Re: Compilation error report for: drivers/firmware/qcom_scm.c:469:47: error: passing argument 3 of âdma_alloc_coherentâ from incompatible pointer type

[Benjamin Gaignard]

2018-01-30 14:25 GMT+01:00 Arnd Bergmann <arnd@xxxxxxxx>:
> On Tue, Jan 30, 2018 at 11:11 AM, Benjamin GAIGNARD
> <benjamin.gaignard@xxxxxx> 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

>
>      Arnd