[Intel-gfx] [PATCH v2] drm/i915/d12+: Disable DMC firmware flip queue handlers
Lucas De Marchi
lucas.demarchi at intel.com
Thu May 12 22:37:14 UTC 2022
On Thu, May 12, 2022 at 10:47:46PM +0300, Imre Deak wrote:
>On Thu, May 12, 2022 at 10:56:11AM -0700, Lucas De Marchi wrote:
>> On Thu, May 12, 2022 at 12:37:05PM +0300, Imre Deak wrote:
>> > Based on a bspec update the DMC firmware's flip queue handling events
>> > need to be disabled before enabling DC5/6. i915 doesn't use the flip
>> > queue feature atm, so disable it already after loading the firmware.
>> > This removes some overhead of the event handler which runs at a 1 kHz
>> > frequency.
>> >
>> > Bspec: 49193, 72486, 72487
>> >
>> > v2:
>> > - Fix the DMC pipe A register offsets for GEN12.
>> > - Disable the events on DG2 only on pipe A..D .
>> >
>> > Signed-off-by: Imre Deak <imre.deak at intel.com>
>> > Reviewed-by: Anusha Srivatsa <anusha.srivatsa at intel.com> # v1
>> > ---
>> > drivers/gpu/drm/i915/display/intel_dmc.c | 89 ++++++++++++++++++-
>> > drivers/gpu/drm/i915/display/intel_dmc_regs.h | 41 +++++++++
>> > 2 files changed, 129 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c b/drivers/gpu/drm/i915/display/intel_dmc.c
>> > index 257cf662f9f4b..0ede8c86c6ccb 100644
>> > --- a/drivers/gpu/drm/i915/display/intel_dmc.c
>> > +++ b/drivers/gpu/drm/i915/display/intel_dmc.c
>> > @@ -244,9 +244,14 @@ struct stepping_info {
>> > char substepping;
>> > };
>> >
>> > +static bool intel_dmc_has_fw_payload(struct drm_i915_private *i915, int dmc_id)
>>
>> in several places, including this file, we are trying to keep the
>> convention of not using intel_ prefix for non-exported functions.
>>
>> has_dmc_id_fw() here would read better IMO.
>
>Ok.
>
>> > +{
>> > + return i915->dmc.dmc_info[dmc_id].payload;
>> > +}
>> > +
>> > bool intel_dmc_has_payload(struct drm_i915_private *i915)
>> > {
>> > - return i915->dmc.dmc_info[DMC_FW_MAIN].payload;
>> > + return intel_dmc_has_fw_payload(i915, DMC_FW_MAIN);
>> > }
>> >
>> > static const struct stepping_info *
>> > @@ -268,6 +273,81 @@ static void gen9_set_dc_state_debugmask(struct drm_i915_private *dev_priv)
>> > intel_de_posting_read(dev_priv, DC_STATE_DEBUG);
>> > }
>> >
>> > +static void
>> > +disable_simple_flip_queue_event(struct drm_i915_private *i915,
>> > + i915_reg_t ctl_reg, i915_reg_t htp_reg)
>> > +{
>> > + u32 event_ctl;
>> > + u32 event_htp;
>> > +
>> > + event_ctl = intel_de_read(i915, ctl_reg);
>> > + event_htp = intel_de_read(i915, htp_reg);
>> > + if (event_ctl != (DMC_EVT_CTL_ENABLE |
>> > + DMC_EVT_CTL_RECURRING |
>> > + REG_FIELD_PREP(DMC_EVT_CTL_TYPE_MASK,
>> > + DMC_EVT_CTL_TYPE_EDGE_0_1) |
>> > + REG_FIELD_PREP(DMC_EVT_CTL_EVENT_ID_MASK,
>> > + DMC_EVT_CTL_EVENT_ID_CLK_MSEC)) ||
>> > + !event_htp) {
>> > + drm_dbg_kms(&i915->drm,
>> > + "Unexpected DMC event configuration (control %08x htp %08x)\n",
>> > + event_ctl, event_htp);
>> > + return;
>> > + }
>>
>> why are we doing this if we just want to disable? If we will always keep
>> it disabled, then just writing the right values would be simpler.
