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x86/asm/tsc, staging/lirc_serial: Remove TSC-based timing 

It wasn't compiled in by default. I suspect that the driver was
and still is broken, though -- it's calling udelay with a
parameter that's derived from loops_per_jiffy.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Jarod Wilson <jarod@wilsonet.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: devel@driverdev.osuosl.org
Cc: kvm ML <kvm@vger.kernel.org>
Link: http://lkml.kernel.org/r/c95df47c5405b494d19d20b2852a9378c9f661f3.1434501121.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2015-06-25 18:44:03 +02:00 committed by Ingo Molnar
parent e18d1f8df1
commit 3a2c16c848
1 changed files with 4 additions and 59 deletions
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63
drivers/staging/media/lirc/lirc_serial.c
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@ -327,9 +327,6 @@ static void safe_udelay(unsigned long usecs)
* time
*/
/* So send_pulse can quickly convert microseconds to clocks */
static unsigned long conv_us_to_clocks;
static int init_timing_params(unsigned int new_duty_cycle,
unsigned int new_freq)
{
@ -344,7 +341,6 @@ static int init_timing_params(unsigned int new_duty_cycle,
/* How many clocks in a microsecond?, avoiding long long divide */
work = loops_per_sec;
work *= 4295; /* 4295 = 2^32 / 1e6 */
conv_us_to_clocks = work >> 32;
/*
* Carrier period in clocks, approach good up to 32GHz clock,
@ -357,10 +353,9 @@ static int init_timing_params(unsigned int new_duty_cycle,
pulse_width = period * duty_cycle / 100;
space_width = period - pulse_width;
dprintk("in init_timing_params, freq=%d, duty_cycle=%d, "
"clk/jiffy=%ld, pulse=%ld, space=%ld, "
"conv_us_to_clocks=%ld\n",
"clk/jiffy=%ld, pulse=%ld, space=%ld\n",
freq, duty_cycle, __this_cpu_read(cpu_info.loops_per_jiffy),
pulse_width, space_width, conv_us_to_clocks);
pulse_width, space_width);
return 0;
}
#else /* ! USE_RDTSC */
@ -431,63 +426,14 @@ static long send_pulse_irdeo(unsigned long length)
return ret;
}
#ifdef USE_RDTSC
/* Version that uses Pentium rdtsc instruction to measure clocks */
/*
* This version does sub-microsecond timing using rdtsc instruction,
* and does away with the fudged LIRC_SERIAL_TRANSMITTER_LATENCY
* Implicitly i586 architecture... - Steve
*/
static long send_pulse_homebrew_softcarrier(unsigned long length)
{
int flag;
unsigned long target, start, now;
/* Get going quick as we can */
rdtscl(start);
on();
/* Convert length from microseconds to clocks */
length *= conv_us_to_clocks;
/* And loop till time is up - flipping at right intervals */
now = start;
target = pulse_width;
flag = 1;
/*
* FIXME: This looks like a hard busy wait, without even an occasional,
* polite, cpu_relax() call. There's got to be a better way?
*
* The i2c code has the result of a lot of bit-banging work, I wonder if
* there's something there which could be helpful here.
*/
while ((now - start) < length) {
/* Delay till flip time */
do {
rdtscl(now);
} while ((now - start) < target);
/* flip */
if (flag) {
rdtscl(now);
off();
target += space_width;
} else {
rdtscl(now); on();
target += pulse_width;
}
flag = !flag;
}
rdtscl(now);
return ((now - start) - length) / conv_us_to_clocks;
}
#else /* ! USE_RDTSC */
/* Version using udelay() */
/*
* here we use fixed point arithmetic, with 8
* fractional bits. that gets us within 0.1% or so of the right average
* frequency, albeit with some jitter in pulse length - Steve
*
* This should use ndelay instead.
*/
/* To match 8 fractional bits used for pulse/space length */
@ -520,7 +466,6 @@ static long send_pulse_homebrew_softcarrier(unsigned long length)
}
return (actual-length) >> 8;
}
#endif /* USE_RDTSC */
static long send_pulse_homebrew(unsigned long length)
{