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SubjectRe: [PATCH v2] mfd: cros ec: Lock the SPI bus while holding chipselect
On Mon, 09 Nov 2015, Nicolas Boichat wrote:

> cros_ec_cmd_xfer_spi and cros_ec_pkt_xfer_spi generally work like
> this:
> - Pull CS down (active), wait a bit, then send a command
> - Wait for response (multiple requests)
> - Wait a while, pull CS up (inactive)
>
> These operations, individually, lock the SPI bus, but there is
> nothing preventing the SPI framework from interleaving messages
> intended for other devices as the bus is unlocked in between.
>
> This is a problem as the EC expects CS to be held low for the
> whole duration.
>
> Solution: Lock the SPI bus during the whole transaction, to make
> sure that no other messages can be interleaved.
>
> Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
> ---
>
> v2: Move bus_unlock earlier in the functions.
>
> Applies on top on linux-next/master (20151109)
>
> drivers/mfd/cros_ec_spi.c | 41 +++++++++++++++++++++++++++++------------
> 1 file changed, 29 insertions(+), 12 deletions(-)

Code changes look okay, but I think you can drop the comments.

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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