commit: 22ed1113a9adda6e193c329119a384362da01289 From: Chris Wilson <[email protected]> Date: Sat, 4 Dec 2010 01:01:29 +0000 Subject: [PATCH] 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 <[email protected]> Cc: [email protected] --- 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 e5badad..fac118b 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); } _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
