From 13557fd392890cbd985bceba7f717e01efd674b8 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 27 Jul 2020 16:45:50 +0100 Subject: [PATCH] hw/timer/imx_epit: Avoid assertion when CR.SWR is written MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The imx_epit device has a software-controllable reset triggered by setting the SWR bit in the CR register. An error in commit cc2722ec83ad9 means that we will end up assert()ing if the guest does this, because the code in imx_epit_write() starts ptimer transactions, and then imx_epit_reset() also starts ptimer transactions, triggering "ptimer_transaction_begin: Assertion `!s->in_transaction' failed". The cleanest way to avoid this double-transaction is to move the start-transaction for the CR write handling down below the check of the SWR bit. Fixes: https://bugs.launchpad.net/qemu/+bug/1880424 Fixes: cc2722ec83ad944505fe Signed-off-by: Peter Maydell Reviewed-by: Philippe Mathieu-Daudé Message-id: 20200727154550.3409-1-peter.maydell@linaro.org --- hw/timer/imx_epit.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/hw/timer/imx_epit.c b/hw/timer/imx_epit.c index baf6338e1a..ebd58254d1 100644 --- a/hw/timer/imx_epit.c +++ b/hw/timer/imx_epit.c @@ -199,15 +199,22 @@ static void imx_epit_write(void *opaque, hwaddr offset, uint64_t value, switch (offset >> 2) { case 0: /* CR */ - ptimer_transaction_begin(s->timer_cmp); - ptimer_transaction_begin(s->timer_reload); oldcr = s->cr; s->cr = value & 0x03ffffff; if (s->cr & CR_SWR) { /* handle the reset */ imx_epit_reset(DEVICE(s)); - } else { + /* + * TODO: could we 'break' here? following operations appear + * to duplicate the work imx_epit_reset() already did. + */ + } + + ptimer_transaction_begin(s->timer_cmp); + ptimer_transaction_begin(s->timer_reload); + + if (!(s->cr & CR_SWR)) { imx_epit_set_freq(s); }