On Thu, 03 Jun 2021, "Manna, Animesh" <animesh.manna@xxxxxxxxx> wrote:
>> -----Original Message-----
>> From: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
>> Sent: Thursday, June 3, 2021 3:10 PM
>> To: Roper, Matthew D <matthew.d.roper@xxxxxxxxx>; intel-
>> gfx@xxxxxxxxxxxxxxxxxxxxx
>> Cc: Manna, Animesh <animesh.manna@xxxxxxxxx>; Navare, Manasi D
>> <manasi.d.navare@xxxxxxxxx>; Kulkarni, Vandita <vandita.kulkarni@xxxxxxxxx>
>> Subject: Re: [CI 15/19] drm/i915/bigjoiner: atomic commit changes
>> for uncompressed joiner
>>
>> On Fri, 14 May 2021, Matt Roper <matthew.d.roper@xxxxxxxxx> wrote:
>> > From: Animesh Manna <animesh.manna@xxxxxxxxx>
>> >
>> > Respective bit for master or slave to be set for uncompressed
>> > bigjoiner in dss_ctl1 register.
>>
>> I was looking at the changes here due to a static checker complaint, and I think
>> there are a number of issues here. Some more serious than others, and some
>> predate the patch.
>>
>> Comments inline.
>>
>> > Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
>> > Signed-off-by: Animesh Manna <animesh.manna@xxxxxxxxx>
>> > Signed-off-by: Clinton Taylor <Clinton.A.Taylor@xxxxxxxxx>
>> > Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
>> > Reviewed-by: Manasi Navare <manasi.d.navare@xxxxxxxxx>
>> > ---
>> > drivers/gpu/drm/i915/display/intel_display.c | 6 +++
>> > drivers/gpu/drm/i915/display/intel_vdsc.c | 40 +++++++++++++++++++-
>> > drivers/gpu/drm/i915/display/intel_vdsc.h | 2 +
>> > drivers/gpu/drm/i915/i915_reg.h | 2 +
>> > 4 files changed, 49 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
>> > b/drivers/gpu/drm/i915/display/intel_display.c
>> > index b5fd721137d3..422b59ebf6dc 100644
>> > --- a/drivers/gpu/drm/i915/display/intel_display.c
>> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
>> > @@ -3411,6 +3411,7 @@ static void icl_ddi_bigjoiner_pre_enable(struct
>> intel_atomic_state *state,
>> > const struct intel_crtc_state
>> *crtc_state) {
>> > struct intel_crtc *master = to_intel_crtc(crtc_state->uapi.crtc);
>> > + struct drm_i915_private *dev_priv = to_i915(master->base.dev);
>> > struct intel_crtc_state *master_crtc_state;
>> > struct drm_connector_state *conn_state;
>> > struct drm_connector *conn;
>> > @@ -3444,6 +3445,9 @@ static void icl_ddi_bigjoiner_pre_enable(struct
>> intel_atomic_state *state,
>> > /* and DSC on slave */
>> > intel_dsc_enable(NULL, crtc_state);
>> > }
>> > +
>> > + if (DISPLAY_VER(dev_priv) >= 13)
>> > + intel_uncompressed_joiner_enable(crtc_state);
>> > }
>> >
>> > static void hsw_crtc_enable(struct intel_atomic_state *state, @@
>> > -6250,6 +6254,8 @@ static bool hsw_get_pipe_config(struct intel_crtc *crtc,
>> > }
>> >
>> > intel_dsc_get_config(pipe_config);
>> > + if (DISPLAY_VER(dev_priv) >= 13 && !pipe_config-
>> >dsc.compression_enable)
>> > + intel_uncompressed_joiner_get_config(pipe_config);
>> >
>> > if (!active) {
>> > /* bigjoiner slave doesn't enable transcoder */ diff --git
>> > a/drivers/gpu/drm/i915/display/intel_vdsc.c
>> > b/drivers/gpu/drm/i915/display/intel_vdsc.c
>> > index adcd6752f919..efc3184d8315 100644
>> > --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
>> > +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
>> > @@ -1021,6 +1021,22 @@ static i915_reg_t dss_ctl2_reg(const struct
>> intel_crtc_state *crtc_state)
>> > return is_pipe_dsc(crtc_state) ? ICL_PIPE_DSS_CTL2(pipe) : DSS_CTL2;
>> > }
>> >
>> > +void intel_uncompressed_joiner_enable(const struct intel_crtc_state
>> > +*crtc_state)
>>
>> Naming. Basically for any new function, the function name prefix should match
>> the file name. intel_vdsc.[ch] should have functions prefixed intel_vdsc_*(). This
>> is where we're headed to increase clarity.
