| Message ID | 1649938766-6768-4-git-send-email-quic_sbillaka@quicinc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add support for the eDP panel over aux_bus | expand |
Hi, On Thu, Apr 14, 2022 at 5:20 AM Sankeerth Billakanti <quic_sbillaka@quicinc.com> wrote: > > The source device should ensure the sink is ready before proceeding to > read the sink capability or perform any aux transactions. The sink > will indicate its readiness by asserting the HPD line. The controller > driver needs to wait for the hpd line to be asserted by the sink before > it performs any aux transactions. > > The eDP sink is assumed to be always connected. It needs power from the > source and its HPD line will be asserted only after the panel is powered > on. The panel power will be enabled from the panel-edp driver and only > after that, the hpd line will be asserted. > > Whereas for DP, the sink can be hotplugged and unplugged anytime. The hpd > line gets asserted to indicate the sink is connected and ready. Hence > there is no need to wait for the hpd line to be asserted for a DP sink. > > Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com> > --- It might be worth mentioning "after the cut" that we may eventually end up changing the rules if people like my proposal [1]. However, what your code is doing here for eDP is correct as things are currently intended to work and it would make sense to land it while we debate about whether we want to add the is_hpd_asserted() callback like my patch does. [1] https://lore.kernel.org/r/20220408193536.RFC.3.Icf57bb12233a47727013c6ab69eebf803e22ebc1@changeid/ > Changes in v7: > - add a comment to say why the wait si done for eDP > - correct the commit text > > Changes in v6: > - Wait for hpd high only for eDP > - Split into smaller patches > > drivers/gpu/drm/msm/dp/dp_aux.c | 21 ++++++++++++++++++++- > drivers/gpu/drm/msm/dp/dp_aux.h | 3 ++- > drivers/gpu/drm/msm/dp/dp_catalog.c | 13 +++++++++++++ > drivers/gpu/drm/msm/dp/dp_catalog.h | 1 + > drivers/gpu/drm/msm/dp/dp_display.c | 2 +- > 5 files changed, 37 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c b/drivers/gpu/drm/msm/dp/dp_aux.c > index 6d36f63..cf0739f 100644 > --- a/drivers/gpu/drm/msm/dp/dp_aux.c > +++ b/drivers/gpu/drm/msm/dp/dp_aux.c > @@ -36,6 +36,7 @@ struct dp_aux_private { > bool initted; > u32 offset; > u32 segment; > + bool is_edp; Kinda nitty, but can you put it next to the other booleans? This will help with structure packing. > struct drm_dp_aux dp_aux; > }; > @@ -337,6 +338,22 @@ static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux, > goto exit; > } > > + /* > + * For eDP it's important to give a reasonably long wait here for HPD > + * to be asserted. This is because the panel driver may have _just_ > + * turned on the panel and then tried to do an AUX transfer. The panel > + * driver has no way of knowing when the panel is ready, so it's up > + * to us to wait. For DP we never get into this situation so let's > + * avoid ever doing the extra long wait for DP. > + */ > + if (aux->is_edp) { > + ret = dp_catalog_aux_wait_for_hpd_connect_state(aux->catalog); > + if (ret) { > + DRM_DEBUG_DP("Panel not ready for aux transactions\n"); > + goto exit; > + } > + } > + > dp_aux_update_offset_and_segment(aux, msg); > dp_aux_transfer_helper(aux, msg, true); > > @@ -491,7 +508,8 @@ void dp_aux_unregister(struct drm_dp_aux *dp_aux) > drm_dp_aux_unregister(dp_aux); > } > > -struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog) > +struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog, > + bool is_edp) nit: I think indentation rules for this file are that the type of the argument for the 2nd line should line up right under the 1st. Thus you should delete one tab character and insert 6 spaces before the "bool". Similar in other places, like your header file. Stuff above is all nits and this looks right to me. I'm happy with: Reviewed-by: Douglas Anderson <dianders@chromium.org>
diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c b/drivers/gpu/drm/msm/dp/dp_aux.c index 6d36f63..cf0739f 100644 --- a/drivers/gpu/drm/msm/dp/dp_aux.c +++ b/drivers/gpu/drm/msm/dp/dp_aux.c @@ -36,6 +36,7 @@ struct dp_aux_private { bool initted; u32 offset; u32 segment; + bool is_edp; struct drm_dp_aux dp_aux; }; @@ -337,6 +338,22 @@ static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux, goto exit; } + /* + * For eDP it's important to give a reasonably long wait here for HPD + * to be asserted. This is because the panel driver may have _just_ + * turned on the panel and then tried to do an AUX transfer. The panel + * driver has no way of knowing when the panel is ready, so it's