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Dhinakaran Pandiyan authored
We store DP link rates as link clock frequencies in kHz, just like all other clock values. But, DP link rates in the DP Spec. are expressed in Gbps/lane, which seems to have led to some confusion. E.g., for HBR2 Max. data rate = 5.4 Gbps/lane x 4 lane x 8/10 x 1/8 = 2160000 kBps where, 8/10 is for channel encoding and 1/8 is for bit to Byte conversion Using link clock frequency, like we do Max. data rate = 540000 kHz * 4 lanes = 2160000 kSymbols/s Because, each symbol has 8 bit of data, this is 2160000 kBps and there is no need to account for channel encoding here. But, currently we do 540000 kHz * 4 lanes * (8/10) = 1728000 kBps Similarly, while computing the required link bandwidth for a mode, there is a mysterious 1/10 term. This should simply be pixel_clock kHz * (bpp/8) to give the final result in kBps v2: Changed to DIV_ROUND_UP() and comment changes (Ville) Signed-off-by:
Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1479160220-17794-1-git-send-email-dhinakaran.pandiyan@intel.comSigned-off-by:
Ville Syrjälä <ville.syrjala@linux.intel.com>
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