>>
>> intel_uncompressed_*() is something completely different.
>>
>> Granted, here we already have intel_dsc_*() in intel_vdsc.c. We should probably
>> stick with intel_dsc_*(). A possible function or file rename is not out of the
>> question, but that's a separate matter.
>
> As there is not separate register for uncompressed joiner, using bitfield of dsc register only the function name can be changed to intel_dsc_uncompressed_joiner_enable().
>
>>
>> > +{
>> > + struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>> > + struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
>> > + u32 dss_ctl1_val = 0;
>> > +
>> > + if (crtc_state->bigjoiner && !crtc_state->dsc.compression_enable) {
>> > + if (crtc_state->bigjoiner_slave)
>> > + dss_ctl1_val |= UNCOMPRESSED_JOINER_SLAVE;
>> > + else
>> > + dss_ctl1_val |= UNCOMPRESSED_JOINER_MASTER;
>> > +
>> > + intel_de_write(dev_priv, dss_ctl1_reg(crtc_state), dss_ctl1_val);
>> > + }
>> > +}
>> > +
>> > void intel_dsc_enable(struct intel_encoder *encoder,
>> > const struct intel_crtc_state *crtc_state) { @@ -1060,13
>> > +1076,35 @@ void intel_dsc_disable(const struct intel_crtc_state
>> *old_crtc_state)
>> > struct intel_crtc *crtc = to_intel_crtc(old_crtc_state->uapi.crtc);
>> > struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
>> >
>> > - if (!old_crtc_state->dsc.compression_enable)
>> > + if (!(old_crtc_state->dsc.compression_enable &&
>> > + old_crtc_state->bigjoiner))
>>
>> This fails to disable compression if we only have compression but no bigjoiner,
>> which is the more common case!
>>
>> See also:
>>
>> https://gitlab.freedesktop.org/drm/intel/-/issues/3537
>> https://patchwork.freedesktop.org/patch/msgid/20210603065356.15435-1-
>> vandita.kulkarni@xxxxxxxxx
>>
>
> We may need to remove both the condition check.
> In uncompressed bigjoiner, compression_enable flag will be 0 and may not clear the bit of dss_ctl1_reg.
> So can we remove both the checks, hoping it will not harm reseting the register even if it is not set.
Now it only disables if *both* were enabled. It needs to be disabled if
*either* was enabled. But if *neither* was enabled, we don't need to do
this.
>
>> > return;
>> >
>> > intel_de_write(dev_priv, dss_ctl1_reg(old_crtc_state), 0);
>> > intel_de_write(dev_priv, dss_ctl2_reg(old_crtc_state), 0); }
>> >
>> > +void intel_uncompressed_joiner_get_config(struct intel_crtc_state
>> > +*crtc_state) {
>> > + struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>> > + struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
>> > + u32 dss_ctl1;
>> > +
>> > + dss_ctl1 = intel_de_read(dev_priv, dss_ctl1_reg(crtc_state));
>> > + if (dss_ctl1 & UNCOMPRESSED_JOINER_MASTER) {
>> > + crtc_state->bigjoiner = true;
>> > + if (!WARN_ON(INTEL_NUM_PIPES(dev_priv) == crtc->pipe + 1))
>> > + crtc_state->bigjoiner_linked_crtc =
>> > + intel_get_crtc_for_pipe(dev_priv, crtc->pipe +
>> 1);
>> > + } else if (dss_ctl1 & UNCOMPRESSED_JOINER_SLAVE) {
>> > + crtc_state->bigjoiner = true;
>> > + crtc_state->bigjoiner_slave = true;
>> > + if (!WARN_ON(crtc->pipe == PIPE_A))
>> > + crtc_state->bigjoiner_linked_crtc =
>> > + intel_get_crtc_for_pipe(dev_priv, crtc->pipe -
>> 1);
>> > + }
>>
>> Nitpick: This duplicates a bunch of logic for figuring out master/slave.
