The minimum baud rate was hardcoded, not computed. A patch later in the
series will make use of the minimum baud rate as well.
The (1 + ((x - 1) / y)) pattern is to force rounding up (mathematically
the minimum rate is about 45.78bps).
Signed-off-by: Michael Hanselmann <public@xxxxxxxxx>
---
drivers/usb/serial/ch341.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 9407e12d9fbc..c820772e6a07 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -147,6 +147,8 @@ static int ch341_control_in(struct usb_device *dev,
#define CH341_CLKRATE 48000000
#define CH341_CLK_DIV(ps, fact) (1 << (12 - 3 * (ps) - (fact)))
+#define CH341_MIN_BPS \
+ (unsigned int)(1 + (((CH341_CLKRATE) - 1) / (CH341_CLK_DIV(0, 0) * 256)))
#define CH341_MIN_RATE(ps, fact) \
(CH341_CLKRATE / (CH341_CLK_DIV((ps), (fact)) * 256))
@@ -210,10 +212,10 @@ static int ch341_get_divisor(struct ch341_private *priv)
speed = priv->baud_rate;
/*
- * Clamp to supported range, this makes the (ps < 0) and (div < 2)
- * sanity checks below redundant.
+ * Clamp to supported range, making the later range sanity checks
+ * redundant.
*/
- speed = clamp(speed, 46U, 3000000U);
+ speed = clamp(speed, CH341_MIN_BPS, 3000000U);
if (priv->quirks & CH341_QUIRK_LIMITED_PRESCALER) {
/*
--
2.20.1
