Commit dff457d7 authored Sep 05, 2017 by David Weinehall Committed by Chris Wilson Sep 25, 2017

drm/i915: Speed up DMC firmware loading



Currently we're doing:

1. acquire lock
2. write word to hardware
3. release lock
4. repeat from 1

to load the DMC firmware. Due to the cost of acquiring/releasing a lock,
and the size of the DMC firmware, this slows down DMC loading a lot.

This patch simply acquires the lock, writes the entire firmware,
then releases the lock.  Testing shows resume speedups
in the order of 10ms on platforms with DMC firmware (GEN9+).

v2: Per feedback from Chris & Ville there's no need to do the whole
    forcewake dance, so lose that bit (Chris, Ville)

v3: Actually send the new version of the patch...

v4: Don't acquire the uncore lock. Disable preempt. (Chris)

Signed-off-by: David Weinehall <david.weinehall@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170905131050.11655-1-david.weinehall@linux.intel.com


Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

parent 3bc31a7f

drivers/gpu/drm/i915/intel_csr.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -252,8 +252,14 @@ void intel_csr_load_program(struct drm_i915_private *dev_priv)
		}

		fw_size = dev_priv->csr.dmc_fw_size;
		assert_rpm_wakelock_held(dev_priv);

		preempt_disable();

		for (i = 0; i < fw_size; i++)
		I915_WRITE(CSR_PROGRAM(i), payload[i]);
		I915_WRITE_FW(CSR_PROGRAM(i), payload[i]);

		preempt_enable();

		for (i = 0; i < dev_priv->csr.mmio_count; i++) {
		I915_WRITE(dev_priv->csr.mmioaddr[i],