Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <CA+M3ks4up-Xqwi8_HWn60O-iZsi4G8nX7TTfbOx32A2GN-rXOQ@mail.gmail.com>
References: <a2a6bf12-529c-cb20-c69f-106d34e1204a@st.com> <e804928d-deb9-668a-7012-2843ba85285e@st.com>
 <CAK8P3a36Kqh-qscU0vsKH00ReXKk8HOYzzhbt6SxAoEBvPYuig@mail.gmail.com> <CA+M3ks4up-Xqwi8_HWn60O-iZsi4G8nX7TTfbOx32A2GN-rXOQ@mail.gmail.com>
From:   Arnd Bergmann <arnd@arndb.de>
Date:   Tue, 30 Jan 2018 15:17:54 +0100
Message-ID: <CAK8P3a2UQ2xNs6R+YC8owEWQ-ooH=tuERa7Fs7acnkwi3N=FeA@mail.gmail.com>
Subject: =?UTF-8?Q?Re=3A_Compilation_error_report_for=3A_drivers=2Ffirmware=2Fq?=
        =?UTF-8?Q?com=5Fscm=2Ec=3A469=3A47=3A_error=3A_passing_argument_3_of_=E2=80=98dma=5Falloc=5F?=
        =?UTF-8?Q?coherent=E2=80=99_from_incompatible_pointer_type?=
To:     Benjamin Gaignard <benjamin.gaignard@linaro.org>
Cc:     Benjamin GAIGNARD <benjamin.gaignard@st.com>,
        Arnaud POULIQUEN <arnaud.pouliquen@st.com>,
        "Andy Gross <andy.gross@linaro.org> , David Brown" 
        <david.brown@linaro.org>,
        "linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
        "linux-soc@vger.kernel.org" <linux-soc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Jan 30, 2018 at 3:00 PM, Benjamin Gaignard
<benjamin.gaignard@linaro.org> wrote:
> 2018-01-30 14:25 GMT+01:00 Arnd Bergmann <arnd@arndb.de>:
>> On Tue, Jan 30, 2018 at 11:11 AM, Benjamin GAIGNARD
>> <benjamin.gaignard@st.com> wrote:
>>>
>>> On 01/12/2018 05:11 PM, Arnaud Pouliquen wrote:
>>>> Hello Andy,David,
>>> + Arnd
>>>
>>> I have the same issue on drm-misc-next.
>>> Does Arnaud's fix make sense or should we update/change the way of how
>>> we compile the kernel ?
>>
>> We've hit a couple of bugs with qcom drivers confusing physical addresses
>> and DMA addresses in the past, usually the drivers were buggy in
>> some form, and tried to use dma_alloc_coherent() to get a buffer
>> that gets passed into a firmware interface taking a physical address,
>> which is of course completely wrong.
>>
>>>> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
>>>> index af4c752..8dfbe61 100644
>>>> --- a/drivers/firmware/qcom_scm.c
>>>> +++ b/drivers/firmware/qcom_scm.c
>>>> @@ -448,7 +448,7 @@ int qcom_scm_assign_mem(phys_addr_t mem_addr, size_t
>>>> mem_sz,
>>>>       struct qcom_scm_mem_map_info *mem_to_map;
>>>>       phys_addr_t mem_to_map_phys;
>>>>       phys_addr_t dest_phys;
>>>> -     phys_addr_t ptr_phys;
>>>> +     dma_addr_t ptr_phys;
>>>>       size_t mem_to_map_sz;
>>>>       size_t dest_sz;
>>>>       size_t src_sz;
>>
>> This would be bad: you can basically never have a 'dma_addr_t ptr_phys': it can
>> be exactly one of 'dma address',  'physical address' or a pointer,
>> this claims that the
>> struct member is all three of them.
>>
>> The proper fix here is to stop using dma_alloc_coherent.
>
> Okay but that doesn't explain why we are the only ones to get an issue
> while the parameter
> doesn't match function prototype

For almost all configurations, dma_addr_t and phys_addr_t are the
same width, and gcc treats them as compatible.

I usually get the warning during randconfig builds, but you seem to
have started with a configuration like this.

        Arnd