Re: [PATCH v5] drm/i915/icl: Enhanced execution list support

Mika Kuoppala
2018-01-22T15:08:31Z

Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com> writes:

> On 19/01/18 05:05, Mika Kuoppala wrote:
>> Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com> writes:
>>
>>> From: Thomas Daniel <thomas.daniel@intel.com>
>>>
>>> Enhanced Execlists is an upgraded version of execlists which supports
>>> up to 8 ports. The lrcs to be submitted are written to a submit queue,
>>> which is then loaded on the HW. When writing to the ELSP register, the
>>> lrcs are written cyclically in the queue from position 0 to position 7.
>>> Alternatively, it is possible to write directly in the individual
>>> positions of the queue using the ELSQ registers. To be able to re-use
>>> all the existing code we're using the latter method and we're currently
>>> limiting ourself to only using 2 elements.
>>>
>>> The preemption flow is sligthly different with enhanced execlists, so
>>> this patch turns preemption off temporarily for Gen11+ while we wait for
>>> the new mechanism to land.
>>>
>>> v2: Rebase.
>>> v3: Switch from !IS_GEN11 to GEN < 11 (Daniele Ceraolo Spurio).
>>> v4: Use the elsq registers instead of elsp. (Daniele Ceraolo Spurio)
>>> v5: Reword commit, rename regs to be closer to specs, turn off
>>> preemption (Daniele), reuse engine->execlists.elsp (Chris)
>>>
>>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>>> Signed-off-by: Thomas Daniel <thomas.daniel@intel.com>
>>> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
>>> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>>
>> Was going to adopt this patch from Rodrigo but you were faster.
>>
>> I choose to stash the elsq and use it as a gen11 vs rest toggle:
>>
>> Relevant bits:
>>
>> +static inline void write_port(struct intel_engine_execlists * const execlists,
>> + unsigned int n,
>> + u64 desc)
>> +{
>> + if (execlists->elsq)
>> + gen11_elsq_write(desc, n, execlists->elsq);
>> + else
>> + gen8_elsp_write(desc, execlists->elsp);
>> +}
>> +
>> +static inline void submit_ports(struct intel_engine_execlists * const execlists)
>> +{
>> + /* for gen11+ we need to manually load the submit queue */
>> + if (execlists->elsq) {
>> + struct intel_engine_cs *engine =
>> + container_of(execlists,
>> + struct intel_engine_cs,
>> + execlists);
>> + struct drm_i915_private *dev_priv = engine->i915;
>> +
>> + I915_WRITE_FW(RING_ELCR(engine), ELCR_LOAD);
>> + }
>> +}
>> +
>>
>
> I was undecided about hiding the code in sub-functions because of the
> pre-emption path. There is no need in gen11 to inject a context to
> preempt to idle, so the inject_preempt function will be pre-gen11 only
> and therefore I'd prefer to keep a direct call to elsp_write there. IMHO
> it'd be cleaner to have similar code in both places, hence the
> open-coding. This said, I'd be happy to change it like you proposed if
> there is a general preference to abstract things a bit in the shared
> path even if the pre-emption path stays different.
>

Please don't change. I did the more abstract version before
learning that gen11 don't need the special preempt switch.

> Regarding using execlists->elsq as a toggle, I was thinking that we
> could have a device info flag instead, so we could use it even before
> setting execlists->elsq. Any preference on this?

has_logical_ring_elsq? Doesn't taste bad.

> Thanks,
> Daniele
>
> P.S. If you want to take over feel free to send an updated patch ;)
>

No need to take over, I thought it was orphaned patch :)

