In my haste I forgot the most important part of this patch, I'm sorry
Arnd.
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
On 2016-05-11 15:15:11 +0200, Niklas Söderlund wrote:
> Currently the following DT description would result in dmac0 always
> being tried first and dmac1 second if dmac0 was unavailable. This
> results in heavier use of dmac0 then of dmac1. This patch adds an
> approximate average distribution over the two nodes lessening the load
> of anyone of them.
>
> i2c6: i2c@e60b0000 {
> ...
> dmas = <&dmac0 0x77>, <&dmac0 0x78>,
> <&dmac1 0x77>, <&dmac1 0x78>;
> dma-names = "tx", "rx", "tx", "rx";
> ...
> };
>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> ---
> drivers/dma/of-dma.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
> index 1e1f298..faae0bf 100644
> --- a/drivers/dma/of-dma.c
> +++ b/drivers/dma/of-dma.c
> @@ -240,8 +240,9 @@ struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
> struct of_phandle_args dma_spec;
> struct of_dma *ofdma;
> struct dma_chan *chan;
> - int count, i;
> + int count, i, start;
> int ret_no_channel = -ENODEV;
> + static atomic_t last_index;
>
> if (!np || !name) {
> pr_err("%s: not enough information provided\n", __func__);
> @@ -259,8 +260,15 @@ struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
> return ERR_PTR(-ENODEV);
> }
>
> + /*
> + * approximate an average distribution across multiple
> + * entries with the same name
> + */
> + start = atomic_inc_return(&last_index);
> for (i = 0; i < count; i++) {
> - if (of_dma_match_channel(np, name, i, &dma_spec))
> + if (of_dma_match_channel(np, name,
> + (i + start) % count,
> + &dma_spec))
> continue;
>
> mutex_lock(&of_dma_lock);
> --
> 2.8.2
>
--
Regards,
Niklas Söderlund
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