Hi Wolfram,
On Tue, Jun 6, 2017 at 1:23 PM, Wolfram Sang wrote:
>> I have it enabled all the time. So my devices may stop working...
>
> If you have enabled it all the time, then there won't be a difference
> from now. Or?
>
> That also shows how rarely I2C DMA transfers are triggered from within
> I have it enabled all the time. So my devices may stop working...
If you have enabled it all the time, then there won't be a difference
from now. Or?
That also shows how rarely I2C DMA transfers are triggered from within
the kernel :)
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Hi Wolfram,
On Tue, Jun 6, 2017 at 12:54 PM, Wolfram Sang wrote:
>> So it won't fall back to PIO if CONFIG_DMA_API_DEBUG is enabled?
>
> No, it will complain loudly with more details about the same things (and
> some more). But for that to do, it cannot fall back to PIO.
>
> Otherwise, you might
> So it won't fall back to PIO if CONFIG_DMA_API_DEBUG is enabled?
No, it will complain loudly with more details about the same things (and
some more). But for that to do, it cannot fall back to PIO.
Otherwise, you might get the idea that all is fine since you enabled
CONFIG_DMA_API_DEBUG but mi
Hi Wolfram,
On Tue, Jun 6, 2017 at 12:24 PM, Wolfram Sang wrote:
>> > +Therefore, it is *not* mandatory that the buffer of an i2c message is DMA
>> > safe.
>> > +It does not seem reasonable to apply additional burdens when the feature
>> > is so
>> > +rarely used. However, it is recommended to
> > +Therefore, it is *not* mandatory that the buffer of an i2c message is DMA
> > safe.
> > +It does not seem reasonable to apply additional burdens when the feature
> > is so
> > +rarely used. However, it is recommended to use a DMA-safe buffer, if your
> > +message size is likely applicable f
Hi Wolfram,
On Tue, Jun 6, 2017 at 11:20 AM, Wolfram Sang
wrote:
> --- /dev/null
> +++ b/Documentation/i2c/DMA-considerations
> @@ -0,0 +1,28 @@
> +Linux I2C and DMA
> +-
> +
> +Given that I2C is a low-speed bus where largely small messages are
> transferred,
> +it is not conside
Signed-off-by: Wolfram Sang
---
Documentation/i2c/DMA-considerations | 28
1 file changed, 28 insertions(+)
create mode 100644 Documentation/i2c/DMA-considerations
diff --git a/Documentation/i2c/DMA-considerations
b/Documentation/i2c/DMA-considerations
new file mod
