[Intel-gfx] [PATCH 1/2] drm/i915/lrc: Clarify the format of the context image
Michel Thierry
michel.thierry at intel.com
Wed Jul 12 21:27:26 UTC 2017
On 7/12/2017 12:45 PM, Chris Wilson wrote:
> Quoting Michel Thierry (2017-07-12 20:30:31)
>> Not only the context image consist of two parts (the PPHWSP, and the
>> logical context state), but we also allocate a header at the start of
>> for sharing data with GuC. Thus every lrc looks like this:
>>
>> | [guc] | [hwsp] [logical state] |
>> |<- our header ->|<- context image ->|
>>
>> So far, we have oversimplified whenever we use each of these parts of the
>> context, just because the GuC header happens to be in page 0, and the
>> (PP)HWSP is in page 1. But this had led to using the same define for more
>> than one meaning (as a page index in the lrc and as 1 page).
>>
>> This patch adds defines for the GuC shared page, the PPHWSP page and the
>> start of the logical state. It also updated the places where the old
>> define was being used. Since we are not changing the size (or format) of
>> the context, there are no functional changes.
>>
>> Suggested-by: Chris Wilson <chris at chris-wilson.co.uk>
>> Signed-off-by: Michel Thierry <michel.thierry at intel.com>
>> Cc: Chris Wilson <chris at chris-wilson.co.uk>
>> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
>> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
>> Cc: Oscar Mateo <oscar.mateo at intel.com>
>> Cc: intel-gvt-dev at lists.freedesktop.org
>> ---
>> drivers/gpu/drm/i915/gvt/scheduler.c | 4 ++--
>> drivers/gpu/drm/i915/i915_guc_submission.c | 4 ++--
>> drivers/gpu/drm/i915/intel_lrc.c | 11 +++++++----
>> drivers/gpu/drm/i915/intel_lrc.h | 25 ++++++++++++++++++++++---
>> 4 files changed, 33 insertions(+), 11 deletions(-)
>>
...
>> @@ -1695,7 +1695,7 @@ logical_ring_default_irqs(struct intel_engine_cs *engine)
>> static int
>> lrc_setup_hws(struct intel_engine_cs *engine, struct i915_vma *vma)
>> {
>> - const int hws_offset = LRC_PPHWSP_PN * PAGE_SIZE;
>> + const int hws_offset = LRC_HEADER_PAGES * PAGE_SIZE;
>
> This should be PPHWSP_PN since we explicitly want the pointer tot he
> pphwsp.
>Oh right, this was the only place where it was really correct.
I was about to resend it with this change, but then realised it just
means the lrc_setup_hws chunk of the patch disappears... let me know if
I should still resend it.
Thanks,
>> void *hws;
>>
>> /* The HWSP is part of the default context object in LRC mode. */
>> @@ -2015,8 +2015,11 @@ static int execlists_context_deferred_alloc(struct i915_gem_context *ctx,
>>
>> context_size = round_up(engine->context_size, I915_GTT_PAGE_SIZE);
>>
>> - /* One extra page as the sharing data between driver and GuC */
>> - context_size += PAGE_SIZE * LRC_PPHWSP_PN;
>> + /*
>> + * Before the actual start of the context image, we insert a few pages
>> + * for our own use and for sharing with the GuC.
>> + */
>> + context_size += LRC_HEADER_PAGES * PAGE_SIZE;
>
> Good riddance, that LRC_PPHWSP_PN has left me quite confused for some
> time.
>
> With the change to lrc_setup_hws,
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> -Chris
>
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