From: VAMSHI GAJJELA <vamshigajjela@google.com>

uart_fifo_timeout() returns unsigned value, hence the function
uart_poll_timeout has been modified to use an unsigned int type for
timeout values instead of a signed int. The return type of the function
has been changed from int to unsigned int for consistency with the type
of timeout values. The result of uart_fifo_timeout() is cast to u32,
indicating that the value is truncated.

Signed-off-by: VAMSHI GAJJELA <vamshigajjela@google.com>
---
 include/linux/serial_core.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index b128513b009a..445a1ff7e502 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -773,9 +773,9 @@ static inline unsigned long uart_fifo_timeout(struct uart_port *port)
 }
 
 /* Base timer interval for polling */
-static inline int uart_poll_timeout(struct uart_port *port)
+static inline unsigned int uart_poll_timeout(struct uart_port *port)
 {
-	int timeout = uart_fifo_timeout(port);
+	unsigned int timeout = (u32)uart_fifo_timeout(port);
 
 	return timeout > 6 ? (timeout / 2 - 2) : 1;
 }
-- 
2.42.0.655.g421f12c284-goog

On Sat, 14 Oct 2023, Vamshi Gajjela wrote:

> From: VAMSHI GAJJELA <vamshigajjela@google.com>
> 
> uart_fifo_timeout() returns unsigned value, hence the function
> uart_poll_timeout has been modified to use an unsigned int type for
> timeout values instead of a signed int. The return type of the function
> has been changed from int to unsigned int for consistency with the type
> of timeout values. The result of uart_fifo_timeout() is cast to u32,
> indicating that the value is truncated.
> 
> Signed-off-by: VAMSHI GAJJELA <vamshigajjela@google.com>
> ---
>  include/linux/serial_core.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> index b128513b009a..445a1ff7e502 100644
> --- a/include/linux/serial_core.h
> +++ b/include/linux/serial_core.h
> @@ -773,9 +773,9 @@ static inline unsigned long uart_fifo_timeout(struct uart_port *port)
>  }
>  
>  /* Base timer interval for polling */
> -static inline int uart_poll_timeout(struct uart_port *port)
> +static inline unsigned int uart_poll_timeout(struct uart_port *port)

This is in jiffies so why don't you return unsigned long instead also 
here?

>  {
> -	int timeout = uart_fifo_timeout(port);
> +	unsigned int timeout = (u32)uart_fifo_timeout(port);

Use unsigned long and avoid casting entirely?
>  
>  	return timeout > 6 ? (timeout / 2 - 2) : 1;
>  }
> 

-- 
 i.