| Message ID | 20230123171556.3322164-1-lucas.demarchi@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2.1] drm/i915: Add _PICK_EVEN_2RANGES() | expand |
> -----Original Message----- > From: De Marchi, Lucas <lucas.demarchi@intel.com> > Sent: Monday, January 23, 2023 9:16 AM > To: intel-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org > Cc: Srivatsa, Anusha <anusha.srivatsa@intel.com>; Jani Nikula > <jani.nikula@linux.intel.com>; De Marchi, Lucas <lucas.demarchi@intel.com> > 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@intel.com> Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com> > --- > 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
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. *
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@intel.com> --- drivers/gpu/drm/i915/i915_reg_defs.h | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)