Peter Maydell <peter.mayd...@linaro.org> writes:
> On Mon, 22 May 2023 at 16:32, Philippe Mathieu-Daudé <phi...@linaro.org> > wrote: >> >> Do not transmit characters when UART or transmitter are disabled. >> >> Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org> > > Last time somebody tried to add checks on the tx/rx enable bits > for the PL011 it broke 'make check' because the hand-rolled > UART code in boot-serial-test and migration-test doesn't > set up the UART control register strictly correctly: > > https://lore.kernel.org/qemu-devel/cafeaca8zdmjp7g0evpxcb1jisgarzabqpv0xr5wqur213mb...@mail.gmail.com/ > > Given that imposing these checks doesn't help anything > much and might break naive bare-metal tested-only-on-QEMU > code, is it worthwhile ? Surely we aim to be a correct model so the fix should be in our naive and incorrect code? > >> static void pl011_write_tx(PL011State *s, const uint8_t *buf, int length) >> { >> - /* ??? Check if transmitter is enabled. */ >> + if (!(s->cr & (CR_UARTEN | CR_TXE))) { > > This will allow TX if either UARTEN or TXE is set, which > probably isn't what you meant. > >> + return; >> + } >> >> /* XXX this blocks entire thread. Rewrite to use >> * qemu_chr_fe_write and background I/O callbacks */ > > thanks > -- PMM -- Alex Bennée Virtualisation Tech Lead @ Linaro
