[PATCH/RFC 2/2] 5200: improve i2c bus error recovery

[PATCH/RFC 2/2] 5200: improve i2c bus error recovery

[Albrecht Dreß]

Make the I2C adapter timeout configurable through a Device Tree property
which gives the timeout in microseconds.

Signed-off-by: Albrecht Dre=DF <albrecht.dress@arcor.de>

---

--- linux-2.6.32-orig/Documentation/powerpc/dts-bindings/fsl/i2c.txt	2009-1=
2-03 04:51:21.000000000 +0100
+++ linux-2.6.32/Documentation/powerpc/dts-bindings/fsl/i2c.txt	2010-01-22 =
16:04:56.000000000 +0100
@@ -21,6 +21,7 @@
  - fsl,preserve-clocking : boolean; if defined, the clock settings
    from the bootloader are preserved (not touched).
  - clock-frequency : desired I2C bus clock frequency in Hz.
+ - timeout : I2C timeout in microseconds.
=20
 Examples :
=20

Re: [PATCH/RFC 2/2] 5200: improve i2c bus error recovery

[Wolfgang Grandegger]

Albrecht Dreß wrote:
> Make the I2C adapter timeout configurable through a Device Tree property
> which gives the timeout in microseconds.

My understanding is that software properties should not be defined via
the device tree. I think a sysfs entry is more appropriate.

Wolfgang.

Re: [PATCH/RFC 2/2] 5200: improve i2c bus error recovery

[Albrecht Dreß]

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Am 25.01.10 08:55 schrieb(en) Wolfgang Grandegger:
> Albrecht Dreß wrote:
>> Make the I2C adapter timeout configurable through a Device Tree property which gives the timeout in microseconds.
> 
> My understanding is that software properties should not be defined via the device tree. I think a sysfs entry is more appropriate.

Is the timeout really a /software/ property?  My feeling is that the timeout basically depends upon the bus clock and the chips attached to the bus.  Therefore, it is linked closer to the composition of the board's hardware as described in the device tree, than to any userland software.  Or am I totally wrong here?

Thanks, Albrecht.

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Re: [PATCH/RFC 2/2] 5200: improve i2c bus error recovery

[Wolfgang Grandegger]

Albrecht Dreß wrote:
> Am 25.01.10 08:55 schrieb(en) Wolfgang Grandegger:
>> Albrecht Dreß wrote:
>>> Make the I2C adapter timeout configurable through a Device Tree
>>> property which gives the timeout in microseconds.
>>
>> My understanding is that software properties should not be defined via
>> the device tree. I think a sysfs entry is more appropriate.
> 
> Is the timeout really a /software/ property?  My feeling is that the
> timeout basically depends upon the bus clock and the chips attached to
> the bus.  Therefore, it is linked closer to the composition of the
> board's hardware as described in the device tree, than to any userland
> software.  Or am I totally wrong here?

Well, yes, it seems to be a border case.

Wolfgang.

Re: [PATCH/RFC 2/2] 5200: improve i2c bus error recovery

[Grant Likely]

On Fri, Jan 22, 2010 at 1:18 PM, Albrecht Dre=DF <albrecht.dress@arcor.de> =
wrote:
> Make the I2C adapter timeout configurable through a Device Tree property
> which gives the timeout in microseconds.
>
> Signed-off-by: Albrecht Dre=DF <albrecht.dress@arcor.de>
>
> ---
>
> --- linux-2.6.32-orig/Documentation/powerpc/dts-bindings/fsl/i2c.txt =A0 =
=A02009-12-03 04:51:21.000000000 +0100
> +++ linux-2.6.32/Documentation/powerpc/dts-bindings/fsl/i2c.txt 2010-01-2=
2 16:04:56.000000000 +0100
> @@ -21,6 +21,7 @@
> =A0- fsl,preserve-clocking : boolean; if defined, the clock settings
> =A0 =A0from the bootloader are preserved (not touched).
> =A0- clock-frequency : desired I2C bus clock frequency in Hz.
> + - timeout : I2C timeout in microseconds.

fsl,timeout to avoid namespace collisions please (ie. if a common i2c
'timeout' property is ever defined for all i2c busses)

g.