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Date:   Mon, 22 Jul 2019 11:30:59 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Marc Gonzalez <marc.w.gonzalez@free.fr>
Cc:     Minwoo Im <minwoo.im.dev@gmail.com>,
        MSM <linux-arm-msm@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Andy Gross <agross@kernel.org>,
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        Stanimir Varbanov <svarbanov@mm-sol.com>,
        Rob Clark <robdclark@gmail.com>,
        Stephen Boyd <sboyd@kernel.org>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] firmware: qcom_scm: fix error for incompatible pointer
Message-ID: <20190722093059.GA29538@lst.de>
References: <20190719134303.7617-1-minwoo.im.dev@gmail.com> <7ea51e42-ab8a-e4e2-1833-651e2dabca3c@free.fr>
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On Mon, Jul 22, 2019 at 10:38:55AM +0200, Marc Gonzalez wrote:
> > In file included from drivers/firmware/qcom_scm.c:12:0:
> > ./include/linux/dma-mapping.h:636:21: note: expected ‘dma_addr_t * {aka long long unsigned int *}’ but argument is of type ‘phys_addr_t * {aka unsigned int *}’
> >  static inline void *dma_alloc_coherent(struct device *dev, size_t size,
> >                      ^~~~~~~~~~~~~~~~~~
> > ```
> > 
> > We just can cast phys_addr_t to dma_addr_t here.
> 
> IME, casting is rarely a proper solution.

*nod*

ptr_phys probably should be a dma_addr_t.  Unless this driver is so
magic that it really wants a physical and not a dma address, in which
case it needs to use alloc_pages instead of dma_alloc_coherent
and then call page_to_phys on the returned page, and a very big comment
explaining why it is so special.