linux-kernel - Re: [PATCH 4/5] dma-direct: implement complete bus_dma

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Message-ID: <b87ef7ac-81fc-c649-7ffb-73017ec99790@arm.com>
Date:   Thu, 27 Sep 2018 17:41:36 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Christoph Hellwig <hch@....de>
Cc:     iommu@...ts.linux-foundation.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 4/5] dma-direct: implement complete bus_dma_mask handling

On 27/09/18 17:27, Christoph Hellwig wrote:
> On Thu, Sep 27, 2018 at 05:14:56PM +0100, Robin Murphy wrote:
>>> This just seemed more readable to me than min_not_zero, but if others
>>> prefer min_not_zero I can switch.
>>
>> Nah, just checking whether there were any intentionally different
>> assumptions compared to the couple of other places in the patch where
>> min_not_zero() *is* used. If it's purely a style thing then no worries
>> (personally I'd have written it yet another way anyway).
> 
> I'm curious: how would you have written it?

Come to think of it, I actually already have, in iommu-dma:

	if (dev->bus_dma_mask)
		mask &= dev->bus_dma_mask;

but of course it's not so pretty for those cases where you don't already 
have the local variable ready to go.

Robin.