Why is this patch deemed for -stable? What bug does it solve?
confused, greg k-h > 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 _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
