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From:   Arvind Sankar <nivedita@alum.mit.edu>
Date:   Mon, 7 Oct 2019 13:58:57 -0400
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Christoph Hellwig <hch@lst.de>,
        Arvind Sankar <nivedita@alum.mit.edu>,
        linux-kernel@vger.kernel.org
Subject: Re: ehci-pci breakage with dma-mapping changes in 5.4-rc2
Message-ID: <20191007175856.GA42018@rani.riverdale.lan>
References: <20191007022454.GA5270@rani.riverdale.lan>
 <20191007073448.GA882@lst.de>
 <20191007175430.GA32537@rani.riverdale.lan>
 <20191007175528.GA21857@lst.de>
 <20191007175630.GA28861@infradead.org>
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On Mon, Oct 07, 2019 at 10:56:30AM -0700, Christoph Hellwig wrote:
> On Mon, Oct 07, 2019 at 07:55:28PM +0200, Christoph Hellwig wrote:
> > On Mon, Oct 07, 2019 at 01:54:32PM -0400, Arvind Sankar wrote:
> > > It doesn't boot with the patch. Won't it go
> > > 	dma_get_required_mask
> > > 	-> intel_get_required_mask
> > > 	-> iommu_need_mapping
> > > 	-> dma_get_required_mask
> > > ?
> > > 
> > > Should the call to dma_get_required_mask in iommu_need_mapping be
> > > replaced with dma_direct_get_required_mask on top of your patch?
> > 
> > Yes, sorry.
> 
> Actually my patch already calls dma_direct_get_required_mask.
> How did you get the loop?

The function iommu_need_mapping (not changed by your patch) calls
dma_get_required_mask internally, to check whether the device's dma_mask
is big enough or not. That's the call I was asking whether it needs to
be changed.