-Mika

>> ...
>> -Mika
>>
>>> ---
>>> drivers/gpu/drm/i915/i915_drv.h | 5 ++++-
>>> drivers/gpu/drm/i915/intel_lrc.c | 35 ++++++++++++++++++++++++++++-----
>>> drivers/gpu/drm/i915/intel_lrc.h | 3 +++
>>> drivers/gpu/drm/i915/intel_ringbuffer.h | 6 ++++--
>>> 4 files changed, 41 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>>> index c42015b..3163543 100644
>>> --- a/drivers/gpu/drm/i915/i915_drv.h
>>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>>> @@ -2738,8 +2738,11 @@ static inline unsigned int i915_sg_segment_size(void)
>>>
>>> #define HAS_LOGICAL_RING_CONTEXTS(dev_priv) \
>>> ((dev_priv)->info.has_logical_ring_contexts)
>>> +
>>> +/* XXX: Preemption disabled for Gen11+ until support for new flow lands */
>>> #define HAS_LOGICAL_RING_PREEMPTION(dev_priv) \
>>> - ((dev_priv)->info.has_logical_ring_preemption)
>>> + ((dev_priv)->info.has_logical_ring_preemption && \
>>> + INTEL_GEN(dev_priv) < 11)
>>>
>>> #define HAS_EXECLISTS(dev_priv) HAS_LOGICAL_RING_CONTEXTS(dev_priv)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
>>> index ff25f20..67ad7c9 100644
>>> --- a/drivers/gpu/drm/i915/intel_lrc.c
>>> +++ b/drivers/gpu/drm/i915/intel_lrc.c
>>> @@ -428,11 +428,24 @@ static inline void elsp_write(u64 desc, u32 __iomem *elsp)
>>> writel(lower_32_bits(desc), elsp);
>>> }
>>>
>>> +static inline void elsqc_write(u64 desc, u32 __iomem *elsqc, u32 port)
>>> +{
>>> + writel(lower_32_bits(desc), elsqc + port * 2);
>>> + writel(upper_32_bits(desc), elsqc + port * 2 + 1);
>>> +}
>>> +
>>> static void execlists_submit_ports(struct intel_engine_cs *engine)
>>> {
>>> + struct drm_i915_private *dev_priv = engine->i915;
>>> struct execlist_port *port = engine->execlists.port;
>>> unsigned int n;
>>>
>>> + /*
>>> + * Gen11+ note: the submit queue is not cleared after being submitted
>>> + * to the HW so we need to make sure we always clean it up. This is
>>> + * currently ensured by the fact that we always write the same number
>>> + * of elsq entries, keep this in mind before changing the loop below.
>>> + */
>>> for (n = execlists_num_ports(&engine->execlists); n--; ) {
>>> struct drm_i915_gem_request *rq;
>>> unsigned int count;
>>> @@ -456,8 +469,16 @@ static void execlists_submit_ports(struct intel_engine_cs *engine)
>>> desc = 0;
>>> }
>>>
>>> - elsp_write(desc, engine->execlists.elsp);
>>> + if (INTEL_GEN(dev_priv) >= 11)
>>> + elsqc_write(desc, engine->execlists.els, n);
>>> + else
>>> + elsp_write(desc, engine->execlists.els);
>>> }
>>> +
>>> + /* for gen11+ we need to manually load the submit queue */
>>> + if (INTEL_GEN(dev_priv) >= 11)
>>> + I915_WRITE_FW(RING_EXECLIST_CONTROL(engine), EL_CTRL_LOAD);
>>> +
>>> execlists_clear_active(&engine->execlists, EXECLISTS_ACTIVE_HWACK);
>>> }
>>>
>>> @@ -506,9 +527,9 @@ static void inject_preempt_context(struct intel_engine_cs *engine)
>>>
>>> GEM_TRACE("%s\n", engine->name);
>>> for (n = execlists_num_ports(&engine->execlists); --n; )
>>> - elsp_write(0, engine->execlists.elsp);
>>> + elsp_write(0, engine->execlists.els);
>>>
>>> - elsp_write(ce->lrc_desc, engine->execlists.elsp);
>>> + elsp_write(ce->lrc_desc, engine->execlists.els);
>>> execlists_clear_active(&engine->execlists, EXECLISTS_ACTIVE_HWACK);
>>> }
>>>
>>> @@ -2016,8 +2037,12 @@ static int logical_ring_init(struct intel_engine_cs *engine)
>>> if (ret)
>>> goto error;
>>>
>>> - engine->execlists.elsp =
>>> - engine->i915->regs + i915_mmio_reg_offset(RING_ELSP(engine));
>>> + if (INTEL_GEN(engine->i915) >= 11)
>>> + engine->execlists.els = engine->i915->regs +
>>> + i915_mmio_reg_offset(RING_EXECLIST_SQ_CONTENTS(engine));
>>> + else
>>> + engine->execlists.els = engine->i915->regs +
>>> + i915_mmio_reg_offset(RING_ELSP(engine));
>>>
>>> return 0;
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h
>>> index 6d4f9b9..3ab4266 100644
>>> --- a/drivers/gpu/drm/i915/intel_lrc.h
>>> +++ b/drivers/gpu/drm/i915/intel_lrc.h
>>> @@ -38,6 +38,9 @@
>>> #define CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT (1 << 0)
>>> #define CTX_CTRL_RS_CTX_ENABLE (1 << 1)
>>> #define RING_CONTEXT_STATUS_BUF_BASE(engine) _MMIO((engine)->mmio_base + 0x370)
>>> +#define RING_EXECLIST_SQ_CONTENTS(engine) _MMIO((engine)->mmio_base + 0x510)
>>> +#define RING_EXECLIST_CONTROL(engine) _MMIO((engine)->mmio_base + 0x550)
>>> +#define EL_CTRL_LOAD (1 << 0)
>>> #define RING_CONTEXT_STATUS_BUF_LO(engine, i) _MMIO((engine)->mmio_base + 0x370 + (i) * 8)
>>> #define RING_CONTEXT_STATUS_BUF_HI(engine, i) _MMIO((engine)->mmio_base + 0x370 + (i) * 8 + 4)
>>> #define RING_CONTEXT_STATUS_PTR(engine) _MMIO((engine)->mmio_base + 0x3a0)
>>> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
>>> index c5ff203..d36bb73 100644
>>> --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
>>> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
>>> @@ -200,9 +200,11 @@ struct intel_engine_execlists {
>>> bool no_priolist;
>>>
>>> /**
>>> - * @elsp: the ExecList Submission Port register
>>> + * @els: gen-specific execlist submission register
>>> + * set to the ExecList Submission Port (elsp) register pre-Gen11 and to
>>> + * the ExecList Submission Queue Contents register array for Gen11+
>>> */
>>> - u32 __iomem *elsp;
>>> + u32 __iomem *els;
>>>
>>> /**
>>> * @port: execlist port states
>>> --
>>> 1.9.1
>>>
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