• Matt Roper's avatar
    drm/i915: Use literal representation of cdclk tables · 736da811
    Matt Roper authored
    The bspec lays out legal cdclk frequencies, PLL ratios, and CD2X
    dividers in an easy-to-read table for most recent platforms.  We've been
    translating the data from that table into platform-specific code logic,
    but it's easy to overlook an area we need to update when adding new
    cdclk values or enabling new platforms.  Let's just add a form of the
    bspec table to the code and then adjust our functions to pull what they
    need directly out of the table.
    
    v2: Fix comparison when finding best cdclk.
    
    v3: Another logic fix for calc_cdclk.
    
    v4:
     - Use named initializers for cdclk tables. (Ville)
     - Include refclk as a field in the table instead of adding all three
       ratios for each entry. (Ville)
     - Terminate tables with an empty entry to avoid needing to store the
       table size. (Ville)
     - Don't try so hard to return reasonable values from our lookup
       functions if we get impossible inputs; just WARN and return 0.
       (Ville)
     - Keep a bxt_ prefix on the lookup functions since they're still only
       used on bxt+ for now.  We can rename them later if we extend this
       table-based approach back to older platforms.  (Ville)
    
    v5:
     - Fix cnl table's ratios for 24mhz refclk. (Ville)
     - Don't miss the named initializers on the cnl table. (Ville)
     - Represent refclk in table as u16 rather than u32. (Ville)
    
    Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
    Signed-off-by: default avatarMatt Roper <matthew.d.roper@intel.com>
    Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
    Link: https://patchwork.freedesktop.org/patch/msgid/20190910161506.7158-1-matthew.d.roper@intel.com
    736da811
intel_cdclk.h 1.74 KB