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| author | Matt Roper <matthew.d.roper@intel.com> | 2015-12-03 11:37:40 -0800 |
|---|---|---|
| committer | Maarten Lankhorst <maarten.lankhorst@linux.intel.com> | 2016-01-06 11:35:29 +0100 |
| commit | 151268821e6f08956b28b6ff90fae187a5b230b8 (patch) | |
| tree | f337a00ef44c248b8d700bf28c8dea1c4846718e /drivers/gpu/drm | |
| parent | ee91a15972cc70efa4d17b4bbdb61ff314528110 (diff) | |
| download | lwn-151268821e6f08956b28b6ff90fae187a5b230b8.tar.gz lwn-151268821e6f08956b28b6ff90fae187a5b230b8.zip | |
drm/i915: Add extra paranoia to ILK watermark calculations
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@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1449171462-30763-6-git-send-email-matthew.d.roper@intel.com
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Diffstat (limited to 'drivers/gpu/drm')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_pm.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 0f22d11937b4..f9cbd2e81f54 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; } |