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| author | Javier Martinez Canillas <javier.martinez@collabora.co.uk> | 2015-06-09 14:04:42 +0300 |
|---|---|---|
| committer | Lee Jones <lee.jones@linaro.org> | 2015-06-15 15:18:19 +0300 |
| commit | a841178445bb72a3d566b4e6ab9d19e9b002eb47 (patch) | |
| tree | bdc857e82c9c9e8b49bd5471efa5a954673d58f0 /include/linux/mfd/cros_ec.h | |
| parent | bb03ffb96c72418d06e75c7b74ea62e04c78d322 (diff) | |
| download | linux-a841178445bb72a3d566b4e6ab9d19e9b002eb47.tar.xz | |
mfd: cros_ec: Use a zero-length array for command data
Commit 1b84f2a4cd4a ("mfd: cros_ec: Use fixed size arrays to transfer
data with the EC") modified the struct cros_ec_command fields to not
use pointers for the input and output buffers and use fixed length
arrays instead.
This change was made because the cros_ec ioctl API uses that struct
cros_ec_command to allow user-space to send commands to the EC and
to get data from the EC. So using pointers made the API not 64-bit
safe. Unfortunately this approach was not flexible enough for all
the use-cases since there may be a need to send larger commands
on newer versions of the EC command protocol.
So to avoid to choose a constant length that it may be too big for
most commands and thus wasting memory and CPU cycles on copy from
and to user-space or having a size that is too small for some big
commands, use a zero-length array that is both 64-bit safe and
flexible. The same buffer is used for both output and input data
so the maximum of these values should be used to allocate it.
Suggested-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Diffstat (limited to 'include/linux/mfd/cros_ec.h')
| -rw-r--r-- | include/linux/mfd/cros_ec.h | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h index 14cf522123dd..7eee38abd02a 100644 --- a/include/linux/mfd/cros_ec.h +++ b/include/linux/mfd/cros_ec.h @@ -42,8 +42,7 @@ enum { * @outsize: Outgoing length in bytes * @insize: Max number of bytes to accept from EC * @result: EC's response to the command (separate from communication failure) - * @outdata: Outgoing data to EC - * @indata: Where to put the incoming data from EC + * @data: Where to put the incoming data from EC and outgoing data to EC */ struct cros_ec_command { uint32_t version; @@ -51,8 +50,7 @@ struct cros_ec_command { uint32_t outsize; uint32_t insize; uint32_t result; - uint8_t outdata[EC_PROTO2_MAX_PARAM_SIZE]; - uint8_t indata[EC_PROTO2_MAX_PARAM_SIZE]; + uint8_t data[0]; }; /** |