| Message ID | 1380666758-28963-1-git-send-email-benjamin.widawsky@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 1 Oct 2013 15:32:38 -0700 Ben Widawsky <benjamin.widawsky@intel.com> wrote: > 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 <jbarnes@virtuousgeek.org> > CC: Chris Wilson <chris@chris-wilson.co.uk> > Signed-off-by: Ben Widawsky <ben@bwidawsk.net> > --- > 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 { Seems like the second mult_frac should be 5,4 rather than 4,3, to match the original calculation?
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 {
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 <jbarnes@virtuousgeek.org> CC: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Ben Widawsky <ben@bwidawsk.net> --- drivers/gpu/drm/i915/intel_pm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)