Re: [PATCH v5 10/16] hw/char/pl011: Check if receiver is enabled

[Peter Maydell]

On Fri, 19 Jul 2024 at 19:11, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>
> Do not receive characters when UART or receiver are disabled.
>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  hw/char/pl011.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/hw/char/pl011.c b/hw/char/pl011.c
> index c76283dccf..0ce91c13d3 100644
> --- a/hw/char/pl011.c
> +++ b/hw/char/pl011.c
> @@ -85,6 +85,7 @@ DeviceState *pl011_create(hwaddr addr, qemu_irq irq, 
> Chardev *chr)
>  #define CR_OUT1     (1 << 12)
>  #define CR_RTS      (1 << 11)
>  #define CR_DTR      (1 << 10)
> +#define CR_RXE      (1 << 9)
>  #define CR_TXE      (1 << 8)
>  #define CR_LBE      (1 << 7)
>  #define CR_UARTEN   (1 << 0)
> @@ -481,9 +482,11 @@ static void pl011_write(void *opaque, hwaddr offset,
>  static int pl011_can_receive(void *opaque)
>  {
>      PL011State *s = (PL011State *)opaque;
> -    int r;
> +    int r = 0;
>
> -    r = s->read_count < pl011_get_fifo_depth(s);
> +    if ((s->cr & CR_UARTEN) && (s->cr & CR_RXE)) {
> +        r = s->read_count < pl011_get_fifo_depth(s);
> +    }
>      trace_pl011_can_receive(s->lcr, s->read_count, r);
>      return r;

I have a vague recollection of a previous conversation
where we discussed whether tightening up the UART-enable
checks would break existing only-tested-on-QEMU baremetal
simple example code. But I can't find it in my email
archive -- do you remember a discussion about this or
am I misremembering?

thanks
-- PMM