Message ID | 20211006204937.30774-9-ville.syrjala@linux.intel.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | drm/i915: DP per-lane drive settings for icl+ | expand |
On Wed, 2021-10-06 at 23:49 +0300, Ville Syrjala wrote: > From: Ville Syrjälä <ville.syrjala@linux.intel.com> > > Prepare for per-lane drive settings by querying the desired vswing > level per-lane. > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> > --- > drivers/gpu/drm/i915/display/intel_ddi.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c > index aa789cabc55b..4c400f0e7347 100644 > --- a/drivers/gpu/drm/i915/display/intel_ddi.c > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c > @@ -1039,7 +1039,6 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > const struct intel_crtc_state *crtc_state) > { > struct drm_i915_private *dev_priv = to_i915(encoder->base.dev); > - int level = intel_ddi_level(encoder, crtc_state, 0); > const struct intel_ddi_buf_trans *trans; > enum phy phy = intel_port_to_phy(dev_priv, encoder->port); > int n_entries, ln; > @@ -1069,6 +1068,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > > /* Program PORT_TX_DW2 */ > for (ln = 0; ln < 4; ln++) { > + int level = intel_ddi_level(encoder, crtc_state, ln); > + > val = intel_de_read(dev_priv, ICL_PORT_TX_DW2_LN(ln, phy)); > val &= ~(SWING_SEL_LOWER_MASK | SWING_SEL_UPPER_MASK | > RCOMP_SCALAR_MASK); > @@ -1082,6 +1083,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > /* Program PORT_TX_DW4 */ > /* We cannot write to GRP. It would overwrite individual loadgen. */ > for (ln = 0; ln < 4; ln++) { > + int level = intel_ddi_level(encoder, crtc_state, ln); > + > val = intel_de_read(dev_priv, ICL_PORT_TX_DW4_LN(ln, phy)); > val &= ~(POST_CURSOR_1_MASK | POST_CURSOR_2_MASK | > CURSOR_COEFF_MASK); > @@ -1093,6 +1096,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > > /* Program PORT_TX_DW7 */ > for (ln = 0; ln < 4; ln++) { > + int level = intel_ddi_level(encoder, crtc_state, ln); > + > val = intel_de_read(dev_priv, ICL_PORT_TX_DW7_LN(ln, phy)); > val &= ~N_SCALAR_MASK; > val |= N_SCALAR(trans->entries[level].icl.dw7_n_scalar); The cover letter or one of the earlier patches should have some explanation about the reasons of this the group to lane conversion. Reading one of the later patches I understood is because DP 2.0 allows different level per lane but would be nice to know for sure the reason. What if it is only using 2 lanes? Programming disabled lanes will cause any issue?
On Fri, Oct 29, 2021 at 09:57:02PM +0000, Souza, Jose wrote: > On Wed, 2021-10-06 at 23:49 +0300, Ville Syrjala wrote: > > From: Ville Syrjälä <ville.syrjala@linux.intel.com> > > > > Prepare for per-lane drive settings by querying the desired vswing > > level per-lane. > > > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> > > --- > > drivers/gpu/drm/i915/display/intel_ddi.c | 7 ++++++- > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c > > index aa789cabc55b..4c400f0e7347 100644 > > --- a/drivers/gpu/drm/i915/display/intel_ddi.c > > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c > > @@ -1039,7 +1039,6 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > > const struct intel_crtc_state *crtc_state) > > { > > struct drm_i915_private *dev_priv = to_i915(encoder->base.dev); > > - int level = intel_ddi_level(encoder, crtc_state, 0); > > const struct intel_ddi_buf_trans *trans; > > enum phy phy = intel_port_to_phy(dev_priv, encoder->port); > > int n_entries, ln; > > @@ -1069,6 +1068,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > > > > /* Program PORT_TX_DW2 */ > > for (ln = 0; ln < 4; ln++) { > > + int level = intel_ddi_level(encoder, crtc_state, ln); > > + > > val = intel_de_read(dev_priv, ICL_PORT_TX_DW2_LN(ln, phy)); > > val &= ~(SWING_SEL_LOWER_MASK | SWING_SEL_UPPER_MASK | > > RCOMP_SCALAR_MASK); > > @@ -1082,6 +1083,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > > /* Program PORT_TX_DW4 */ > > /* We cannot write to GRP. It would overwrite individual loadgen. */ > > for (ln = 0; ln < 4; ln++) { > > + int level = intel_ddi_level(encoder, crtc_state, ln); > > + > > val = intel_de_read(dev_priv, ICL_PORT_TX_DW4_LN(ln, phy)); > > val &= ~(POST_CURSOR_1_MASK | POST_CURSOR_2_MASK | > > CURSOR_COEFF_MASK); > > @@ -1093,6 +1096,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > > > > /* Program PORT_TX_DW7 */ > > for (ln = 0; ln < 4; ln++) { > > + int level = intel_ddi_level(encoder, crtc_state, ln); > > + > > val = intel_de_read(dev_priv, ICL_PORT_TX_DW7_LN(ln, phy)); > > val &= ~N_SCALAR_MASK; > > val |= N_SCALAR(trans->entries[level].icl.dw7_n_scalar); > > The cover letter or one of the earlier patches should have some explanation about the reasons of this the group to lane conversion. They do say it's for per-lane drive setings. Not rally sure what to add to that. > Reading one of the later patches I understood is because DP 2.0 allows different level per lane but would be nice to know for sure the reason. It has always been a feature of DP, we just never implemented it for whatever reason. > > What if it is only using 2 lanes? Programming disabled lanes will cause any issue? Depends on whether the registers are available or not. For CHV I know the unused lanes will be fully powered off and you can't actually access the registers (and vlv_dpio_read() will actually WARN when it sees the ~0 value from an inaccessible register). For later platforms I don't actually know what happens. We don't have an equivalent of that CHV WARN but I would hope that we'd get an unclaimed reg warning if the register is inaccessible. Although I suppose there's isn't any real harm in poking inaccssible registers. The reads should just return all 0s or all 1s, and the writes go to /dev/null.
On Mon, 2021-11-01 at 12:11 +0200, Ville Syrjälä wrote: > On Fri, Oct 29, 2021 at 09:57:02PM +0000, Souza, Jose wrote: > > On Wed, 2021-10-06 at 23:49 +0300, Ville Syrjala wrote: > > > From: Ville Syrjälä <ville.syrjala@linux.intel.com> > > > > > > Prepare for per-lane drive settings by querying the desired vswing > > > level per-lane. > > > > > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> > > > --- > > > drivers/gpu/drm/i915/display/intel_ddi.c | 7 ++++++- > > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c > > > index aa789cabc55b..4c400f0e7347 100644 > > > --- a/drivers/gpu/drm/i915/display/intel_ddi.c > > > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c > > > @@ -1039,7 +1039,6 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > > > const struct intel_crtc_state *crtc_state) > > > { > > > struct drm_i915_private *dev_priv = to_i915(encoder->base.dev); > > > - int level = intel_ddi_level(encoder, crtc_state, 0); > > > const struct intel_ddi_buf_trans *trans; > > > enum phy phy = intel_port_to_phy(dev_priv, encoder->port); > > > int n_entries, ln; > > > @@ -1069,6 +1068,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > > > > > > /* Program PORT_TX_DW2 */ > > > for (ln = 0; ln < 4; ln++) { > > > + int level = intel_ddi_level(encoder, crtc_state, ln); > > > + > > > val = intel_de_read(dev_priv, ICL_PORT_TX_DW2_LN(ln, phy)); > > > val &= ~(SWING_SEL_LOWER_MASK | SWING_SEL_UPPER_MASK | > > > RCOMP_SCALAR_MASK); > > > @@ -1082,6 +1083,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > > > /* Program PORT_TX_DW4 */ > > > /* We cannot write to GRP. It would overwrite individual loadgen. */ > > > for (ln = 0; ln < 4; ln++) { > > > + int level = intel_ddi_level(encoder, crtc_state, ln); > > > + > > > val = intel_de_read(dev_priv, ICL_PORT_TX_DW4_LN(ln, phy)); > > > val &= ~(POST_CURSOR_1_MASK | POST_CURSOR_2_MASK | > > > CURSOR_COEFF_MASK); > > > @@ -1093,6 +1096,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, > > > > > > /* Program PORT_TX_DW7 */ > > > for (ln = 0; ln < 4; ln++) { > > > + int level = intel_ddi_level(encoder, crtc_state, ln); > > > + > > > val = intel_de_read(dev_priv, ICL_PORT_TX_DW7_LN(ln, phy)); > > > val &= ~N_SCALAR_MASK; > > > val |= N_SCALAR(trans->entries[level].icl.dw7_n_scalar); > > > > The cover letter or one of the earlier patches should have some explanation about the reasons of this the group to lane conversion. > > They do say it's for per-lane drive setings. Not rally sure what to add > to that. > > > Reading one of the later patches I understood is because DP 2.0 allows different level per lane but would be nice to know for sure the reason. > > It has always been a feature of DP, we just never implemented it for > whatever reason. > > > > > What if it is only using 2 lanes? Programming disabled lanes will cause any issue? > > Depends on whether the registers are available or not. For CHV I know > the unused lanes will be fully powered off and you can't actually access > the registers (and vlv_dpio_read() will actually WARN when it sees the > ~0 value from an inaccessible register). For later platforms I don't > actually know what happens. We don't have an equivalent of that CHV WARN > but I would hope that we'd get an unclaimed reg warning if the register > is inaccessible. > > Although I suppose there's isn't any real harm in poking inaccssible > registers. The reads should just return all 0s or all 1s, and the > writes go to /dev/null. > Fair enough. Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c index aa789cabc55b..4c400f0e7347 100644 --- a/drivers/gpu/drm/i915/display/intel_ddi.c +++ b/drivers/gpu/drm/i915/display/intel_ddi.c @@ -1039,7 +1039,6 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, const struct intel_crtc_state *crtc_state) { struct drm_i915_private *dev_priv = to_i915(encoder->base.dev); - int level = intel_ddi_level(encoder, crtc_state, 0); const struct intel_ddi_buf_trans *trans; enum phy phy = intel_port_to_phy(dev_priv, encoder->port); int n_entries, ln; @@ -1069,6 +1068,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, /* Program PORT_TX_DW2 */ for (ln = 0; ln < 4; ln++) { + int level = intel_ddi_level(encoder, crtc_state, ln); + val = intel_de_read(dev_priv, ICL_PORT_TX_DW2_LN(ln, phy)); val &= ~(SWING_SEL_LOWER_MASK | SWING_SEL_UPPER_MASK | RCOMP_SCALAR_MASK); @@ -1082,6 +1083,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, /* Program PORT_TX_DW4 */ /* We cannot write to GRP. It would overwrite individual loadgen. */ for (ln = 0; ln < 4; ln++) { + int level = intel_ddi_level(encoder, crtc_state, ln); + val = intel_de_read(dev_priv, ICL_PORT_TX_DW4_LN(ln, phy)); val &= ~(POST_CURSOR_1_MASK | POST_CURSOR_2_MASK | CURSOR_COEFF_MASK); @@ -1093,6 +1096,8 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder, /* Program PORT_TX_DW7 */ for (ln = 0; ln < 4; ln++) { + int level = intel_ddi_level(encoder, crtc_state, ln); + val = intel_de_read(dev_priv, ICL_PORT_TX_DW7_LN(ln, phy)); val &= ~N_SCALAR_MASK; val |= N_SCALAR(trans->entries[level].icl.dw7_n_scalar);