[Intel-gfx] [PATCH v2] drm/i915: Assert that the context-switch completion matches our context

[Tvrtko Ursulin]

On 23/01/2017 08:50, Chris Wilson wrote:
> When execlists signals the context completion, it also provides the
> context id for the status event. Assert that id matches the one we expect.
>
> v2: The upper dword of the context status is a duplicate of the upper
> dword from elsp submission (i.e. includes the group id as well as the
> context id). Include this check as well.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_lrc.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 432ee495dec2..963b1888d8a0 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -595,6 +595,12 @@ static void intel_lrc_irq_handler(unsigned long data)
>  			if (!(status & GEN8_CTX_STATUS_COMPLETED_MASK))
>  				continue;
>
> +			/* Check the context/desc id for this event matches */
> +			GEM_BUG_ON(((readl(buf + 2 * idx + 1) & (MAX_CONTEXT_HW_ID-1)) !=
> +				    port[0].request->ctx->hw_id));
> +			GEM_BUG_ON(readl(buf + 2 * idx + 1) !=
> +				   upper_32_bits(port[0].request->ctx->engine[engine->id].lrc_desc));
> +

Not sure that you need the first line since the lrc_desc includes the 
hw_id? Or perhaps you don't need the second one since lrc_desc is built 
from hw_id? :)

Regards,

Tvrtko


>  			GEM_BUG_ON(port[0].count == 0);
>  			if (--port[0].count == 0) {
>  				GEM_BUG_ON(status & GEN8_CTX_STATUS_PREEMPTED);
>