On Fri, Oct 17, 2025 at 05:18:21PM +0530, Naladala Ramanaidu wrote: > In cases where the requested minimum CDCLK exceeds all available > values for the current reference clock, the CDCLK selection logic > previously returned 0. This could result coverity division or > modulo by zero issue. > > This change introduces a fallback mechanism that selects the last > valid CDCLK value associated with the current reference clock. A > warning is logged to indicate that the minimum requirement could > not be satisfied, and a safe fallback value is used instead. > > Fixes: Coverity CID 2628056 > > Signed-off-by: Naladala Ramanaidu <[email protected]> > --- > drivers/gpu/drm/i915/display/intel_cdclk.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c > b/drivers/gpu/drm/i915/display/intel_cdclk.c > index e92e7fd9fd13..a90b602a40c4 100644 > --- a/drivers/gpu/drm/i915/display/intel_cdclk.c > +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c > @@ -1551,17 +1551,21 @@ static int cdclk_divider(int cdclk, int vco, u16 > waveform) > static int bxt_calc_cdclk(struct intel_display *display, int min_cdclk) > { > const struct intel_cdclk_vals *table = display->cdclk.table; > - int i; > + int i, last_valid_cdclk = 0; > > - for (i = 0; table[i].refclk; i++) > + for (i = 0; table[i].refclk; i++) { > if (table[i].refclk == display->cdclk.hw.ref && > table[i].cdclk >= min_cdclk) > return table[i].cdclk; > > + if (table[i].refclk == display->cdclk.hw.ref) > + last_valid_cdclk = table[i].cdclk; > + } > + > drm_WARN(display->drm, 1, > - "Cannot satisfy minimum cdclk %d with refclk %u\n", > - min_cdclk, display->cdclk.hw.ref); > - return 0;
Will never happen because we never pass in a min_cdclk that high into this function. At some point I was thinking of determining the max cdclk via 'calc_cdclk(INT_MAX)' to get rid of some of the magic numbers in intel_update_max_cdclk(). But I think in some cases the table will contain values >max_cdclk anyway, so that probably is not going to fly anyway. So without that I don't think we really need this much complexity and you could just do: - return 0; + return display->cdclk.max_cdclk_freq; > + "Cannot satisfy minimum cdclk %d with refclk %u, falling back > to %d\n", > + min_cdclk, display->cdclk.hw.ref, last_valid_cdclk); > + return last_valid_cdclk; > } > > static int bxt_calc_cdclk_pll_vco(struct intel_display *display, int cdclk) > -- > 2.43.0 -- Ville Syrjälä Intel
