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drm/i915: Avoid div-by-zero in clock calculation funcs 

Check that the N and P dividers don't cause a divide by zero.

This shouldn't happen under normal circumstances, but can
happen eg. under simulation.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Ville Syrjälä 2013-12-02 19:00:45 +02:00 committed by Daniel Vetter
parent 7e11f9f4ca
commit ed5ca77ed7
1 changed files with 6 additions and 0 deletions
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6
drivers/gpu/drm/i915/intel_display.c
View File

@ -329,6 +329,8 @@ static void vlv_clock(int refclk, intel_clock_t *clock)
{
clock->m = clock->m1 * clock->m2;
clock->p = clock->p1 * clock->p2;
if (WARN_ON(clock->n == 0 || clock->p == 0))
return;
clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
}
@ -430,6 +432,8 @@ static void pineview_clock(int refclk, intel_clock_t *clock)
{
clock->m = clock->m2 + 2;
clock->p = clock->p1 * clock->p2;
if (WARN_ON(clock->n == 0 || clock->p == 0))
return;
clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
}
@ -443,6 +447,8 @@ static void i9xx_clock(int refclk, intel_clock_t *clock)
{
clock->m = i9xx_dpll_compute_m(clock);
clock->p = clock->p1 * clock->p2;
if (WARN_ON(clock->n + 2 == 0 || clock->p == 0))
return;
clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n + 2);
clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
}