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Re: [PATCH v6 7/7] hw/char/pl011: Implement TX FIFO


From: Peter Maydell
Subject: Re: [PATCH v6 7/7] hw/char/pl011: Implement TX FIFO
Date: Mon, 17 Feb 2025 14:37:13 +0000

On Sat, 8 Feb 2025 at 16:39, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>
> If the UART back-end chardev doesn't drain data as fast as stdout
> does or blocks, buffer in the TX FIFO to try again later.
>
> This avoids having the IO-thread busy waiting on chardev back-ends,
> reported recently when testing the Trusted Reference Stack and
> using the socket backend.
>
> Implement registering a front-end 'watch' callback on back-end
> events, so we can resume transmitting when the back-end is writable
> again, not blocking the main loop.
>
> Similarly to the RX FIFO path, FIFO level selection is not
> implemented (interrupt is triggered when a single byte is available
> in the FIFO).
>
> Reported-by: Mikko Rapeli <mikko.rapeli@linaro.org>
> Suggested-by: Alex Bennée <alex.bennee@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM



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