On Sat, 21 Jan 2023, Lucas De Marchi <lucas.demarchi@xxxxxxxxx> wrote: > On Fri, Jan 20, 2023 at 10:14:19PM -0800, Anusha Srivatsa wrote: >> >> >>> -----Original Message----- >>> From: Intel-gfx <intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Lucas >>> De Marchi >>> Sent: Friday, January 20, 2023 11:35 AM >>> To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx >>> Cc: De Marchi, Lucas <lucas.demarchi@xxxxxxxxx>; dri- >>> devel@xxxxxxxxxxxxxxxxxxxxx >>> Subject: [Intel-gfx] [PATCH v2 1/8] 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. >>> >>> Signed-off-by: Lucas De Marchi <lucas.demarchi@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..b7ec87464d69 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: 0xa100, >>You mean 3:0xa000 > > doesn't really matter. This is an example of register addresses. They > don't need to start from 0, it's whatever the hw gives us. I think the point is that the example is inconsistent between _SUPER_FOO_A and "3: 0xa100". BR, Jani. > > Lucas De Marchi > >> >>> + * 4: 0xa200, >>4:0xa100 >> >>> + * 5: 0xa300, >>5:0xa200 >> >>Anusha >>> + * ... >>> + */ >>> +#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 >> -- Jani Nikula, Intel Open Source Graphics Center
