Re: [PATCH v2 10/17] input/joystick/analog: Switch from rdtscl() to native_read_tsc()

From: Dmitry Torokhov
Date: Tue Jun 16 2015 - 19:04:12 EST


On Fri, Jun 12, 2015 at 04:44:50PM -0700, Andy Lutomirski wrote:
> This timing code is hideous, and this doesn't help. It gets rid of
> one of the last users of rdtscl, though.
>
> Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> Cc: linux-input@xxxxxxxxxxxxxxx
> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>

Acked-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>

> ---
> drivers/input/joystick/analog.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/input/joystick/analog.c b/drivers/input/joystick/analog.c
> index 4284080e481d..f871b4f00056 100644
> --- a/drivers/input/joystick/analog.c
> +++ b/drivers/input/joystick/analog.c
> @@ -143,7 +143,7 @@ struct analog_port {
>
> #include <linux/i8253.h>
>
> -#define GET_TIME(x) do { if (cpu_has_tsc) rdtscl(x); else x = get_time_pit(); } while (0)
> +#define GET_TIME(x) do { if (cpu_has_tsc) x = (unsigned int)native_read_tsc(); else x = get_time_pit(); } while (0)
> #define DELTA(x,y) (cpu_has_tsc ? ((y) - (x)) : ((x) - (y) + ((x) < (y) ? PIT_TICK_RATE / HZ : 0)))
> #define TIME_NAME (cpu_has_tsc?"TSC":"PIT")
> static unsigned int get_time_pit(void)
> @@ -160,7 +160,7 @@ static unsigned int get_time_pit(void)
> return count;
> }
> #elif defined(__x86_64__)
> -#define GET_TIME(x) rdtscl(x)
> +#define GET_TIME(x) do { x = (unsigned int)native_read_tsc(); } while (0)
> #define DELTA(x,y) ((y)-(x))
> #define TIME_NAME "TSC"
> #elif defined(__alpha__) || defined(CONFIG_MN10300) || defined(CONFIG_ARM) || defined(CONFIG_ARM64) || defined(CONFIG_TILE)
> --
> 2.4.2
>

--
Dmitry
--
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