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pwm: cros-ec: Add __packed to prevent padding

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While the particular usage in question is likely safe (struct
cros_ec_command is 32-bit aligned, followed by <= 32-bit fields), it's
been suggested this is not a great pattern to follow for the general
case -- for example, if we follow a 'struct cros_ec_command' (which is
32-bit- but not 64-bit-aligned) with a struct that starts with a 64-bit
type (e.g., u64), the compiler may add padding.

Let's add __packed, to inform the compiler of our true intention -- to
have no padding between these struct elements -- and to future proof for
any refactorings that might occur.

Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Brian Norris 2016-07-26 11:22:13 -07:00 committed by Thierry Reding
parent cd4b45ac44
commit 065cfbbb63
1 changed files with 2 additions and 2 deletions
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4
drivers/pwm/pwm-cros-ec.c
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@ -38,7 +38,7 @@ static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty)
struct {
struct cros_ec_command msg;
struct ec_params_pwm_set_duty params;
} buf;
} __packed buf;
struct ec_params_pwm_set_duty *params = &buf.params;
struct cros_ec_command *msg = &buf.msg;
@ -65,7 +65,7 @@ static int __cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index,
struct ec_params_pwm_get_duty params;
struct ec_response_pwm_get_duty resp;
};
} buf;
} __packed buf;
struct ec_params_pwm_get_duty *params = &buf.params;
struct ec_response_pwm_get_duty *resp = &buf.resp;
struct cros_ec_command *msg = &buf.msg;