Abel Vesa
2024-Oct-31 15:12 UTC
[PATCH RFC 1/4] drm/dp: Add helper to set LTTPRs in transparent mode
According to the DisplayPort standard, LTTPRs have two operating
modes:
- non-transparent - it replies to DPCD LTTPR field specific AUX
requests, while passes through all other AUX requests
- transparent - it passes through all AUX requests.
Switching between this two modes is done by the DPTX by issuing
an AUX write to the DPCD PHY_REPEATER_MODE register.
Add a generic helper that allows switching between these modes.
Signed-off-by: Abel Vesa <abel.vesa at linaro.org>
---
drivers/gpu/drm/display/drm_dp_helper.c | 17 +++++++++++++++++
include/drm/display/drm_dp_helper.h | 1 +
2 files changed, 18 insertions(+)
diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index
6ee51003de3ce616c3a52653c2f1979ad7658e21..38d612345986ad54b42228902ea718a089d169c4
100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -2694,6 +2694,23 @@ int drm_dp_lttpr_max_link_rate(const u8
caps[DP_LTTPR_COMMON_CAP_SIZE])
}
EXPORT_SYMBOL(drm_dp_lttpr_max_link_rate);
+/**
+ * drm_dp_lttpr_set_transparent_mode - set the LTTPR in transparent mode
+ * @aux: DisplayPort AUX channel
+ * @enable: Enable or disable transparent mode
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+
+int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux, bool enable)
+{
+ u8 val = enable ? DP_PHY_REPEATER_MODE_TRANSPARENT :
+ DP_PHY_REPEATER_MODE_NON_TRANSPARENT;
+
+ return drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_MODE, val);
+}
+EXPORT_SYMBOL(drm_dp_lttpr_set_transparent_mode);
+
/**
* drm_dp_lttpr_max_lane_count - get the maximum lane count supported by all
LTTPRs
* @caps: LTTPR common capabilities
diff --git a/include/drm/display/drm_dp_helper.h
b/include/drm/display/drm_dp_helper.h
index
279624833ea9259809428162f4e845654359f8c9..8821ab2d36b0e04d38ccbdddcb703b34de7ed680
100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -625,6 +625,7 @@ int drm_dp_read_lttpr_phy_caps(struct drm_dp_aux *aux,
u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
int drm_dp_lttpr_count(const u8 cap[DP_LTTPR_COMMON_CAP_SIZE]);
int drm_dp_lttpr_max_link_rate(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE]);
+int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux, bool enable);
int drm_dp_lttpr_max_lane_count(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE]);
bool drm_dp_lttpr_voltage_swing_level_3_supported(const u8
caps[DP_LTTPR_PHY_CAP_SIZE]);
bool drm_dp_lttpr_pre_emphasis_level_3_supported(const u8
caps[DP_LTTPR_PHY_CAP_SIZE]);
--
2.34.1
Imre Deak
2024-Oct-31 21:05 UTC
[PATCH RFC 1/4] drm/dp: Add helper to set LTTPRs in transparent mode
On Thu, Oct 31, 2024 at 05:12:45PM +0200, Abel Vesa wrote:> According to the DisplayPort standard, LTTPRs have two operating > modes: > - non-transparent - it replies to DPCD LTTPR field specific AUX > requests, while passes through all other AUX requests > - transparent - it passes through all AUX requests. > > Switching between this two modes is done by the DPTX by issuing > an AUX write to the DPCD PHY_REPEATER_MODE register. > > Add a generic helper that allows switching between these modes. > > Signed-off-by: Abel Vesa <abel.vesa at linaro.org> > --- > drivers/gpu/drm/display/drm_dp_helper.c | 17 +++++++++++++++++ > include/drm/display/drm_dp_helper.h | 1 + > 2 files changed, 18 insertions(+) > > diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c > index 6ee51003de3ce616c3a52653c2f1979ad7658e21..38d612345986ad54b42228902ea718a089d169c4 100644 > --- a/drivers/gpu/drm/display/drm_dp_helper.c > +++ b/drivers/gpu/drm/display/drm_dp_helper.c > @@ -2694,6 +2694,23 @@ int drm_dp_lttpr_max_link_rate(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE]) > } > EXPORT_SYMBOL(drm_dp_lttpr_max_link_rate); > > +/** > + * drm_dp_lttpr_set_transparent_mode - set the LTTPR in transparent mode > + * @aux: DisplayPort AUX channel > + * @enable: Enable or disable transparent mode > + * > + * Returns 0 on success or a negative error code on failure.Should be "Returns 1 on success".> + */ > + > +int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux, bool enable) > +{ > + u8 val = enable ? DP_PHY_REPEATER_MODE_TRANSPARENT : > + DP_PHY_REPEATER_MODE_NON_TRANSPARENT; > + > + return drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_MODE, val); > +} > +EXPORT_SYMBOL(drm_dp_lttpr_set_transparent_mode); > + > /** > * drm_dp_lttpr_max_lane_count - get the maximum lane count supported by all LTTPRs > * @caps: LTTPR common capabilities > diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h > index 279624833ea9259809428162f4e845654359f8c9..8821ab2d36b0e04d38ccbdddcb703b34de7ed680 100644 > --- a/include/drm/display/drm_dp_helper.h > +++ b/include/drm/display/drm_dp_helper.h > @@ -625,6 +625,7 @@ int drm_dp_read_lttpr_phy_caps(struct drm_dp_aux *aux, > u8 caps[DP_LTTPR_PHY_CAP_SIZE]); > int drm_dp_lttpr_count(const u8 cap[DP_LTTPR_COMMON_CAP_SIZE]); > int drm_dp_lttpr_max_link_rate(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE]); > +int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux, bool enable); > int drm_dp_lttpr_max_lane_count(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE]); > bool drm_dp_lttpr_voltage_swing_level_3_supported(const u8 caps[DP_LTTPR_PHY_CAP_SIZE]); > bool drm_dp_lttpr_pre_emphasis_level_3_supported(const u8 caps[DP_LTTPR_PHY_CAP_SIZE]); > > -- > 2.34.1 >