Re: [PATCH 3/4] devicetree: bindings: Add defeature-repeated-start property for Cadence I2C
From: Mark Rutland
Date: Tue Dec 02 2014 - 06:19:22 EST
On Tue, Dec 02, 2014 at 10:05:48AM +0000, Harini Katakam wrote:
> From: Vishnu Motghare <vishnum@xxxxxxxxxx>
> This patch adds "defeature-repeated-start" property in i2c-cadence.txt.
> Signed-off-by: Vishnu Motghare <vishnum@xxxxxxxxxx>
> Signed-off-by: Harini Katakam <harinik@xxxxxxxxxx>
> .../devicetree/bindings/i2c/i2c-cadence.txt | 11 +++++++++++
> 1 file changed, 11 insertions(+)
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-cadence.txt b/Documentation/devicetree/bindings/i2c/i2c-cadence.txt
> index 7cb0b56..9d417a7 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-cadence.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-cadence.txt
> @@ -11,6 +11,17 @@ Required properties:
> Optional properties:
> - clock-frequency: Desired operating frequency, in Hz, of the bus.
> - clock-names: Input clock name, should be 'pclk'.
> + - defeature-repeated-start: Include this property to defeature repeated start
> + This defeature is due to a few bugs in the
> + I2C controller.
> + Completion interrupt after a read/receive
> + operation is NOT obtained if HOLD bit is set
> + at that time. Because of this bug, repeated start
> + will only work if there are no transfers following
> + a read/receive transfer.
> + If HOLD is held for long without a transfer,
> + invalid read transactions are generated by the
> + controller due to a HW timeout related bug.
I'm not keen on the name; it sounds like we're disabling a feature
rather than describing the problem (and "defeature" is not a common
term in this sense, "disable" would be better).
It sounds like there are two issues with staying in the HOLD state? Lost
completion IRQs and a separate HW timeout bug? Or are the two related?
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