Messages in this thread | | | Date | Mon, 22 Apr 2013 15:52:39 -0500 | From | Jon Hunter <> | Subject | Re: [PATCH 2/2] dma: of: Remove check on always true condition |
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On 04/22/2013 03:33 AM, Lars-Peter Clausen wrote: > Both of_dma_nbcells field of the of_dma_controller and the args_count field of > the dma_spec are initialized by parsing the #dma-cells attribute of their device > tree node. So if the device tree nodes of a DMA controller and the dma_spec > match this means that of_dma_nbcells and args_count will also match. So the > second test in the of_dma_find_controller loop is redundant because given the > first test yields true the second test will also yield true. So we can safely > remove the test whether of_dma_nbcells matches args_count. Since this was the > last user of the of_dma_nbcells field we can remove it altogether.
This assumes that someone has correctly added the dma information to the dma slave binding. I could see systems where different dma controllers have different of_dma_nbcells and so someone could put the enter wrong number of cells for a dma slave binding. Its really to catch user error.
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> > --- > drivers/dma/of-dma.c | 14 +------------- > include/linux/of_dma.h | 1 - > 2 files changed, 1 insertion(+), 14 deletions(-) > > diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c > index 268cc8a..75334bd 100644 > --- a/drivers/dma/of-dma.c > +++ b/drivers/dma/of-dma.c > @@ -35,8 +35,7 @@ static struct of_dma *of_dma_find_controller(struct of_phandle_args *dma_spec) > struct of_dma *ofdma; > > list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers) > - if ((ofdma->of_node == dma_spec->np) && > - (ofdma->of_dma_nbcells == dma_spec->args_count)) > + if (ofdma->of_node == dma_spec->np) > return ofdma;
Other device-tree functions perform similar tests to this such as ...
static int of_gpiochip_find_and_xlate(struct gpio_chip *gc, void *data) { struct gg_data *gg_data = data; int ret;
if ((gc->of_node != gg_data->gpiospec.np) || (gc->of_gpio_n_cells != gg_data->gpiospec.args_count) || (!gc->of_xlate)) return false;
...
Cheers Jon
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