[U-Boot] [PATCH v2 0/4] ARMV7: OMAP: I2C driver: Restructure code to eliminate udelay calls and improve performance

[Heiko Schocher]

Hello Steve,

Steve Sakoman wrote:
> I've been preparing a patch series for Beagle and Overo that detects expansion
> board configuration information by reading a 128 byte I2C EEPROM on each
> expansion board.
> 
> Using the OMAP I2C driver in its current form takes about 5-6 seconds to read
> this small number of bytes!  Executing the i2c probe command takes close
> to 10 seconds.
> 
> Examining the code I see that there are a large number of fairly long udelay calls
> throughout the driver (10 - 50 milliseconds). I looked through the linux driver
> and did not see equivalent delays in that code.  In fact the longest delay in the
> linux code was one millisecond.
> 
> In looking at the TRM I2C section for OMAP3 and OMAP4 I don't see any requirement
> for delays in the programming model description.
> 
> This patch restructures the i2c driver to eliminate most of the udelay calls
> by monitoring state changes in the status register.
> 
> The EEPROM reads and the i2c probe execution are now instantaneous.
> 
> This patch series was tested on OMAP3 (Overo) and OMAP4 (Panda).  I do not
> have access to OMAP2 hardware for testing.
> 
> Steve Sakoman (4):
>   ARMV7: OMAP: I2C driver: Use same timeout value as linux kernel
>     driver
>   ARMV7: OMAP: I2C driver: Restructure i2c_read_byte function
>   ARMV7: OMAP: I2C driver: Restructure i2c_write_byte function
>   ARMV7: OMAP: I2C driver: Restructure i2c_probe function
> 
>  drivers/i2c/omap24xx_i2c.c |  204 ++++++++++++++++++++++++-------------------
>  1 files changed, 114 insertions(+), 90 deletions(-)

Applied v2 to u-boot-i2c.git master

Thanks!

bye,
Heiko
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