| Message ID | 20240503151129.3901815-11-l.stach@pengutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | improve Analogix DP AUX channel handling | expand |
On Fri, May 3, 2024 at 5:13 PM Lucas Stach <l.stach@pengutronix.de> wrote: > > Setting the link bandwidth may change the PLL parameters, which will cause > the PLL to go out of lock, so make sure to apply the MACRO_RST, which > according to the comment is required to be pulsed after the PLL is locked. > > Signed-off-by: Lucas Stach <l.stach@pengutronix.de> > --- > .../gpu/drm/bridge/analogix/analogix_dp_core.c | 18 ++++++++++-------- > 1 file changed, 10 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c > index b4a47311cfe8..736b2ed745e1 100644 > --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c > +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c > @@ -243,6 +243,11 @@ static int analogix_dp_link_start(struct analogix_dp_device *dp) > > /* Set link rate and count as you want to establish*/ > analogix_dp_set_link_bandwidth(dp, dp->link_train.link_rate); > + /* > + * MACRO_RST must be applied after the PLL_LOCK to avoid > + * the DP inter pair skew issue for at least 10 us > + */ > + analogix_dp_reset_macro(dp); > analogix_dp_set_lane_count(dp, dp->link_train.lane_count); > > /* Setup RX configuration */ > @@ -565,12 +570,6 @@ static int analogix_dp_full_link_train(struct analogix_dp_device *dp, > int retval = 0; > bool training_finished = false; > > - /* > - * MACRO_RST must be applied after the PLL_LOCK to avoid > - * the DP inter pair skew issue for at least 10 us > - */ > - analogix_dp_reset_macro(dp); > - > /* Initialize by reading RX's DPCD */ > analogix_dp_get_max_rx_bandwidth(dp, &dp->link_train.link_rate); > analogix_dp_get_max_rx_lane_count(dp, &dp->link_train.lane_count); > @@ -637,9 +636,12 @@ static int analogix_dp_fast_link_train(struct analogix_dp_device *dp) > u8 link_align, link_status[2]; > enum pll_status status; > > - analogix_dp_reset_macro(dp); > - > analogix_dp_set_link_bandwidth(dp, dp->link_train.link_rate); > + /* > + * MACRO_RST must be applied after the PLL_LOCK to avoid > + * the DP inter pair skew issue for at least 10 us > + */ > + analogix_dp_reset_macro(dp); > analogix_dp_set_lane_count(dp, dp->link_train.lane_count); > analogix_dp_set_lane_link_training(dp); > > -- > 2.39.2 > This patch does not apply on drm-misc/drm-misc-next as far as I can tell.
On Tue, May 7, 2024 at 3:07 PM Robert Foss <rfoss@kernel.org> wrote: > > On Fri, May 3, 2024 at 5:13 PM Lucas Stach <l.stach@pengutronix.de> wrote: > > > > Setting the link bandwidth may change the PLL parameters, which will cause > > the PLL to go out of lock, so make sure to apply the MACRO_RST, which > > according to the comment is required to be pulsed after the PLL is locked. > > > > Signed-off-by: Lucas Stach <l.stach@pengutronix.de> > > --- > > .../gpu/drm/bridge/analogix/analogix_dp_core.c | 18 ++++++++++-------- > > 1 file changed, 10 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c > > index b4a47311cfe8..736b2ed745e1 100644 > > --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c > > +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c > > @@ -243,6 +243,11 @@ static int analogix_dp_link_start(struct analogix_dp_device *dp) > > > > /* Set link rate and count as you want to establish*/ > > analogix_dp_set_link_bandwidth(dp, dp->link_train.link_rate); > > + /* > > + * MACRO_RST must be applied after the PLL_LOCK to avoid > > + * the DP inter pair skew issue for at least 10 us > > + */ > > + analogix_dp_reset_macro(dp); > > analogix_dp_set_lane_count(dp, dp->link_train.lane_count); > > > > /* Setup RX configuration */ > > @@ -565,12 +570,6 @@ static int analogix_dp_full_link_train(struct analogix_dp_device *dp, > > int retval = 0; > > bool training_finished = false; > > > > - /* > > - * MACRO_RST must be applied after the PLL_LOCK to avoid > > - * the DP inter pair skew issue for at least 10 us > > - */ > > - analogix_dp_reset_macro(dp); > > - > > /* Initialize by reading RX's DPCD */ > > analogix_dp_get_max_rx_bandwidth(dp, &dp->link_train.link_rate); > > analogix_dp_get_max_rx_lane_count(dp, &dp->link_train.lane_count); > > @@ -637,9 +636,12 @@ static int analogix_dp_fast_link_train(struct analogix_dp_device *dp) > > u8 link_align, link_status[2]; > > enum pll_status status; > > > > - analogix_dp_reset_macro(dp); > > - > > analogix_dp_set_link_bandwidth(dp, dp->link_train.link_rate); > > + /* > > + * MACRO_RST must be applied after the PLL_LOCK to avoid > > + * the DP inter pair skew issue for at least 10 us > > + */ > > + analogix_dp_reset_macro(dp); > > analogix_dp_set_lane_count(dp, dp->link_train.lane_count); > > analogix_dp_set_lane_link_training(dp); > > > > -- > > 2.39.2 > > > > This patch does not apply on drm-misc/drm-misc-next as far as I can tell. Reviewed-by: Robert Foss <rfoss@kernel.org>
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c index b4a47311cfe8..736b2ed745e1 100644 --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c @@ -243,6 +243,11 @@ static int analogix_dp_link_start(struct analogix_dp_device *dp) /* Set link rate and count as you want to establish*/ analogix_dp_set_link_bandwidth(dp, dp->link_train.link_rate); + /* + * MACRO_RST must be applied after the PLL_LOCK to avoid + * the DP inter pair skew issue for at least 10 us + */ + analogix_dp_reset_macro(dp); analogix_dp_set_lane_count(dp, dp->link_train.lane_count); /* Setup RX configuration */ @@ -565,12 +570,6 @@ static int analogix_dp_full_link_train(struct analogix_dp_device *dp, int retval = 0; bool training_finished = false; - /* - * MACRO_RST must be applied after the PLL_LOCK to avoid - * the DP inter pair skew issue for at least 10 us - */ - analogix_dp_reset_macro(dp); - /* Initialize by reading RX's DPCD */ analogix_dp_get_max_rx_bandwidth(dp, &dp->link_train.link_rate); analogix_dp_get_max_rx_lane_count(dp, &dp->link_train.lane_count); @@ -637,9 +636,12 @@ static int analogix_dp_fast_link_train(struct analogix_dp_device *dp) u8 link_align, link_status[2]; enum pll_status status; - analogix_dp_reset_macro(dp); - analogix_dp_set_link_bandwidth(dp, dp->link_train.link_rate); + /* + * MACRO_RST must be applied after the PLL_LOCK to avoid + * the DP inter pair skew issue for at least 10 us + */ + analogix_dp_reset_macro(dp); analogix_dp_set_lane_count(dp, dp->link_train.lane_count); analogix_dp_set_lane_link_training(dp);
Setting the link bandwidth may change the PLL parameters, which will cause the PLL to go out of lock, so make sure to apply the MACRO_RST, which according to the comment is required to be pulsed after the PLL is locked. Signed-off-by: Lucas Stach <l.stach@pengutronix.de> --- .../gpu/drm/bridge/analogix/analogix_dp_core.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-)