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5200: improve i2c bus error recovery

PATCH Superseded Albrecht Dreß 4 participants 5 messages Jan 22, 2010 – Feb 16, 2010 Documentation

v1 of 2 Superseded Latest is v2 →

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PATCH 2/2 5200: improve i2c bus error recovery

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

---

Documentation/powerpc/dts-bindings/fsl/i2c.txt +1 -0
@@ -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.
 
 Examples :
 
#1 lore raw
Quoted 2 lines · Albrecht Dreß

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.

#2 lore raw

Am 25.01.10 08:55 schrieb(en) Wolfgang Grandegger:

Quoted 4 lines
Quoted 1 line · Albrecht Dreß

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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#3 lore raw
Quoted 5 lines · Albrecht Dreß

Am 25.01.10 08:55 schrieb(en) Wolfgang Grandegger:

Quoted 4 lines
Quoted 2 lines · Albrecht Dreß

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

Quoted 8 lines
Quoted 2 lines

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.

#4 lore raw
In reply to Albrecht Dreß
Quoted 10 lines · Albrecht Dreß

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

---

Documentation/powerpc/dts-bindings/fsl/i2c.txt 2010-01-22 16:04:56.000000000 +0100 renamed from Documentation/powerpc/dts-bindings/fsl/i2c.txt    2009-12-03 04:51:21.000000000 +0100 +0 -0
@@ -21,6 +21,7 @@
Quoted 4 lines

 - 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.

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

g.