Re: [PATCH v7 0/5] AT91: replace broken TWI driver i2c-at91.c

[Ben Dooks <ben-i2c@fluff.org>]

On Wed, Nov 23, 2011 at 04:35:55PM +0100, Nikolaus Voss wrote:
> The old driver has two main deficencies:
> i)  No repeated start (Sr) condiction is possible, this makes it unusable
>     e.g. for most SMBus transfers.
> ii) I/O was done with polling/busy waiting what caused over-/underruns
>     even at light system loads and clock speeds.
> 
> The new driver overcomes these deficencies and in addition allows for
> more than one TWI interface.
> 
> A remaining limitation is the fact, that only one repeated start is
> possible (two concatenated messages). This limitation is imposed by
> the hardware. However, this should not be a problem as all common
> i2c-client communication does not rely on more than one repeated start.
> 
> v7: Patch 4/5: i)  fix bug if internal address > 1 byte
>                ii) send stop when len == 1
>                    (both reported by Carsten Behling)
> v6: Patch 5/5: support for I2C_SMBUS_BLOCK_DATA transfers.
>     Better use of clk_(un)prepare().
>     More sensible transfer timeout.
> v5: Another round of review comments from Ryan Mallon, Felipe Balbi
>     and Russell King: convert twi clk to use .dev_id, cleanups
> v4: Integrated more review comments from Ryan Mallon and Felipe Balbi:
>     Moved register include file to local include, code cleanups
> v3: Integrated review comments from Ryan Mallon and Felipe Balbi
> v2: Fixed whitespace issue
> 
> Nikolaus Voss (5):
>   drivers/i2c/busses/i2c-at91.c: remove broken driver
>   Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk
>   drivers/i2c/busses/i2c-at91.c: add new driver
>   G45 TWI: remove open drain setting for twi function gpios
>   i2c-at91.c: add SMBUS_READ_BLOCK_DATA functionality

Is the original driver so broken that the two could not co-exist, or are
we making so many changes that there's no point in keeping the original
one?
 
>  arch/arm/mach-at91/at91cap9.c              |    1 +
>  arch/arm/mach-at91/at91rm9200.c            |    1 +
>  arch/arm/mach-at91/at91sam9260.c           |    1 +
>  arch/arm/mach-at91/at91sam9261.c           |    1 +
>  arch/arm/mach-at91/at91sam9263.c           |    1 +
>  arch/arm/mach-at91/at91sam9g45.c           |    2 +
>  arch/arm/mach-at91/at91sam9g45_devices.c   |    6 -
>  arch/arm/mach-at91/at91sam9rl.c            |    2 +
>  arch/arm/mach-at91/include/mach/at91_twi.h |   68 ----
>  drivers/i2c/busses/Kconfig                 |   11 +-
>  drivers/i2c/busses/i2c-at91.c              |  529 +++++++++++++++++-----------
>  drivers/i2c/busses/i2c-at91.h              |   80 +++++
>  12 files changed, 408 insertions(+), 295 deletions(-)
>  delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h
>  create mode 100644 drivers/i2c/busses/i2c-at91.h
> 
> -- 
> 1.7.5.4
> 
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-- 
Ben Dooks, ben@fluff.org, http://www.fluff.org/ben/

Large Hadron Colada: A large Pina Colada that makes the universe disappear.