From: Lucas De Marchi lucas.demarchi@intel.com
[ Upstream commit 357513233d6456c9f99e34794897efd4ae907e83 ]
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) v3: Also rename macro to _PICK_EVEN_2RANGES() in the documentation and reword it to clarify what ranges are chosen based on the index (Jani)
Signed-off-by: Lucas De Marchi lucas.demarchi@intel.com Reviewed-by: Anusha Srivatsa anusha.srivatsa@intel.com Acked-by: Jani Nikula jani.nikula@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20230125182403.7526-1-lucas.de... Stable-dep-of: 214b09db6197 ("drm/msm: fix drm device leak on bind errors") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/i915/i915_reg_defs.h | 29 ++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_reg_defs.h b/drivers/gpu/drm/i915/i915_reg_defs.h index be43580a69793..983c5aa3045b3 100644 --- a/drivers/gpu/drm/i915/i915_reg_defs.h +++ b/drivers/gpu/drm/i915/i915_reg_defs.h @@ -119,6 +119,35 @@ */ #define _PICK_EVEN(__index, __a, __b) ((__a) + (__index) * ((__b) - (__a)))
+/* + * Like _PICK_EVEN(), but supports 2 ranges of evenly spaced address offsets. + * @__c_index corresponds to the index in which the second range starts to be + * used. Using math interval notation, the first range is used for indexes [ 0, + * @__c_index), while the second range is used for [ @__c_index, ... ). 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_2RANGES(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. *