> -----Original Message----- > From: De Marchi, Lucas <lucas.demarchi@xxxxxxxxx> > Sent: Monday, January 23, 2023 9:16 AM > To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx > Cc: Srivatsa, Anusha <anusha.srivatsa@xxxxxxxxx>; Jani Nikula > <jani.nikula@xxxxxxxxxxxxxxx>; De Marchi, Lucas <lucas.demarchi@xxxxxxxxx> > Subject: [PATCH v2.1] drm/i915: Add _PICK_EVEN_2RANGES() > > It's a constant pattern in the driver to need to use 2 ranges of MMIOs based on > port, phy, pll, etc. When that happens, instead of using _PICK_EVEN(), _PICK() > needs to be used. Using _PICK() is discouraged due to some reasons like: > > 1) It increases the code size since the array is declared > in each call site > 2) Developers need to be careful not to incur an > out-of-bounds array access > 3) Developers need to be careful that the indexes match the > table. For that it may be that the table needs to contain > holes, making (1) even worse. > > Add a variant of _PICK_EVEN() that works with 2 ranges and selects which one > to use depending on the index value. > > v2: Fix the address expansion in the example (Anusha) > > Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx> Reviewed-by: Anusha Srivatsa <anusha.srivatsa@xxxxxxxxx> > --- > drivers/gpu/drm/i915/i915_reg_defs.h | 28 ++++++++++++++++++++++++++++ > 1 file changed, 28 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_reg_defs.h > b/drivers/gpu/drm/i915/i915_reg_defs.h > index be43580a6979..bab6a9ec2ddd 100644 > --- a/drivers/gpu/drm/i915/i915_reg_defs.h > +++ b/drivers/gpu/drm/i915/i915_reg_defs.h > @@ -119,6 +119,34 @@ > */ > #define _PICK_EVEN(__index, __a, __b) ((__a) + (__index) * ((__b) - (__a))) > > +/* > + * Like _PICK_EVEN(), but supports 2 ranges of evenly spaced address offsets. > + * The first range is used for indexes below @__c_index, and the second > + * range is used for anything above it. Example:: > + * > + * #define _FOO_A 0xf000 > + * #define _FOO_B 0xf004 > + * #define _FOO_C 0xf008 > + * #define _SUPER_FOO_A 0xa000 > + * #define _SUPER_FOO_B 0xa100 > + * #define FOO(x) _MMIO(_PICK_EVEN_RANGES(x, 3, > \ > + * _FOO_A, _FOO_B, > \ > + * _SUPER_FOO_A, _SUPER_FOO_B)) > + * > + * This expands to: > + * 0: 0xf000, > + * 1: 0xf004, > + * 2: 0xf008, > + * 3: 0xa000, > + * 4: 0xa100, > + * 5: 0xa200, > + * ... > + */ > +#define _PICK_EVEN_2RANGES(__index, __c_index, __a, __b, __c, __d) > \ > + (BUILD_BUG_ON_ZERO(!__is_constexpr(__c_index)) + > \ > + ((__index) < (__c_index) ? _PICK_EVEN(__index, __a, __b) : > \ > + _PICK_EVEN((__index) - (__c_index), __c, > __d))) > + > /* > * Given the arbitrary numbers in varargs, pick the 0-based __index'th number. > * > -- > 2.39.0
