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.
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
