Re: [Qemu-devel] [PATCH v2 1/4] hw/char: Implement nRF51 SoC UART

[Julia Suvorova]

On 10.08.2018 09:02, Stefan Hajnoczi wrote:
> On Wed, Aug 8, 2018 at 10:07 PM, Julia Suvorova <address@hidden> wrote:
> > +static uint64_t uart_read(void *opaque, hwaddr addr, unsigned int size)
> > +{
> > +    NRF51UARTState *s = NRF51_UART(opaque);
> > +    uint64_t r;
> > +
> > +    if (!s->enabled) {
> > +        return 0;
> > +    }
> > +
> > +    switch (addr) {
> > +    case A_UART_RXD:
> > +        r = s->rx_fifo[s->rx_fifo_pos];
> > +        if (s->rx_started && s->rx_fifo_len) {
> > +            qemu_chr_fe_accept_input(&s->chr);
>
> Should this be called after popping a byte from the rx fifo?  That way
> .can_receive() will return true again.

Could you explain more, please?

> > +static void nrf51_uart_realize(DeviceState *dev, Error **errp)
> > +{
> > +    NRF51UARTState *s = NRF51_UART(dev);
> > +
> > +    qemu_chr_fe_set_handlers(&s->chr, uart_can_receive, uart_receive,
> > +                             uart_event, NULL, s, NULL, true);
> > +}
>
> unrealize() should set the handlers to NULL.  That way the device can
> be removed without leaving callbacks registered.

I don't know the reason, but almost all char devices do not implement
this function. Maybe, because when you quit qemu, qemu_chr_cleanup() is called.

Best regards, Julia Suvorova.