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Date:   Tue, 19 Jul 2022 21:23:36 +0900
From:   Stafford Horne <shorne@gmail.com>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Christoph Hellwig <hch@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Richard Weinberger <richard@nod.at>,
        Anton Ivanov <anton.ivanov@cambridgegreys.com>,
        Johannes Berg <johannes@sipsolutions.net>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-csky@vger.kernel.org,
        linux-riscv <linux-riscv@lists.infradead.org>,
        linux-um <linux-um@lists.infradead.org>,
        linux-pci <linux-pci@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it
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On Tue, Jul 19, 2022 at 01:55:03PM +0200, Arnd Bergmann wrote:
> On Tue, Jul 19, 2022 at 12:55 PM Stafford Horne <shorne@gmail.com> wrote:
> 
> > diff --git a/drivers/comedi/drivers/comedi_isadma.c b/drivers/comedi/drivers/comedi_isadma.c
> > index 700982464c53..508421809128 100644
> > --- a/drivers/comedi/drivers/comedi_isadma.c
> > +++ b/drivers/comedi/drivers/comedi_isadma.c
> > @@ -104,8 +104,10 @@ unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
> >
> >         flags = claim_dma_lock();
> >         clear_dma_ff(desc->chan);
> > +#ifdef CONFIG_X86_32
> >         if (!isa_dma_bridge_buggy)
> >                 disable_dma(desc->chan);
> > +#endif
> 
> There is a logic mistake here: if we are on something other than x86-32,
> this always needs to call the disable_dma()/enable_dma().

Oops, thats right.  Sorry, I should have noticed that.

> Not sure how to best express this in a readable way, something like this
> would work:

Option 1:

> #ifdef CONFIG_X86_32
>         if (!isa_dma_bridge_buggy)
> #endif
>                disable_dma(desc->chan);
> 
> 
> or possibly at the start of this file, a

Option 2:

> #ifndef CONFIG_X86_32
> #define isa_dma_bridge_buggy 0
> #endif

Option 3:

> Or we could try to keep the generic definition in a global header
> like linux/isa-dma.h.

Perhaps option 3 makes the whole patch the most clean.

-Stafford