]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commit
i2c-designware: Divide i2c_dw_xfer_msg into two functions
authorShinya Kuribayashi <shinya.kuribayashi@necel.com>
Fri, 6 Nov 2009 12:48:55 +0000 (21:48 +0900)
committerBen Dooks <ben-linux@fluff.org>
Wed, 9 Dec 2009 00:19:11 +0000 (00:19 +0000)
commit81e798b73aec2d7ce06d18bd191b088c233e554f
tree4f3121a1708f0632cfec4d750dc064171e987dcf
parent21a89d4101ce338c2872401c82b66a7c155e24ab
i2c-designware: Divide i2c_dw_xfer_msg into two functions

We have some steps at the top of i2c_dw_xfer_msg() to set up a slave
address and enable DW I2C core.  And it's executed only when we don't
have STATUS_WRITE_IN_PROGRESS.

But we need to make sure that STATUS_WRITE_IN_PROGRESS only indicates
that we have a pending i2c_msg to process.  In other words, even if
STATUS_WRITE_IN_PROGRESS is not set, that doesn't mean we're at initial
state in the I2C transaction.

Since i2c_dw_xfer_msg() will be invoked again and again during a
transaction, those init steps have a possibility to be re-processed
needlessly.  For example, this issue easily takes place when processing
a combined transaction with a certain condition (the number of tx bytes
in the first i2c_msg, equals to the Tx FIFO depth).

Consequently we should not use STATUS_WRITE_IN_PROGRESS to determine
where we're at in an I2C transaction.  It would be better to separate
those initialization steps from i2c_dw_xfer_msg().

Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
drivers/i2c/busses/i2c-designware.c