[PATCH v2 3/3] ASoC: fsl_easrc: Use div64_u64 for 64-by-64 division

[wangdich9700]

From: wangdicheng <wangdicheng@xxxxxxxxxx>

Fix a coccinelle warning about do_div() truncating a 64-bit divisor:

sound/soc/fsl/fsl_easrc.c:2061:2-8: WARNING: do_div() does a 64-by-32 division, please consider using div64_u64 instead.

In fsl_easrc_m2m_calc_out_len(), val1 is computed as:

  val1 = (u64)in_rate << frac_bits;   // frac_bits up to 39
  do_div(val1, out_rate);
  val1 += (s64)ctx_priv->ratio_mod << (frac_bits - 31);
  val1 = val1 >> 12;

In the worst case (in_rate=384000, out_rate=8000, frac_bits=39):
  val1 = 384000 << 39 / 8000 = 26,388,279,068,672
  val1 >> 12 = 6,440,497,829  (33 bits, exceeds 32-bit range)

val1 is then used as the divisor in do_div(val2, val1), where
do_div() silently truncates it to 32 bits, producing incorrect
results. Use div64_u64() to perform a proper 64-by-64 division.

Fixes: 955ac624058f ("ASoC: fsl_easrc: Add EASRC ASoC CPU DAI drivers")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: wangdicheng <wangdicheng@xxxxxxxxxx>
---
 sound/soc/fsl/fsl_easrc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/soc/fsl/fsl_easrc.c b/sound/soc/fsl/fsl_easrc.c
index 114a6c0b6b73..d0bbe9f71e36 100644
--- a/sound/soc/fsl/fsl_easrc.c
+++ b/sound/soc/fsl/fsl_easrc.c
@@ -2058,7 +2058,7 @@ static int fsl_easrc_m2m_calc_out_len(struct fsl_asrc_pair *pair, int input_buff
 		/* right shift 12 bit to make ratio in 32bit space */
 		val2 = (u64)in_samples << (frac_bits - 12);
 		val1 = val1 >> 12;
-		do_div(val2, val1);
+		val2 = div64_u64(val2, val1);
 		out_samples = val2;
 
 		out_length = out_samples * out_width * channels;
-- 
2.25.1