>
>The requirement to disable flip queues explicitly came only now,
>somewhat as a surprise. Future firmware versions will disable it by
>default, but it's not clear at which point and how the ABI will change
>then. So I'd like to keep the above check for any such ABI change in
>place at least until those plans get clarified to us.
humn... It seems weird to log "Unexpected DMC event... " if we are
expecting that in future it will be disabled. But since it's a debug
message only, it's not a big thing.
Later are you expecting to separate the an if condition like below?
if (!(event_ctl & DMC_EVT_CTL_ENABLE)) {
drm_dbg_kms(&i915->drm, "Skip flip queue disabling: already disabled\n");
return;
}
>
>> > +
>> > + intel_de_write(i915, ctl_reg,
>> > + REG_FIELD_PREP(DMC_EVT_CTL_TYPE_MASK,
>> > + DMC_EVT_CTL_TYPE_EDGE_0_1) |
>> > + REG_FIELD_PREP(DMC_EVT_CTL_EVENT_ID_MASK,
>> > + DMC_EVT_CTL_EVENT_ID_FALSE));
>> > + intel_de_write(i915, htp_reg, 0);
>>
>> matches bspec 72487 and 72486. It looks like we are missing a disable
>> sequence for ADL-P though. Is it a missing documentation or function
>> below should be updated to do nothing on ADL-P?
>
>First I thought ADL-P doesn't use the same 1 kHz event as the other
>platforms, hence no disable sequence is defined by bspec. But looking
>again it also seems to use that just with a different event ID
>('1KHZ_FLIPQ' vs. 'CLK_MSEC', see bspec 67608). I filed a bspec ticket
>and will add the disabling for ADLP as well once that gets clarified.
ok
>
>> > +}
>> > +
>> > +static bool
>> > +get_simple_flip_queue_event_regs(struct drm_i915_private *i915, int dmc_id,
>> > + i915_reg_t *ctl_reg, i915_reg_t *htp_reg)
>> > +{
>> > + switch (dmc_id) {
>> > + case DMC_FW_MAIN:
>> > + if (DISPLAY_VER(i915) == 12) {
>>
>> Shouldn't this be >= 12? but see comment above about ADL-P
>
>It's only D12 platforms that use one event handler running on the main
>DMC for this, all later platforms use one event handler running on each
>pipe DMC, and no flip queue handler running on the main DMC.
ok, this is the PIPEMDC_* vs DMC_* on Display 13 vs 12.
>> > + *ctl_reg = DMC_EVT_CTL(i915, dmc_id, 3);
>> > + *htp_reg = DMC_EVT_HTP(i915, dmc_id, 3);
>>
>> For DG2 the sequence in bspec is:
>>
>> 1. Disable flip queue
>> 2. PIPEDMC_EVT_CTL_2_A/B/C/D = 0x00030100
>> 3. PIPEDMC_EVT_HTP_2_A/B/C/D = 0x00000000
>>
>> where did you get that for main dmc you need to write to CTL_3/HTP_3?
>
>Bspec/72486, and checking the fixed MMIOs in the TGL/RKL firmwares (for
>the above 1kHz events).
yeah, looks good. Kind of same issue I had reading the spec in the
question above. That answers it.
