[PATCH 5.16 0823/1017] media: atomisp_gmin_platform: Add DMI quirk to not turn AXP ELDO2 regulator off on some boards

Greg Kroah-Hartman
2022-04-05T10:09:11Z

From: Hans de Goede <hdegoede@redhat.com>

[ Upstream commit 2c39a01154ea57d596470afa1d278e3be3b37f6a ]

The TrekStor SurfTab duo W1 10.1 has a hw bug where turning eldo2 back on
after having turned it off causes the CPLM3218 ambient-light-sensor on
the front camera sensor's I2C bus to crash, hanging the bus.

Add a DMI quirk table for systems on which to leave eldo2 on.

Note an alternative fix is to turn off the CPLM3218 ambient-light-sensor
as long as the camera sensor is being used, this is what Windows seems
to do as a workaround (based on analyzing the DSDT). But that is not
easy to do cleanly under Linux.

Link: https://lore.kernel.org/linux-media/20220116215204.307649-10-hdegoede@redhat.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../media/atomisp/pci/atomisp_gmin_platform.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

diff --git a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
index 62dc06e22476..cd0a771454da 100644
--- a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
+++ b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
@@ -729,6 +729,21 @@ static int axp_regulator_set(struct device *dev, struct gmin_subdev *gs,
return 0;
}

+/*
+ * Some boards contain a hw-bug where turning eldo2 back on after having turned
+ * it off causes the CPLM3218 ambient-light-sensor on the image-sensor's I2C bus
+ * to crash, hanging the bus. Do not turn eldo2 off on these systems.
+ */
+static const struct dmi_system_id axp_leave_eldo2_on_ids[] = {
+ {
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "TrekStor"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "SurfTab duo W1 10.1 (VT4)"),
+ },
+ },
+ { }
+};
+
static int axp_v1p8_on(struct device *dev, struct gmin_subdev *gs)
{
int ret;
@@ -763,6 +778,9 @@ static int axp_v1p8_off(struct device *dev, struct gmin_subdev *gs)
if (ret)
return ret;

+ if (dmi_check_system(axp_leave_eldo2_on_ids))
+ return 0;
+
ret = axp_regulator_set(dev, gs, gs->eldo2_sel_reg, gs->eldo2_1p8v,
ELDO_CTRL_REG, gs->eldo2_ctrl_shift, false);
return ret;
--
2.34.1