Commit 8ea397fa authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/execlists: Process one CSB update at a time 



In the next patch, we will process the CSB events directly from the
submission path, rather than only after a CS interrupt. Hence, we will
no longer have the need for a loop until the has-interrupt bit is clear,
and in the meantime can remove that small optimisation.

v2: Tvrtko pointed out it was safer to unconditionally kick the tasklet
after each irq, when assuming that the tasklet is called for each irq.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180628201211.13837-4-chris@chris-wilson.co.uk
parent d8857d54

drivers/gpu/drm/i915/i915_irq.c

+4 −3
Original line number Diff line number Diff line
@@ -1497,9 +1497,10 @@ gen8_cs_irq_handler(struct intel_engine_cs *engine, u32 iir) 
	bool tasklet = false;



	if (iir & GT_CONTEXT_SWITCH_INTERRUPT) {

		if (READ_ONCE(engine->execlists.active))

			tasklet = !test_and_set_bit(ENGINE_IRQ_EXECLIST,

						    &engine->irq_posted);

		if (READ_ONCE(engine->execlists.active)) {

			set_bit(ENGINE_IRQ_EXECLIST, &engine->irq_posted);

			tasklet = true;

		}

	}



	if (iir & GT_RENDER_USER_INTERRUPT) {

drivers/gpu/drm/i915/intel_lrc.c

+137 −141
Original line number Diff line number Diff line
@@ -955,23 +955,20 @@ static void process_csb(struct intel_engine_cs *engine) 
	struct intel_engine_execlists * const execlists = &engine->execlists;

	struct execlist_port *port = execlists->port;

	struct drm_i915_private *i915 = engine->i915;

	bool fw = false;



	do {

	/* The HWSP contains a (cacheable) mirror of the CSB */

	const u32 *buf =

		&engine->status_page.page_addr[I915_HWS_CSB_BUF0_INDEX];

	unsigned int head, tail;

	bool fw = false;



	/* Clear before reading to catch new interrupts */

	clear_bit(ENGINE_IRQ_EXECLIST, &engine->irq_posted);

	smp_mb__after_atomic();



	if (unlikely(execlists->csb_use_mmio)) {

			if (!fw) {

		intel_uncore_forcewake_get(i915, execlists->fw_domains);

		fw = true;

			}



		buf = (u32 * __force)

			(i915->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_BUF_LO(engine, 0)));
@@ -1114,7 +1111,6 @@ static void process_csb(struct intel_engine_cs *engine) 
		writel(_MASKED_FIELD(GEN8_CSB_READ_PTR_MASK, head << 8),

		       i915->regs + i915_mmio_reg_offset(RING_CONTEXT_STATUS_PTR(engine)));

	}

	} while (test_bit(ENGINE_IRQ_EXECLIST, &engine->irq_posted));



	if (unlikely(fw))

		intel_uncore_forcewake_put(i915, execlists->fw_domains);

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