>
>> > +
>> > + return true;
>> > + }
>> > + break;
>> > + case DMC_FW_PIPEA ... DMC_FW_PIPED:
>> > + if (IS_DG2(i915)) {
>> > + *ctl_reg = DMC_EVT_CTL(i915, dmc_id, 2);
>> > + *htp_reg = DMC_EVT_HTP(i915, dmc_id, 2);
>> > +
>> > + return true;
>> > + }
>> > + break;
>> > + }
>> > +
>> > + return false;
>> > +}
>> > +
>> > +static void
>> > +disable_all_simple_flip_queue_events(struct drm_i915_private *i915)
>> > +{
>> > + int dmc_id;
>> > +
>> > + for (dmc_id = 0; dmc_id < DMC_FW_MAX; dmc_id++) {
>> > + i915_reg_t ctl_reg;
>> > + i915_reg_t htp_reg;
>> > +
>> > + if (!intel_dmc_has_fw_payload(i915, dmc_id))
>> > + continue;
>> > +
>> > + if (!get_simple_flip_queue_event_regs(i915, dmc_id, &ctl_reg, &htp_reg))
>> > + continue;
>> > +
>> > + disable_simple_flip_queue_event(i915, ctl_reg, htp_reg);
>> > + }
>> > +}
>>
>> it seems we are mixing "flip queue" and "simple flip queue". Maybe just
>> remove "simple" as it doesn't add much information?
>
>The other variant is called batch flip queue, but can rename this to
>flip_queue.
My preference is to drop "simple", but feel free to keep it if you want.
>
>> > +
>> > /**
>> > * intel_dmc_load_program() - write the firmware from memory to register.
>> > * @dev_priv: i915 drm device.
>> > @@ -308,6 +388,13 @@ void intel_dmc_load_program(struct drm_i915_private *dev_priv)
>> > dev_priv->dmc.dc_state = 0;
>> >
>> > gen9_set_dc_state_debugmask(dev_priv);
>> > +
>> > + /*
>> > + * Flip queue events need to be disabled before enabling DC5/6.
>> > + * i915 doesn't use the flip queue feature, so disable it already
>> > + * here.
>> > + */
>> > + disable_all_simple_flip_queue_events(dev_priv);
>> > }
>> >
>> > void assert_dmc_loaded(struct drm_i915_private *i915)
>> > diff --git a/drivers/gpu/drm/i915/display/intel_dmc_regs.h b/drivers/gpu/drm/i915/display/intel_dmc_regs.h
>> > index d65e698832eb5..43d780148b196 100644
>> > --- a/drivers/gpu/drm/i915/display/intel_dmc_regs.h
>> > +++ b/drivers/gpu/drm/i915/display/intel_dmc_regs.h
>> > @@ -10,6 +10,47 @@
>> >
>> > #define DMC_PROGRAM(addr, i) _MMIO((addr) + (i) * 4)
>> > #define DMC_SSP_BASE_ADDR_GEN9 0x00002FC0
>> > +
>> > +#define _PIPEDMC_REG_MMIO_BASE_A_GEN13 0x5f000
>> > +#define _PIPEDMC_REG_MMIO_BASE_A_GEN12 0x92000
>>
>> no _GEN12/_GEN13 suffix
>
>Why not? Is _ADLP/_TGL ok?
We are not supposed to add GEN<x> anymore as that doesn't make sense for
our gpus anymore. Versions are separated per IP like display, graphics,
media. We went on an effort to rename everything last year. We still
have some, but we should avoid adding more.
