diff options
| author |   Chris Wilson <chris@chris-wilson.co.uk> | 2010-12-04 01:01:29 +0000 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2010-12-03 23:51:02 +0000 |
| commit | 22ed1113a9adda6e193c329119a384362da01289 (patch) | |
| tree | f9c8c2132c539f7fe3230c75aab11a8f927b4af6 /drivers | |
| parent | drm/i915: Clean conflicting modesetting registers upon init (diff) | |
| download | linux-dev-22ed1113a9adda6e193c329119a384362da01289.tar.xz linux-dev-22ed1113a9adda6e193c329119a384362da01289.zip | |
drm/i915: Death to the unnecessary 64bit divide
Use the hardware DDA to calculate the ratio with as much accuracy as is
possible.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_display.c | 18 |
1 files changed, 5 insertions, 13 deletions
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index e5badadbdcd2..fac118b2df7d 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -2714,27 +2714,19 @@ fdi_reduce_ratio(u32 *num, u32 *den) } } -#define DATA_N 0x800000 -#define LINK_N 0x80000 - static void ironlake_compute_m_n(int bits_per_pixel, int nlanes, int pixel_clock, int link_clock, struct fdi_m_n *m_n) { - u64 temp; - m_n->tu = 64; /* default size */ - temp = (u64) DATA_N * pixel_clock; - temp = div_u64(temp, link_clock); - m_n->gmch_m = div_u64(temp * bits_per_pixel, nlanes); - m_n->gmch_m >>= 3; /* convert to bytes_per_pixel */ - m_n->gmch_n = DATA_N; + /* BUG_ON(pixel_clock > INT_MAX / 36); */ + m_n->gmch_m = bits_per_pixel * pixel_clock; + m_n->gmch_n = link_clock * nlanes * 8; fdi_reduce_ratio(&m_n->gmch_m, &m_n->gmch_n); - temp = (u64) LINK_N * pixel_clock; - m_n->link_m = div_u64(temp, link_clock); - m_n->link_n = LINK_N; + m_n->link_m = pixel_clock; + m_n->link_n = link_clock; fdi_reduce_ratio(&m_n->link_m, &m_n->link_n); } |