Re: [PATCH] staging: gasket: Fix sparse "incorrect type in assignment" warnings.

[Greg Kroah-Hartman]

On Thu, Oct 04, 2018 at 06:52:25PM +0100, Laurence Rochfort wrote:
> Silence the below sparse warnings by casting betwen u8 __iomem *, and
> void *.
> 
> warning: incorrect type in assignment (different address spaces)
>    expected unsigned char [noderef] [usertype] <asn:2>*virt_base
>    got void *[assigned] mem
> warning: incorrect type in argument 3 (different address spaces)
>    expected void *cpu_addr
>    got unsigned char [noderef] [usertype] <asn:2>*virt_base
> 
> Signed-off-by: Laurence Rochfort <laurence.rochfort@xxxxxxxxx>
> ---
>  drivers/staging/gasket/gasket_page_table.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/staging/gasket/gasket_page_table.c b/drivers/staging/gasket/gasket_page_table.c
> index d4c5f8a..7f5e5b3 100644
> --- a/drivers/staging/gasket/gasket_page_table.c
> +++ b/drivers/staging/gasket/gasket_page_table.c
> @@ -1278,7 +1278,7 @@ int gasket_alloc_coherent_memory(struct gasket_dev *gasket_dev, u64 size,
>  				 dma_addr_t *dma_address, u64 index)
>  {
>  	dma_addr_t handle;
> -	void *mem;
> +	u8 __iomem *mem;
>  	int j;
>  	unsigned int num_pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
>  	const struct gasket_driver_desc *driver_desc =
> @@ -1290,7 +1290,7 @@ int gasket_alloc_coherent_memory(struct gasket_dev *gasket_dev, u64 size,
>  	if (num_pages == 0)
>  		return -EINVAL;
>  
> -	mem = dma_alloc_coherent(gasket_get_device(gasket_dev),
> +	mem = (u8 __iomem *)dma_alloc_coherent(gasket_get_device(gasket_dev),
>  				 num_pages * PAGE_SIZE, &handle, 0);
>  	if (!mem)
>  		goto nomem;
> @@ -1325,7 +1325,7 @@ int gasket_alloc_coherent_memory(struct gasket_dev *gasket_dev, u64 size,
>  nomem:
>  	if (mem) {
>  		dma_free_coherent(gasket_get_device(gasket_dev),
> -				  num_pages * PAGE_SIZE, mem, handle);
> +				  num_pages * PAGE_SIZE, (void __force *)mem, handle);
>  	}
>  
>  	if (gasket_dev->page_table[index]->coherent_pages) {
> @@ -1353,7 +1353,7 @@ int gasket_free_coherent_memory(struct gasket_dev *gasket_dev, u64 size,
>  	if (gasket_dev->coherent_buffer.length_bytes) {
>  		dma_free_coherent(gasket_get_device(gasket_dev),
>  				  gasket_dev->coherent_buffer.length_bytes,
> -				  gasket_dev->coherent_buffer.virt_base,
> +				  (void __force *)gasket_dev->coherent_buffer.virt_base,

We should not have to "force" anything here.  Something feels wrong in
the definition of these variable types...

thanks,

greg k-h