yes, using the first platform that uses the register keeps with what's
being used in i915_drv.h
>
>> > +
>> > +#define _PIPEDMC_REG_MMIO_BASE(i915, dmc_id) \
>> > + ((DISPLAY_VER(i915) >= 13 ? _PIPEDMC_REG_MMIO_BASE_A_GEN13 : \
>> > + _PIPEDMC_REG_MMIO_BASE_A_GEN12) + \
>> > + 0x400 * ((dmc_id) - 1))
>> > +
>> > +#define _MAINDMC_REG_MMIO_BASE 0x8f000
>> > +
>> > +#define _DMC_REG_MMIO_BASE(i915, dmc_id) \
>> > + ((dmc_id) == DMC_FW_MAIN ? _MAINDMC_REG_MMIO_BASE : \
>> > + _PIPEDMC_REG_MMIO_BASE(i915, dmc_id))
>> > +
>> > +#define _DMC_REG(i915, dmc_id, reg) \
>> > + ((reg) - _MAINDMC_REG_MMIO_BASE + _DMC_REG_MMIO_BASE(i915, dmc_id))
>> > +
>> > +#define _MAINDMC_EVT_HTP_0 0x8f004
>> > +
>> > +#define DMC_EVT_HTP(i915, dmc_id, handler) \
>> > + _MMIO(_DMC_REG(i915, dmc_id, _MAINDMC_EVT_HTP_0) + 4 * (handler))
>> > +
>> > +#define _MAINDMC_EVT_CTL_0 0x8f034
>>
>> if we were to follow the spec names, we'd rather name
>> _DMC_* for main fw
>> _PIPEDMC_* for others.
>
>Ok.
>
>> > +
>> > +#define DMC_EVT_CTL(i915, dmc_id, handler) \
>> > + _MMIO(_DMC_REG(i915, dmc_id, _MAINDMC_EVT_CTL_0) + 4 * (handler))
>>
>> s/handler/offset/?
>
>There are a number of event handlers each main/pipe DMC can run,
>each of which is configured via its control and HTP register. 'handler'
>refers to such handler instances.
makes sense, it was my lack of understanding on this part of the spec.
>
>> It seems we have to massage the macros everywhere to handle pipe vs
>> main. Given get_simple_flip_queue_event_regs() already handle them
>> separate, I think it would be simpler to just split the macros on DMC_*
>> vs PIPEDMC_*, which would be more inline with the spec too.
>
>There are cases where it's practical being able to loop through all main
>and pipe DMC registers in one go, for instance for clearing all
>event control and HTP registers when reloading the firmware.
humn, I have the impression in most cases the code is cleaner handling
the MAIN DMC separate from the loop on the pipe DMCs. But if you want to
keep them together on the macro, I'm fine.
>
>>
>> Maybe the most important question:
>>
>> with this patch + the patch to load DMC on DG2, do we get the DC5
>> transition to work? It'd be good to submit both together so we can
>> ensure it does.
>
>I think disabling flip queues is the correct thing even w/o considering
>DC5. But yes, on DG2 it happens to fix that. The idea was to merge this
>patch first to get separate CI results and follow up with a change to
>enable DC5 on DG2.
The problem from my pov is avoid merging something just to realize later
there is something wrong we didn't find in the review and having to fix
it up on top.
Anyway, code here looks correct. Feel free to add
Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>
on the next version.
thanks
Lucas De Marchi
>
>> Lucas De Marchi
>>
>> > +
>> > +#define DMC_EVT_CTL_ENABLE REG_BIT(31)
>> > +#define DMC_EVT_CTL_RECURRING REG_BIT(30)
>> > +#define DMC_EVT_CTL_TYPE_MASK REG_GENMASK(17, 16)
>> > +#define DMC_EVT_CTL_TYPE_LEVEL_0 0
>> > +#define DMC_EVT_CTL_TYPE_LEVEL_1 1
>> > +#define DMC_EVT_CTL_TYPE_EDGE_1_0 2
>> > +#define DMC_EVT_CTL_TYPE_EDGE_0_1 3
>> > +
>> > +#define DMC_EVT_CTL_EVENT_ID_MASK REG_GENMASK(15, 8)
>> > +#define DMC_EVT_CTL_EVENT_ID_FALSE 0x01
>> > +/* An event handler scheduled to run at a 1 kHz frequency. */
>> > +#define DMC_EVT_CTL_EVENT_ID_CLK_MSEC 0xbf
>> > +
>> > #define DMC_HTP_ADDR_SKL 0x00500034
>> > #define DMC_SSP_BASE _MMIO(0x8F074)
>> > #define DMC_HTP_SKL _MMIO(0x8F004)
>> > --
>> > 2.30.2
>> >
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