Re: [PATCH 00/15] Batch submission via GuC

From: Daniel Vetter <daniel@ffwll.ch>
To: Dave Gordon <david.s.gordon@intel.com>
Cc: Vinit Azad <vinit.azad@intel.com>,
	intel-gfx@lists.freedesktop.org, Ben Widawsky <ben@bwidawsk.net>
Subject: Re: [PATCH 00/15] Batch submission via GuC
Date: Wed, 17 Jun 2015 14:43:38 +0200	[thread overview]
Message-ID: <20150617124338.GV23637@phenom.ffwll.local> (raw)
In-Reply-To: <1434393394-21002-1-git-send-email-david.s.gordon@intel.com>

On Mon, Jun 15, 2015 at 07:36:18PM +0100, Dave Gordon wrote:
> This patch series enables command submission via the GuC. In this mode,
> instead of the host CPU driving the execlist port directly, it hands
> over work items to the GuC, using a doorbell mechanism to tell the GuC
> that new items have been added to its work queue. The GuC then dispatches
> contexts to the various GPU engines, and manages the resulting context-
> switch interrupts. Completion of a batch is however still signalled to
> the CPU; the GuC is not involved in handling user interrupts.
> 
> There are three subsequences within the patch series:
> 
>   drm/i915: Add i915_gem_object_write() to i915_gem.c
>   drm/i915: Embedded microcontroller (uC) firmware loading support
> 
> These first two patches provide a generic framework for fetching the
> firmware that may be required by any embedded microcontroller from a
> file, using an asynchronous thread so that driver initialisation can
> continue while the firmware is being fetched. It is hoped that this
> framework is sufficiently general that it can be used for all curent
> and future microcontrollers.
> 
>   drm/i915: Add GuC-related module parameters
>   drm/i915: Add GuC-related header files
>   drm/i915: GuC-specific firmware loader
>   drm/i915: Debugfs interface to read GuC load status

Does that include all the nifty power management stuff GuC does?

> These four patches complete the GuC loader. At this point in the sequence
> we can load and activate the GuC firmware, but not submit any batches
> through it. (This is nonetheless a potentially useful state, as the GuC
> can do other useful work even when not handling batch submissions).
> 
>   drm/i915: Defer default hardware context initialisation until first
>   drm/i915: Move execlists defines from .c to .h
>   drm/i915: GuC submission setup, phase 1
>   drm/i915: Enable GuC firmware log
>   drm/i915: Implementation of GuC client
>   drm/i915: Interrupt routing for GuC submission
>   drm/i915: Integrate GuC-based command submission
>   drm/i915: Debugfs interface for GuC submission statistics
>   Documentation/drm: kerneldoc for GuC
>   drm/i915: Enable GuC submission, where supported
> 
> In the final section, we implement the GuC submission mechanism, link
> it into the (execlist-based) submission path, and finally enable it
> (on supported platforms). On platforms where there is no GuC, or if
> the GuC firmware cannot be found or is invalid, batch submission will
> revert to using the execlist mechanism directly.

I thought we had some perf data showing that GuC is now faster than
execbuf ... Where's that?

> The GuC firmware itself is not included in this patchset; it is or will
> be available for download from https://01.org/linuxgraphics/downloads/
> This driver works with and requires GuC firmware revision 3.x. It will
> not work with any firmware version 1.x, as the GuC protocol in those
> revisions was incompatible and is no longer supported.
> 
> Prerequisites: GuC submission will expose existing inadequacies in
> some of the existing codepaths unless certain other patches are applied.
> In particular we will require some version of Michel Thierry's patch
>   drm/i915/lrc: Update PDPx registers with lri commands
> (because the GuC support light-restore, which execlist mode doesn't),
> and my own 
>   drm/i915: Allocate OLR more safely (workaround until OLR goes away)
> because otherwise the changed timing means that there is an increased

s/timing/much reduced ring space I presume?

> risk of writing to a ringbuffer that is not currently pinned & mapped,
> causing a kernel OOPS.

Cheers, Daniel

> 
> Alex Dai (10):
>   drm/i915: Add i915_gem_object_write() to i915_gem.c
>   drm/i915: Add GuC-related module parameters
>   drm/i915: Add GuC-related header files
>   drm/i915: GuC-specific firmware loader
>   drm/i915: Debugfs interface to read GuC load status
>   drm/i915: GuC submission setup, phase 1
>   drm/i915: Enable GuC firmware log
>   drm/i915: Implementation of GuC client
>   drm/i915: Integrate GuC-based command submission
>   Documentation/drm: kerneldoc for GuC
> 
> Dave Gordon (5):
>   drm/i915: Embedded microcontroller (uC) firmware loading support
>   drm/i915: Defer default hardware context initialisation until first
>   drm/i915: Interrupt routing for GuC submission
>   drm/i915: Debugfs interface for GuC submission statistics
>   drm/i915: Enable GuC submission, where supported
> 
> Michael H. Nguyen (1):
>   drm/i915: Move execlists defines from .c to .h
> 
> Ben Widawsky
> Vinit Azad
>   created the original versions on which some of these patches are based.
> 
>  Documentation/DocBook/drm.tmpl             |   19 +
>  drivers/gpu/drm/i915/Makefile              |    7 +
>  drivers/gpu/drm/i915/i915_debugfs.c        |  109 +++-
>  drivers/gpu/drm/i915/i915_dma.c            |    4 +
>  drivers/gpu/drm/i915/i915_drv.h            |   17 +
>  drivers/gpu/drm/i915/i915_gem.c            |   39 +-
>  drivers/gpu/drm/i915/i915_gem_context.c    |   52 +-
>  drivers/gpu/drm/i915/i915_guc_submission.c |  873 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/i915_irq.c            |   48 ++
>  drivers/gpu/drm/i915/i915_params.c         |    9 +
>  drivers/gpu/drm/i915/i915_reg.h            |   92 ++-
>  drivers/gpu/drm/i915/intel_guc.h           |  184 ++++++
>  drivers/gpu/drm/i915/intel_guc_api.h       |  227 ++++++++
>  drivers/gpu/drm/i915/intel_guc_loader.c    |  498 ++++++++++++++++
>  drivers/gpu/drm/i915/intel_lrc.c           |  128 ++--
>  drivers/gpu/drm/i915/intel_lrc.h           |    8 +
>  drivers/gpu/drm/i915/intel_uc_loader.c     |  312 ++++++++++
>  drivers/gpu/drm/i915/intel_uc_loader.h     |   82 +++
>  18 files changed, 2607 insertions(+), 101 deletions(-)
>  create mode 100644 drivers/gpu/drm/i915/i915_guc_submission.c
>  create mode 100644 drivers/gpu/drm/i915/intel_guc.h
>  create mode 100644 drivers/gpu/drm/i915/intel_guc_api.h
>  create mode 100644 drivers/gpu/drm/i915/intel_guc_loader.c
>  create mode 100644 drivers/gpu/drm/i915/intel_uc_loader.c
>  create mode 100644 drivers/gpu/drm/i915/intel_uc_loader.h
> 
> -- 
> 1.7.9.5
> 
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> Intel-gfx@lists.freedesktop.org
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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