linux-kernel - Re: [PATCH v2 3/3] sh: dma: Correct the number of DMA channels in SH7709

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Message-ID: <d5667e9675bf8be35b1a5414d443b8f371b1bd9e.camel@physik.fu-berlin.de>
Date:   Sat, 17 Jun 2023 09:31:57 +0200
From:   John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Artur Rojek <contact@...ur-rojek.eu>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        Rafael Ignacio Zurita <rafaelignacio.zurita@...il.com>,
        linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] sh: dma: Correct the number of DMA channels in
 SH7709

Hi Geert!

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.

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer
`. `'   Physicist
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913