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path: root/drivers/media/dvb-frontends/cx24123.c
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Diffstat (limited to 'drivers/media/dvb-frontends/cx24123.c')
-rw-r--r--drivers/media/dvb-frontends/cx24123.c28
1 files changed, 7 insertions, 21 deletions
diff --git a/drivers/media/dvb-frontends/cx24123.c b/drivers/media/dvb-frontends/cx24123.c
index 68c88ab58e71..a771da3e9f99 100644
--- a/drivers/media/dvb-frontends/cx24123.c
+++ b/drivers/media/dvb-frontends/cx24123.c
@@ -26,6 +26,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
+#include <asm/div64.h>
#include "dvb_frontend.h"
#include "cx24123.h"
@@ -452,7 +453,8 @@ static u32 cx24123_int_log2(u32 a, u32 b)
static int cx24123_set_symbolrate(struct cx24123_state *state, u32 srate)
{
- u32 tmp, sample_rate, ratio, sample_gain;
+ u64 tmp;
+ u32 sample_rate, ratio, sample_gain;
u8 pll_mult;
/* check if symbol rate is within limits */
@@ -482,27 +484,11 @@ static int cx24123_set_symbolrate(struct cx24123_state *state, u32 srate)
sample_rate = pll_mult * XTAL;
- /*
- SYSSymbolRate[21:0] = (srate << 23) / sample_rate
-
- We have to use 32 bit unsigned arithmetic without precision loss.
- The maximum srate is 45000000 or 0x02AEA540. This number has
- only 6 clear bits on top, hence we can shift it left only 6 bits
- at a time. Borrowed from cx24110.c
- */
-
- tmp = srate << 6;
- ratio = tmp / sample_rate;
-
- tmp = (tmp % sample_rate) << 6;
- ratio = (ratio << 6) + (tmp / sample_rate);
-
- tmp = (tmp % sample_rate) << 6;
- ratio = (ratio << 6) + (tmp / sample_rate);
-
- tmp = (tmp % sample_rate) << 5;
- ratio = (ratio << 5) + (tmp / sample_rate);
+ /* SYSSymbolRate[21:0] = (srate << 23) / sample_rate */
+ tmp = ((u64)srate) << 23;
+ do_div(tmp, sample_rate);
+ ratio = (u32) tmp;
cx24123_writereg(state, 0x01, pll_mult * 6);