On Wed, 14 Oct 2015, Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote: > On Wed, 14 Oct 2015, Dave Gordon <david.s.gordon@xxxxxxxxx> wrote: >> On 17/09/15 14:20, Damien Lespiau wrote: >>> Not the first time! not the last time? >>> >>> There is a possibility to use gcc 5's -Wbool-compare to try and compare >>> (reg) in those macros to a constant and gcc will warn that the >>> comparison between a boolean expression and a constant is always either >>> true or false. Maybe. >> >> Since boolean true (1) cannot be a valid argument to this macro, it >> could contain a compile-time check that the parameter is not 1; if >> boolean false (0) happens not to be a valid register address (BSpec says >> MMIO 0 is reserved) the macro could check that the argument is neither >> of these values, and the compiler might then detect that all possible >> paths lead to a compile-time error. Something like this? > > The past errors have also been of the form > > if (I915_READ(SOME_REG(pipe) & MASK) == val) > > which isn't caught by your check. See [1]. > > > BR, > Jani. > > > [1] http://mid.gmane.org/1442595836-23981-1-git-send-email-ville.syrjala@xxxxxxxxxxxxxxx > > > > > >> >> #define I915_READ(reg) \ >> ({ \ >> if (__builtin_constant_p(reg)) { \ Also, what Damien fixed wouldn't have been caught because "BXT_PORT_PCS_DW12_LN23(port) != hw_state->pcsdw12" is not a builtin constant. Daniel, I don't think this is interim solution material, sorry. BR, Jani. >> BUILD_BUG_ON((reg) == false); \ >> BUILD_BUG_ON((reg) == true); \ >> } \ >> dev_priv->uncore.funcs.mmio_readl(dev_priv, (reg), true); \ >> }) >> >> Interestingly, that reported three errors, all in intel_dsi.c where the >> port-selection macros use 0s to fill in dummy elements when less than 3 >> ports are being used. >> >> In function ‘intel_dsi_get_hw_state’ >> In function ‘intel_dsi_port_disable’ >> In function ‘intel_dsi_port_enable’ >> >> Other than that, there weren't any cases where a bool constant was being >> passed to this specific macro (as of today). >> >> .Dave. >> >>> Cc: Imre Deak <imre.deak@xxxxxxxxx> >>> Signed-off-by: Damien Lespiau <damien.lespiau@xxxxxxxxx> >>> --- >>> drivers/gpu/drm/i915/intel_ddi.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c >>> index 4823184..5b600bf 100644 >>> --- a/drivers/gpu/drm/i915/intel_ddi.c >>> +++ b/drivers/gpu/drm/i915/intel_ddi.c >>> @@ -2882,7 +2882,7 @@ static bool bxt_ddi_pll_get_hw_state(struct drm_i915_private *dev_priv, >>> * here just read out lanes 0/1 and output a note if lanes 2/3 differ. >>> */ >>> hw_state->pcsdw12 = I915_READ(BXT_PORT_PCS_DW12_LN01(port)); >>> - if (I915_READ(BXT_PORT_PCS_DW12_LN23(port) != hw_state->pcsdw12)) >>> + if (I915_READ(BXT_PORT_PCS_DW12_LN23(port)) != hw_state->pcsdw12) >>> DRM_DEBUG_DRIVER("lane stagger config different for lane 01 (%08x) and 23 (%08x)\n", >>> hw_state->pcsdw12, >>> I915_READ(BXT_PORT_PCS_DW12_LN23(port))); >> >> >> _______________________________________________ >> Intel-gfx mailing list >> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx >> http://lists.freedesktop.org/mailman/listinfo/intel-gfx > > -- > Jani Nikula, Intel Open Source Technology Center -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
