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[v2,1/9] hw/char/pl011: Warn when using disabled receiver

Message ID 20250220092903.3726-2-philmd@linaro.org
State New
Headers show
Series hw/char: Improve RX FIFO depth uses | expand

Commit Message

Philippe Mathieu-Daudé Feb. 20, 2025, 9:28 a.m. UTC 
We shouldn't receive characters when the full UART or its
receiver is disabled. However we don't want to break the
possibly incomplete "my first bare metal assembly program"s,
so we choose to simply display a warning when this occurs.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/char/pl011.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Comments

Luc Michel Feb. 20, 2025, 9:52 a.m. UTC | #1 
On 10:28 Thu 20 Feb     , Philippe Mathieu-Daudé wrote:
> We shouldn't receive characters when the full UART or its
> receiver is disabled. However we don't want to break the
> possibly incomplete "my first bare metal assembly program"s,
> so we choose to simply display a warning when this occurs.
> 
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Reviewed-by: Luc Michel <luc.michel@amd.com>

> ---
>  hw/char/pl011.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/hw/char/pl011.c b/hw/char/pl011.c
> index 06ce851044d..12a2d4bc7bd 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)
> @@ -487,6 +488,14 @@ static int pl011_can_receive(void *opaque)
>      PL011State *s = (PL011State *)opaque;
>      int r;
> 
> +    if (!(s->cr & CR_UARTEN)) {
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "PL011 receiving data on disabled UART\n");
> +    }
> +    if (!(s->cr & CR_RXE)) {
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "PL011 receiving data on disabled RX UART\n");
> +    }
>      r = s->read_count < pl011_get_fifo_depth(s);
>      trace_pl011_can_receive(s->lcr, s->read_count, r);
>      return r;
> --
> 2.47.1
> 

--
diff mbox series

Patch

diff --git a/hw/char/pl011.c b/hw/char/pl011.c
index 06ce851044d..12a2d4bc7bd 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)
@@ -487,6 +488,14 @@  static int pl011_can_receive(void *opaque)
     PL011State *s = (PL011State *)opaque;
     int r;
 
+    if (!(s->cr & CR_UARTEN)) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "PL011 receiving data on disabled UART\n");
+    }
+    if (!(s->cr & CR_RXE)) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "PL011 receiving data on disabled RX UART\n");
+    }
     r = s->read_count < pl011_get_fifo_depth(s);
     trace_pl011_can_receive(s->lcr, s->read_count, r);
     return r;