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stm32: spi: Fix race condition with the enabled boolean

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Sometimes the chipset task is slow enough that we might get messages from
the AP before chipset_in_state(CHIPSET_STATE_ON) is true. This causes us
to leave the spi off after our usual reset after every transaction
(see chrome-os-partner:31390). This would put an end to any EC communications.

Instead of relying on CHIPSET_STATE_ON we could just save the value of
"enabled" before we turn it off, then use that as a condition instead.

There shouldn't be a race condition on "enabled" because the only other place
it gets modified is in the hooks, which can't preempt spi_init
(which usually happens in the host command task).

The only problem is that in case of a sysjump enabled will be 0,
so CHIPSET_STATE_ON was left as a backup to handle that case.
This fixup was squashed from Ied3788f83fef548dff3b01bec93d0e40101ba0f7

TEST=Resume minnie from "echo mem>/sys/power/state" a few times, note ec still works
BUG=chrome-os-partner:39564, chrome-os-partner:39576
BRANCH=veyron

Change-Id: I7c33243faebfd74dc33451024c1d75080babee03
Signed-off-by: Alexandru M Stan <amstan@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/267593
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
This commit is contained in:
Alexandru M Stan
2015-04-27 16:50:04 -07:00
committed by ChromeOS Commit Bot
parent f19a1086bc
commit 0fc9f26364
1 changed files with 6 additions and 2 deletions
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8
chip/stm32/spi.c
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@@ -617,6 +617,7 @@ DECLARE_HOOK(HOOK_CHIPSET_SUSPEND, spi_chipset_shutdown, HOOK_PRIO_DEFAULT);
static void spi_init(void)
{
stm32_spi_regs_t *spi = STM32_SPI1_REGS;
uint8_t was_enabled = enabled;
/* Reset the SPI Peripheral to clear any existing weird states. */
/* Fix for bug chrome-os-partner:31390 */
@@ -646,8 +647,11 @@ static void spi_init(void)
gpio_enable_interrupt(GPIO_SPI1_NSS);
/* If chipset is already on, prepare for transactions */
if (chipset_in_state(CHIPSET_STATE_ON))
/*
* If we were already enabled or chipset is already on,
* prepare for transaction
*/
if (was_enabled || chipset_in_state(CHIPSET_STATE_ON))
spi_chipset_startup();
}
DECLARE_HOOK(HOOK_INIT, spi_init, HOOK_PRIO_DEFAULT);