[PATCH 2/2] pl011: factor our FIFO to TTY code

[Timur Tabi]

On Sat, Feb 19, 2011 at 2:17 PM, Linus Walleij
<linus.walleij at stericsson.com> wrote:
> +static int pl011_fifo_to_tty(struct uart_amba_port *uap)
> +{
> +       u16 status, ch;
> +       unsigned int flag, max_count = 256;
> +       int fifotaken = 0;
> +
> +       while (max_count--) {
> +               status = readw(uap->port.membase + UART01x_FR);
> +               if (status & UART01x_FR_RXFE)
> +                       break;
> +
> +               /* Take chars from the FIFO and update status */
> +               ch = readw(uap->port.membase + UART01x_DR) |
> +                       UART_DUMMY_DR_RX;

I know this patch is four years old, but I just noticed a bug, and I
can't figure out how no else noticed it.  Or maybe I'm imagining
things.

#define UART_DUMMY_DR_RX        (1 << 16)

UART_DUMMY_DR_RX cannot fit into 'ch', because ch is a 16-bit integer.
So the UART_DUMMY_DR_RX is lost.

What does UART_DUMMY_DR_RX do, anyway?  It's set in two places, but no
one ever checks for it.

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