Our low-level watermark calculation functions don't get called when the CRTC is disabled or the relevant plane is invisible, so they should never see a zero htotal or zero bpp. However add some checks to ensure this is true so that we don't wind up dividing by zero if we make a mistake elsewhere in the driver (which the atomic watermark series has revealed we might be). References: http://lists.freedesktop.org/archives/intel-gfx/2015-October/077370.html Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx> --- drivers/gpu/drm/i915/intel_pm.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 9a31480..1972ec5 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -1672,6 +1672,9 @@ uint32_t ilk_pipe_pixel_rate(const struct intel_crtc_state *pipe_config) if (pipe_h < pfit_h) pipe_h = pfit_h; + if (WARN_ON(!pfit_w || !pfit_h)) + return pixel_rate; + pixel_rate = div_u64((uint64_t) pixel_rate * pipe_w * pipe_h, pfit_w * pfit_h); } @@ -1703,6 +1706,8 @@ static uint32_t ilk_wm_method2(uint32_t pixel_rate, uint32_t pipe_htotal, if (WARN(latency == 0, "Latency value missing\n")) return UINT_MAX; + if (WARN_ON(!pipe_htotal)) + return UINT_MAX; ret = (latency * pixel_rate) / (pipe_htotal * 10000); ret = (ret + 1) * horiz_pixels * bytes_per_pixel; @@ -1713,6 +1718,17 @@ static uint32_t ilk_wm_method2(uint32_t pixel_rate, uint32_t pipe_htotal, static uint32_t ilk_wm_fbc(uint32_t pri_val, uint32_t horiz_pixels, uint8_t bytes_per_pixel) { + /* + * Neither of these should be possible since this function shouldn't be + * called if the CRTC is off or the plane is invisible. But let's be + * extra paranoid to avoid a potential divide-by-zero if we screw up + * elsewhere in the driver. + */ + if (WARN_ON(!bytes_per_pixel)) + return 0; + if (WARN_ON(!horiz_pixels)) + return 0; + return DIV_ROUND_UP(pri_val * 64, horiz_pixels * bytes_per_pixel) + 2; } -- 2.1.4 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
