[PATCH] ACPI / LPSS: Save/restore LPSS private registers also on Lynxpoint

Jarkko Nikula
2019-08-22T08:32:06Z

My assumption in the commit b53548f9d9e4 ("spi: pxa2xx: Remove LPSS private
register restoring during resume") that Intel Lynxpoint and compatible
based chipsets may not need LPSS private registers saving and restoring
over suspend/resume cycle turned out to be false on Intel Broadwell.

Curtis Malainey sent a patch bringing above change back and reported the
LPSS SPI Chip Select control was lost over suspend/resume cycle on
Broadwell machine.

Instead of reverting above commit lets add LPSS private register
saving/restoring also for all LPSS SPI, I2C and UART controllers on
Lynxpoint and compatible chipset to make sure context is not lost in
case nothing else preserves it like firmware or if LPSS is always on.

Fixes: b53548f9d9e4 ("spi: pxa2xx: Remove LPSS private register restoring during resume")
Reported-by: Curtis Malainey <cujomalainey@chromium.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
drivers/acpi/acpi_lpss.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
index d696f165a50e..60bbc5090abe 100644
--- a/drivers/acpi/acpi_lpss.c
+++ b/drivers/acpi/acpi_lpss.c
@@ -219,12 +219,13 @@ static void bsw_pwm_setup(struct lpss_private_data *pdata)
}

static const struct lpss_device_desc lpt_dev_desc = {
- .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_LTR,
+ .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_LTR
+ | LPSS_SAVE_CTX,
.prv_offset = 0x800,
};

static const struct lpss_device_desc lpt_i2c_dev_desc = {
- .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_LTR,
+ .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_LTR | LPSS_SAVE_CTX,
.prv_offset = 0x800,
};

@@ -236,7 +237,8 @@ static struct property_entry uart_properties[] = {
};

static const struct lpss_device_desc lpt_uart_dev_desc = {
- .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_LTR,
+ .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_LTR
+ | LPSS_SAVE_CTX,
.clk_con_id = "baudclk",
.prv_offset = 0x800,
.setup = lpss_uart_setup,
--
2.23.0.rc1