From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Widawsky Subject: [PATCH] [v2] drm/i915: Clean up the ring scaling calculations Date: Tue, 1 Oct 2013 15:32:38 -0700 Message-ID: <1380666758-28963-1-git-send-email-benjamin.widawsky@intel.com> References: <1380657190-19261-1-git-send-email-benjamin.widawsky@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by gabe.freedesktop.org (Postfix) with ESMTP id 6D816E793D for ; Tue, 1 Oct 2013 15:32:40 -0700 (PDT) In-Reply-To: <1380657190-19261-1-git-send-email-benjamin.widawsky@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Intel GFX Cc: Ben Widawsky , Ben Widawsky List-Id: intel-gfx@lists.freedesktop.org This patch attempts to clean up the ring/IA scaling programming in the following ways. 1. Fix the comment about the DDR frequency. The math is 266MHz, not 133MHz. Formula was right, docs are wrong. 2. Mask the DCLK register since I don't know how it is defined on future platforms. 3. use mult_frac instead of magic math. This helps for future platform enabling. v2: Actually use the right patch. The v1 was a mix of things, none of which was right. Note that due to rounding, we actually get different values (slightly higher) for the effective ring frequency. CC: Jesse Barnes CC: Chris Wilson Signed-off-by: Ben Widawsky --- drivers/gpu/drm/i915/intel_pm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 698257c..cb0876b 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -3663,9 +3663,9 @@ void gen6_update_ring_freq(struct drm_device *dev) /* Convert from kHz to MHz */ max_ia_freq /= 1000; - min_ring_freq = I915_READ(MCHBAR_MIRROR_BASE_SNB + DCLK); - /* convert DDR frequency from units of 133.3MHz to bandwidth */ - min_ring_freq = (2 * 4 * min_ring_freq + 2) / 3; + min_ring_freq = I915_READ(MCHBAR_MIRROR_BASE_SNB + DCLK) & 0xf; + /* convert DDR frequency from units of 266.6MHz to bandwidth */ + min_ring_freq = mult_frac(min_ring_freq, 8, 3); /* * For each potential GPU frequency, load a ring frequency we'd like @@ -3678,7 +3678,7 @@ void gen6_update_ring_freq(struct drm_device *dev) unsigned int ia_freq = 0, ring_freq = 0; if (IS_HASWELL(dev)) { - ring_freq = (gpu_freq * 5 + 3) / 4; + ring_freq = mult_frac(gpu_freq, 4, 3); ring_freq = max(min_ring_freq, ring_freq); /* leave ia_freq as the default, chosen by cpufreq */ } else { -- 1.8.4