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drm/i915/doc: Document where to implement register workarounds

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Extend the existing documentation in gt/intel_workarounds.c to make it
clear which functions register workarounds should be implemented in
according to their types.

Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230118155249.41551-2-gustavo.sousa@intel.com
This commit is contained in:
Gustavo Sousa 2023-01-18 12:52:48 -03:00 • committed by Rodrigo Vivi
parent ca54a9a32d
commit 0c3064cf33
1 changed files with 16 additions and 0 deletions
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16
drivers/gpu/drm/i915/gt/intel_workarounds.c
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@ -30,6 +30,9 @@
* creation to have a "primed golden context", i.e. a context image that
* already contains the changes needed to all the registers.
*
* Context workarounds should be implemented in the *_ctx_workarounds_init()
* variants respective to the targeted platforms.
*
* - Engine workarounds: the list of these WAs is applied whenever the specific
* engine is reset. It's also possible that a set of engine classes share a
* common power domain and they are reset together. This happens on some
@ -42,15 +45,28 @@
* saves/restores their values before/after the reset takes place. See
* ``drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c`` for reference.
*
* Workarounds for registers specific to RCS and CCS should be implemented in
* rcs_engine_wa_init() and ccs_engine_wa_init(), respectively; those for
* registers belonging to BCS, VCS or VECS should be implemented in
* xcs_engine_wa_init(). Workarounds for registers not belonging to a specific
* engine's MMIO range but that are part of of the common RCS/CCS reset domain
* should be implemented in general_render_compute_wa_init().
*
* - GT workarounds: the list of these WAs is applied whenever these registers
* revert to their default values: on GPU reset, suspend/resume [1]_, etc.
*
* GT workarounds should be implemented in the *_gt_workarounds_init()
* variants respective to the targeted platforms.
*
* - Register whitelist: some workarounds need to be implemented in userspace,
* but need to touch privileged registers. The whitelist in the kernel
* instructs the hardware to allow the access to happen. From the kernel side,
* this is just a special case of a MMIO workaround (as we write the list of
* these to/be-whitelisted registers to some special HW registers).
*
* Register whitelisting should be done in the *_whitelist_build() variants
* respective to the targeted platforms.
*
* - Workaround batchbuffers: buffers that get executed automatically by the
* hardware on every HW context restore. These buffers are created and
* programmed in the default context so the hardware always go through those