>>
>> The static checker warning was about crtc->pipe + 1 usage. Since
>> INTEL_NUM_PIPES() looks at the hamming weight of i915->pipe_mask, the
>> checker has a hard time figuring out it does not overflow
>> i915->pipe_to_crtc_mapping[] in intel_get_crtc_for_pipe().
>>
>> So here in intel_vdsc.c the checks are for overflowing/underflowing the pipe
>> range. In intel_get_crtc_for_pipe() there's a check for the pipe actually existing -
>> the pipe numbering might not be contiguous.
>>
>> Superficially the static checker warning is bogus, as in we won't overflow
>> anything. However, deep down there are issues in the consistency of the checks
>> and how to handle non-contigouous pipe numbering.
>>
>> Indeed, this does not *need* the number. We should figure out the next *crtc*,
>> not the next pipe *number*, which may or may not be pipe + 1.
>
> dss_ctl1 value is used to identify master or slave crtc. If needed WARN_ON check can be removed... but pipe enum values like PIPE_A/B/C/D is used to get the master/slave crtc and always bigjoiner is possible with two adjacent pipes.
I sent the patch for this and you reviewed it... but are adjacent pipes
a requirement for bigjoiner? Would e.g. A+C work if B was fused off? If
not, my patch 2/2 is incorrect.
BR,
Jani.
>
> Regards,
> Animesh
>
>>
>>
>> BR,
>> Jani.
>>
>> > +}
>> > +
>> > void intel_dsc_get_config(struct intel_crtc_state *crtc_state) {
>> > struct drm_dsc_config *vdsc_cfg = &crtc_state->dsc.config; diff
>> > --git a/drivers/gpu/drm/i915/display/intel_vdsc.h
>> > b/drivers/gpu/drm/i915/display/intel_vdsc.h
>> > index 65d301c23580..fe4d45561253 100644
>> > --- a/drivers/gpu/drm/i915/display/intel_vdsc.h
>> > +++ b/drivers/gpu/drm/i915/display/intel_vdsc.h
>> > @@ -12,11 +12,13 @@ struct intel_encoder; struct intel_crtc_state;
>> >
>> > bool intel_dsc_source_support(const struct intel_crtc_state
>> > *crtc_state);
>> > +void intel_uncompressed_joiner_enable(const struct intel_crtc_state
>> > +*crtc_state);
>> > void intel_dsc_enable(struct intel_encoder *encoder,
>> > const struct intel_crtc_state *crtc_state); void
>> > intel_dsc_disable(const struct intel_crtc_state *crtc_state); int
>> > intel_dsc_compute_params(struct intel_encoder *encoder,
>> > struct intel_crtc_state *pipe_config);
>> > +void intel_uncompressed_joiner_get_config(struct intel_crtc_state
>> > +*crtc_state);
>> > void intel_dsc_get_config(struct intel_crtc_state *crtc_state); enum
>> > intel_display_power_domain intel_dsc_power_domain(const struct
>> > intel_crtc_state *crtc_state); diff --git
>> > a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
>> > index 31bc413dbba1..dd6e0bae9573 100644
>> > --- a/drivers/gpu/drm/i915/i915_reg.h
>> > +++ b/drivers/gpu/drm/i915/i915_reg.h
>> > @@ -11493,6 +11493,8 @@ enum skl_power_gate {
>> > #define SPLITTER_CONFIGURATION_MASK REG_GENMASK(26, 25)
>> > #define SPLITTER_CONFIGURATION_2_SEGMENT
>> REG_FIELD_PREP(SPLITTER_CONFIGURATION_MASK, 0)
>> > #define SPLITTER_CONFIGURATION_4_SEGMENT
>> REG_FIELD_PREP(SPLITTER_CONFIGURATION_MASK, 1)
>> > +#define UNCOMPRESSED_JOINER_MASTER (1 << 21)
>> > +#define UNCOMPRESSED_JOINER_SLAVE (1 << 20)
>> >
>> > #define _ICL_PIPE_DSS_CTL2_PB 0x78204
>> > #define _ICL_PIPE_DSS_CTL2_PC 0x78404
>>
>> --
>> Jani Nikula, Intel Open Source Graphics Center
--
Jani Nikula, Intel Open Source Graphics Center
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