Reading DPCD registers has side-effects in general. In particular
accessing registers outside of the link training register range
(0x102-0x106, 0x202-0x207, 0x200c-0x200f, 0x2216) is explicitly
forbidden by the DP v2.1 Standard, see
3.6.5.1 DPTX AUX Transaction Handling Mandates
3.6.7.4 128b/132b DP Link Layer LTTPR Link Training Mandates
Based on my tests, accessing the DPCD_REV register during the link
training of an UHBR TBT DP tunnel sink leads to link training failures.
Solve the above by using the DP_LANE0_1_STATUS (0x202) register for the
DPCD register access quirk.
Cc: <stable(a)vger.kernel.org>
Cc: Ville Syrjälä <ville.syrjala(a)linux.intel.com>
Cc: Jani Nikula <jani.nikula(a)linux.intel.com>
Acked-by: Jani Nikula <jani.nikula(a)linux.intel.com>
Signed-off-by: Imre Deak <imre.deak(a)intel.com>
---
drivers/gpu/drm/display/drm_dp_helper.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index f2a6559a27100..dc622c78db9d4 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -725,7 +725,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
* monitor doesn't power down exactly after the throw away read.
*/
if (!aux->is_remote) {
- ret = drm_dp_dpcd_probe(aux, DP_DPCD_REV);
+ ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS);
if (ret < 0)
return ret;
}
--
2.44.2
Previously during probe, 1 is unconditionally taken as current
brightness value and set to props.brightness, which will be considered
as the brightness before suspend and restored to EC on resume. Since a
brightness value of 1 almost never matches EC's state on coldboot (my
laptop's EC defaults to 80), this causes surprising changes of screen
brightness on the first time of resume after coldboot.
Let's get brightness from EC and take it as the current brightness on
probe of the laptop driver to avoid the surprising behavior. Tested on
TongFang L860-T2 3A5000 laptop.
Cc: stable(a)vger.kernel.org
Fixes: 6246ed09111f ("LoongArch: Add ACPI-based generic laptop driver")
Signed-off-by: Yao Zi <ziyao(a)disroot.org>
---
drivers/platform/loongarch/loongson-laptop.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/platform/loongarch/loongson-laptop.c b/drivers/platform/loongarch/loongson-laptop.c
index 99203584949d..828bd62e3596 100644
--- a/drivers/platform/loongarch/loongson-laptop.c
+++ b/drivers/platform/loongarch/loongson-laptop.c
@@ -392,7 +392,7 @@ static int laptop_backlight_register(void)
if (!acpi_evalf(hotkey_handle, &status, "ECLL", "d"))
return -EIO;
- props.brightness = 1;
+ props.brightness = ec_get_brightness();
props.max_brightness = status;
props.type = BACKLIGHT_PLATFORM;
--
2.49.0