From: "Duc-Long, Le" <duclong.linux@gmail.com>
To: Mauro Carvalho Chehab <mchehab@kernel.org>,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] media: tc358746: fix the pll calculating function
Date: Sat, 14 Oct 2023 20:19:46 -0400 [thread overview]
Message-ID: <20231015001946.GA10485@fpga> (raw)
Following formula of Pll_clk in 5.2 section, 50th page of
TC358746AXBG/748XBG/748IXBG Functional Specification Rev 1.1 document.
The formula of fout is as below:
fout = refclk * mul / (prediv * postdiv)
Remove "p" to avoid using 2 times of prediv in pll calculating function.
Signed-off-by: Duc-Long, Le <duclong.linux@gmail.com>
---
drivers/media/i2c/tc358746.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/media/i2c/tc358746.c b/drivers/media/i2c/tc358746.c
index 566f5eaddd57..4f54773886cc 100644
--- a/drivers/media/i2c/tc358746.c
+++ b/drivers/media/i2c/tc358746.c
@@ -839,14 +839,14 @@ static unsigned long tc358746_find_pll_settings(struct tc358746 *tc358746,
if (fin < 4 * HZ_PER_MHZ || fin > 40 * HZ_PER_MHZ)
continue;
- tmp = fout * p * postdiv;
+ tmp = fout * postdiv;
do_div(tmp, fin);
mul = tmp;
if (mul > 511)
continue;
tmp = mul * fin;
- do_div(tmp, p * postdiv);
+ do_div(tmp, postdiv);
delta = abs(fout - tmp);
if (delta < min_delta) {
--
2.17.1
reply other threads:[~2023-10-15 0:19 UTC|newest]
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