On Thu, 3 Oct 2024 at 08:10, Rasmus Villemoes ravi@prevas.dk wrote:
Before the previous patch, pasting a string of length x > CONFIG_SERIAL_RX_BUFFER_SIZE results in getting the last (x%CONFIG_SERIAL_RX_BUFFER_SIZE) characters from that string.
With the previous patch, one instead gets the last CONFIG_SERIAL_RX_BUFFER_SIZE characters repeatedly until the ->rd_ptr catches up.
Both behaviours are counter-intuitive, and happen because the code that checks for a character available from the hardware does not account for whether there is actually room in the software buffer to receive it. Fix that by adding such accounting. This also brings the software buffering more in line with how most hardware FIFOs behave (first received characters are kept, overflowing characters are dropped).
Signed-off-by: Rasmus Villemoes ravi@prevas.dk
drivers/serial/serial-uclass.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
Reviewed-by: Simon Glass sjg@chromium.org
diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c index 05fe9645bee..28d7a202afc 100644 --- a/drivers/serial/serial-uclass.c +++ b/drivers/serial/serial-uclass.c @@ -328,10 +328,11 @@ static int __serial_tstc(struct udevice *dev) static int _serial_tstc(struct udevice *dev) { struct serial_dev_priv *upriv = dev_get_uclass_priv(dev);
uint wr;
uint wr, avail;
/* Read all available chars into the RX buffer */while (__serial_tstc(dev)) {
/* Read all available chars into the RX buffer while there's room */avail = CONFIG_SERIAL_RX_BUFFER_SIZE - (upriv->wr_ptr - upriv->rd_ptr);while (avail-- && __serial_tstc(dev)) { wr = upriv->wr_ptr++ % CONFIG_SERIAL_RX_BUFFER_SIZE; upriv->buf[wr] = __serial_getc(dev); }-- 2.46.2