up + * to us to wait. For DP we never get into this situation so let's + * avoid ever doing the extra long wait for DP. + */ + if (aux->is_edp) { + ret = dp_catalog_aux_wait_for_hpd_connect_state(aux->catalog); + if (ret) { + DRM_DEBUG_DP("Panel not ready for aux transactions\n"); + goto exit; + } + } + dp_aux_update_offset_and_segment(aux, msg); dp_aux_transfer_helper(aux, msg, true); @@ -491,7 +508,8 @@ void dp_aux_unregister(struct drm_dp_aux *dp_aux) drm_dp_aux_unregister(dp_aux); } -struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog) +struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog, + bool is_edp) { struct dp_aux_private *aux; @@ -506,6 +524,7 @@ struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog) init_completion(&aux->comp); aux->cmd_busy = false; + aux->is_edp = is_edp; mutex_init(&aux->mutex); aux->dev = dev; diff --git a/drivers/gpu/drm/msm/dp/dp_aux.h b/drivers/gpu/drm/msm/dp/dp_aux.h index 82afc8d..c99aeec 100644 --- a/drivers/gpu/drm/msm/dp/dp_aux.h +++ b/drivers/gpu/drm/msm/dp/dp_aux.h @@ -16,7 +16,8 @@ void dp_aux_init(struct drm_dp_aux *dp_aux); void dp_aux_deinit(struct drm_dp_aux *dp_aux); void dp_aux_reconfig(struct drm_dp_aux *dp_aux); -struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog); +struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog, + bool is_edp); void dp_aux_put(struct drm_dp_aux *aux); #endif /*__DP_AUX_H_*/ diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.c b/drivers/gpu/drm/msm/dp/dp_catalog.c index 07f2389..4282a98 100644 --- a/drivers/gpu/drm/msm/dp/dp_catalog.c +++ b/drivers/gpu/drm/msm/dp/dp_catalog.c @@ -242,6 +242,19 @@ void dp_catalog_aux_update_cfg(struct dp_catalog *dp_catalog) phy_calibrate(phy); } +int dp_catalog_aux_wait_for_hpd_connect_state(struct dp_catalog *dp_catalog) +{ + u32 state; + struct dp_catalog_private *catalog = container_of(dp_catalog, + struct dp_catalog_private, dp_catalog); + + /* poll for hpd connected status every 2ms and timeout after 500ms */ + return readl_poll_timeout(catalog->io->dp_controller.aux.base + + REG_DP_DP_HPD_INT_STATUS, + state, state & DP_DP_HPD_STATE_STATUS_CONNECTED, + 2000, 500000); +} + static void dump_regs(void __iomem *base, int len) { int i; diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.h b/drivers/gpu/drm/msm/dp/dp_catalog.h index 7dea101..45140a3 100644 --- a/drivers/gpu/drm/msm/dp/dp_catalog.h +++ b/drivers/gpu/drm/msm/dp/dp_catalog.h @@ -84,6 +84,7 @@ int dp_catalog_aux_clear_hw_interrupts(struct dp_catalog *dp_catalog); void dp_catalog_aux_reset(struct dp_catalog *dp_catalog); void dp_catalog_aux_enable(struct dp_catalog *dp_catalog, bool enable); void dp_catalog_aux_update_cfg(struct dp_catalog *dp_catalog); +int dp_catalog_aux_wait_for_hpd_connect_state(struct dp_catalog *dp_catalog); u32 dp_catalog_aux_get_irq(struct dp_catalog *dp_catalog); /* DP Controller APIs */ diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c index 1339c45..c7277f0 100644 --- a/drivers/gpu/drm/msm/dp/dp_display.c +++ b/drivers/gpu/drm/msm/dp/dp_display.c @@ -805,7 +805,7 @@ static int dp_init_sub_modules(struct dp_display_private *dp) goto error; } - dp->aux = dp_aux_get(dev, dp->catalog); + dp->aux = dp_aux_get(dev, dp->catalog, dp->dp_display.is_edp); if (IS_ERR(dp->aux)) { rc = PTR_ERR(dp->aux); DRM_ERROR("failed to initialize aux, rc = %d\n", rc);
The source device should ensure the sink is ready before proceeding to read the sink capability or perform any aux transactions. The sink will indicate its readiness by asserting the HPD line. The controller driver needs to wait for the hpd line to be asserted by the sink before it performs any aux transactions. The eDP sink is assumed to be always connected. It needs power from the source and its HPD line will be asserted only after the panel is powered on. The panel power will be enabled from the panel-edp driver and only after that, the hpd line will be asserted. Whereas for DP, the sink can be hotplugged and unplugged anytime. The hpd line gets asserted to indicate the sink is connected and ready. Hence there is no need to wait for the hpd line to be asserted for a DP sink. Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com> --- Changes in v7: - add a comment to say why the wait si done for eDP - correct the commit text Changes in v6: - Wait for hpd high only for eDP - Split into smaller patches drivers/gpu/drm/msm/dp/dp_aux.c | 21 ++++++++++++++++++++- drivers/gpu/drm/msm/dp/dp_aux.h | 3 ++- drivers/gpu/drm/msm/dp/dp_catalog.c | 13 +++++++++++++ drivers/gpu/drm/msm/dp/dp_catalog.h | 1 + drivers/gpu/drm/msm/dp/dp_display.c | 2 +- 5 files changed, 37 insertions(+), 3 deletions(-)