3] sh: dma: Correct the number of DMA channels in
 SH7709
From:   John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Artur Rojek <contact@artur-rojek.eu>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>,
        Rafael Ignacio Zurita <rafaelignacio.zurita@gmail.com>,
        linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Tue, 04 Jul 2023 09:43:00 +0200
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Hi Geert!

On Tue, 2023-07-04 at 09:32 +0200, Geert Uytterhoeven wrote:
> Hi Adrian,
> 
> On Tue, Jul 4, 2023 at 7:45 AM John Paul Adrian Glaubitz
> <glaubitz@physik.fu-berlin.de> wrote:
> > On Sat, 2023-06-17 at 13:09 +0200, Geert Uytterhoeven wrote:
> > > On Sat, Jun 17, 2023 at 9:32 AM John Paul Adrian Glaubitz
> > > <glaubitz@physik.fu-berlin.de> wrote:
> > > > On Thu, 2023-06-08 at 12:03 +0200, John Paul Adrian Glaubitz wrote:
> > > > > > > > That is actually safer, as the user can override NR_ONCHIP_DMA_CHANNELS
> > > > > > > > when configuring his kernel, thus breaking DMA  due to an incorrect
> > > > > > > > value of SH_DMAC_NR_MD_CH.
> > > > > > > > 
> > > > > > > > Unfortunately we cannot protect against that when using a single DMAC,
> > > > > > > > as SH_DMAC_NR_MD_CH can be either 4, 6, or 8.
> > > > > > > > 
> > > > > > > > Perhaps this configuration should be moved from Kconfig to <cpu/dma.h>,
> > > > > > > > to protect against a user overriding this value?
> > > > > > > 
> > > > > > > Isn't SH_DMAC_NR_MD_CH already hardwired to the SoC being used?
> > > > > > 
> > > > > > It depends on CONFIG_NR_ONCHIP_DMA_CHANNELS, while it
> > > > > > should be fixed based on the SoC.
> > > > > 
> > > > > I agree. However, I would be fine with merging this patch set first and fixing
> > > > > this particular issue in a follow-up series.
> > > > 
> > > > So, my suggestion is to take this series as-is for 6.5, then get the other issues
> > > > you mentioned fixed for 6.6. I think it's already a gain when these issues are
> > > > fixed and the kernel boots on the HP Journada 680 again.
> > > 
> > > Sure, I don't want to block the acceptance of this series at all.
> > > Thanks!
> > 
> > Apologies for the late reply. Would you mind adding your Reviewed-by to this patch
> > before I review and apply the series?
> 
> With "must be a multiply of two" and "Must be an even number" removed.
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Thanks. I guess, I will drop the whole

	"and clarify that NR_ONCHIP_DMA_CHANNELS must be a multiply of two"

then. Correct?

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer
`. `'   Physicist
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