| Message ID | 20250108-drm-dp-msm-add-lttpr-transparent-mode-set-v4-1-918949bc2e3a@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v4,1/4] drm/dp: Add helper to set LTTPRs in transparent mode | expand |
On 25-01-08 16:17:47, Bjorn Andersson wrote: > On Wed, Jan 08, 2025 at 04:31:43PM +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. > > > > Also add a generic wrapper for the helper that handles the explicit > > disabling of non-transparent mode and its disable->enable sequence > > mentioned in the DP Standard v2.0 section 3.6.6.1. Do this in order > > to move this handling out of the vendor specific driver implementation > > into the generic framework. > > > > Tested-by: Johan Hovold <johan+linaro@kernel.org> > > Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> > > Reviewed-by: Johan Hovold <johan+linaro@kernel.org> > > Signed-off-by: Abel Vesa <abel.vesa@linaro.org> > > --- > > drivers/gpu/drm/display/drm_dp_helper.c | 62 +++++++++++++++++++++++++++++++++ > > include/drm/display/drm_dp_helper.h | 2 ++ > > 2 files changed, 64 insertions(+) > > > > diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c > > index da3c8521a7fa7d3c9761377363cdd4b44ab1106e..fa7eff94d408718a1762834597f0cd51376d2596 100644 > > --- a/drivers/gpu/drm/display/drm_dp_helper.c > > +++ b/drivers/gpu/drm/display/drm_dp_helper.c > > @@ -2817,6 +2817,68 @@ 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 > > kernel-doc functions should have () suffix Yes, will add. > > > + * @aux: DisplayPort AUX channel > > + * @enable: Enable or disable transparent mode > > + * > > + * Returns 0 on success or a negative error code on failure. > > And this should be "Return: ...". Will fix as well. > > > + */ > > +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; > > + int ret = drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_MODE, val); > > + > > + if (ret < 0) > > + return ret; > > + > > + return (ret == 1) ? 0 : -EIO; > > +} > > +EXPORT_SYMBOL(drm_dp_lttpr_set_transparent_mode); > > + > > +/** > > + * drm_dp_lttpr_init - init LTTPR transparency mode according to DP standard > > + * > > Documentation also explicitly says not to leave a blank line here... Will drop the blank line. > > Regards, > Bjorn > Thanks for reviewing! Abel
diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c index da3c8521a7fa7d3c9761377363cdd4b44ab1106e..fa7eff94d408718a1762834597f0cd51376d2596 100644 --- a/drivers/gpu/drm/display/drm_dp_helper.c +++ b/drivers/gpu/drm/display/drm_dp_helper.c @@ -2817,6 +2817,68 @@ 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; + int ret = drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_MODE, val); + + if (ret < 0) + return ret; + + return (ret == 1) ? 0 : -EIO; +} +EXPORT_SYMBOL(drm_dp_lttpr_set_transparent_mode); + +/** + * drm_dp_lttpr_init - init LTTPR transparency mode according to DP standard + * + * @aux: DisplayPort AUX channel + * @lttpr_count: Number of LTTPRs. Between 0 and 8, according to DP standard. + * Negative error code for any non-valid number. + * See drm_dp_lttpr_count(). + * + * Returns 0 on success or a negative error code on failure. + */ +int drm_dp_lttpr_init(struct drm_dp_aux *aux, int lttpr_count) +{ + int ret; + + if (!lttpr_count) + return 0; + + /* + * See DP Standard v2.0 3.6.6.1 about the explicit disabling of + * non-transparent mode and the disable->enable non-transparent mode + * sequence. + */ + ret = drm_dp_lttpr_set_transparent_mode(aux, true); + if (ret) + return ret; + + if (lttpr_count < 0) + return -ENODEV; + + if (drm_dp_lttpr_set_transparent_mode(aux, false)) { + /* + * Roll-back to transparent mode if setting non-transparent + * mode has failed + */ + drm_dp_lttpr_set_transparent_mode(aux, true); + return -EINVAL; + } + + return 0; +} +EXPORT_SYMBOL(drm_dp_lttpr_init); + /** * 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 8f4054a560396a43750570a8c2e95624039ab8ad..3311df3b58255cf0620391d0948ccf6b569a8a34 100644 --- a/include/drm/display/drm_dp_helper.h +++ b/include/drm/display/drm_dp_helper.h @@ -630,6 +630,8 @@ 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_init(struct drm_dp_aux *aux, int lttpr_count); 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]);