RE: [PATCH 1/3] staging: comedi: work without HAS_DMA

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On Friday, May 10, 2013 6:07 AM, Ian Abbott wrote:
> The core "comedi" module and the "mite" helper module for NI PCI devices
> both have calls to `dma_alloc_coherent()` and `dma_free_coherent()`.
> Those functions are only available if `CONFIG_HAS_DMA` is defined.
>
> Apart from the "mite" module, the functions are only called for comedi
> drivers that set `s->async_dma_dir` (where `s` is a pointer to a `struct
> comedi_subdevice`) to anything other than `DMA_NONE`.
>
> Change local helper functions `__comedi_buf_alloc()` and
> `__comedi_buf_free()` to only call `dma_alloc_coherent()` and
> `dma_free_coherent()` if `CONFIG_HAS_DMA` is defined.
>
> Change the "Kconfig" to make the following configuration options depend
> on `HAS_DMA`:
>
> `COMEDI_MITE` - builds the "mite" module.
> `COMEDI_NI_6527` - selects `COMEDI_MITE`.
> `COMEDI_NI_65XX` - selects `COMEDI_MITE`.
> `COMEDI_NI_670X` - selects `COMEDI_MITE`.
> `COMEDI_NI_LABPC_PCI` - selects `COMEDI_MITE`.
> `COMEDI_NI_PCIDIO` - selects `COMEDI_MITE`.
> `COMEDI_NI_TIOCMD` - selects `COMEDI_MITE`.
> `COMEDI_NI_660X` - selects `COMEDI_NI_TIOCMD`,
>                    sets `s->async_dma_dir`.
> `COMEDI_NI_PCIMIO` - selects `COMEDI_NI_TIOCMD`,
>                      sets `s->async_dma_dir`.
>
> Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
> ---
>  drivers/staging/comedi/Kconfig      | 9 +++++++++
>  drivers/staging/comedi/comedi_buf.c | 6 ++++++
>  2 files changed, 15 insertions(+)
>
> diff --git a/drivers/staging/comedi/Kconfig b/drivers/staging/comedi/Kconfig
> index 7871579..87e852a 100644
> --- a/drivers/staging/comedi/Kconfig
> +++ b/drivers/staging/comedi/Kconfig
> @@ -981,6 +981,7 @@ config COMEDI_ME_DAQ
>  
>  config COMEDI_NI_6527
>  	tristate "NI 6527 support"
> +	depends on HAS_DMA
>  	select COMEDI_MITE
>  	---help---
>  	  Enable support for the National Instruments 6527 PCI card
> @@ -990,6 +991,7 @@ config COMEDI_NI_6527
>  
>  config COMEDI_NI_65XX
>  	tristate "NI 65xx static dio PCI card support"
> +	depends on HAS_DMA
>  	select COMEDI_MITE
>  	---help---
>  	  Enable support for National Instruments 65xx static dio boards.
> @@ -1003,6 +1005,7 @@ config COMEDI_NI_65XX
>  
>  config COMEDI_NI_660X
>  	tristate "NI 660x counter/timer PCI card support"
> +	depends on HAS_DMA
>  	select COMEDI_NI_TIOCMD
>  	---help---
>  	  Enable support for National Instruments PCI-6601 (ni_660x), PCI-6602,
> @@ -1013,6 +1016,7 @@ config COMEDI_NI_660X
>  
>  config COMEDI_NI_670X
>  	tristate "NI 670x PCI card support"
> +	depends on HAS_DMA
>  	select COMEDI_MITE
>  	---help---
>  	  Enable support for National Instruments PCI-6703 and PCI-6704
> @@ -1022,6 +1026,7 @@ config COMEDI_NI_670X
>  
>  config COMEDI_NI_LABPC_PCI
>  	tristate "NI Lab-PC PCI-1200 support"
> +	depends on HAS_DMA
>  	select COMEDI_NI_LABPC
>  	select COMEDI_MITE
>  	---help---
> @@ -1032,6 +1037,7 @@ config COMEDI_NI_LABPC_PCI
>  
>  config COMEDI_NI_PCIDIO
>  	tristate "NI PCI-DIO32HS, PCI-6533, PCI-6534 support"
> +	depends on HAS_DMA
>  	select COMEDI_MITE
>  	select COMEDI_8255
>  	---help---
> @@ -1043,6 +1049,7 @@ config COMEDI_NI_PCIDIO
>  
>  config COMEDI_NI_PCIMIO
>  	tristate "NI PCI-MIO-E series and M series support"
> +	depends on HAS_DMA
>  	select COMEDI_NI_TIOCMD
>  	select COMEDI_8255
>  	select COMEDI_FC
> @@ -1095,10 +1102,12 @@ config COMEDI_SSV_DNP
>  	  called ssv_dnp.
>  
>  config COMEDI_MITE
> +	depends on HAS_DMA
>  	tristate
>  
>  config COMEDI_NI_TIOCMD
>  	tristate
> +	depends on HAS_DMA
>  	select COMEDI_NI_TIO
>  	select COMEDI_MITE
>  
> diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c
> index ca70990..b6cd67a 100644
> --- a/drivers/staging/comedi/comedi_buf.c
> +++ b/drivers/staging/comedi/comedi_buf.c
> @@ -51,10 +51,12 @@ static void __comedi_buf_free(struct comedi_device *dev,
>  			clear_bit(PG_reserved,
>  				  &(virt_to_page(buf->virt_addr)->flags));
>  			if (s->async_dma_dir != DMA_NONE) {
> +#ifdef CONFIG_HAS_DMA
>  				dma_free_coherent(dev->hw_dev,
>  						  PAGE_SIZE,
>  						  buf->virt_addr,
>  						  buf->dma_addr);
> +#endif
>  			} else {
>  				free_page((unsigned long)buf->virt_addr);
>  			}
> @@ -84,11 +86,15 @@ static void __comedi_buf_alloc(struct comedi_device *dev,
>  	for (i = 0; i < n_pages; i++) {
>  		buf = &async->buf_page_list[i];
>  		if (s->async_dma_dir != DMA_NONE)
> +#ifdef CONFIG_HAS_DMA
>  			buf->virt_addr = dma_alloc_coherent(dev->hw_dev,
>  							    PAGE_SIZE,
>  							    &buf->dma_addr,
>  							    GFP_KERNEL |
>  							    __GFP_COMP);
> +#else
> +			break;
> +#endif

This break is unnecessary.

>  		else
>  			buf->virt_addr = (void *)get_zeroed_page(GFP_KERNEL);
>  		if (!buf->virt_addr)

'buf' is vzalloc'ed so buf->virt_addr will be NULL and the check above will do the break.

Regards,
Hartley

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