Hi, Ben Dooks wrote on 2011-11-24: > 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? The old driver was marked as broken for the above reasons and I can hardly imagine any setup in which it would be preferable to i2c-gpio. So it does not make any sense to keep the old driver alive. Though inspired by the old driver, the new one is almost a rewrite from scratch, so for better reviewing, I removed the old instead of doing a diff. Niko -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
