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Message-ID: <5e039cd8fe415dd7ab3169948c08a5311db9fb9a.1715024007.git.christophe.jaillet@wanadoo.fr>
Date: Mon, 6 May 2024 21:33:33 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Mark Brown <broonie@...nel.org>
Cc: linux-kernel@...r.kernel.org,
kernel-janitors@...r.kernel.org,
Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH v1] regmap: Reorder fields in 'struct regmap_config' to save some memory
On x86_64 and allmodconfig, this shrinks the size of 'struct regmap_config'
from 328 to 312 bytes.
This is usually a win, because this structure is used as a static global
variable.
When moving the kerneldoc fields, I've tried to keep the layout as
consistent as possible, which is not really easy!
Before:
/* size: 328, cachelines: 6, members: 55 */
/* sum members: 296, holes: 6, sum holes: 25 */
/* padding: 7 */
/* last cacheline: 8 bytes */
After:
/* size: 312, cachelines: 5, members: 55 */
/* sum members: 296, holes: 5, sum holes: 16 */
/* last cacheline: 56 bytes */
For the records, this is also widely used:
$git grep static.*regmap_config | wc -l
1327
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
Built-tested only on several dozens of modified files.
Example of size reduction on drivers/clk/clk-si544.o (randomly chosen)
Before:
text data bss dec hex filename
9917 700 16 10633 2989 drivers/clk/clk-si544.o
After:
text data bss dec hex filename
9885 700 16 10601 2969 drivers/clk/clk-si544.o
---
include/linux/regmap.h | 62 +++++++++++++++++++++---------------------
1 file changed, 31 insertions(+), 31 deletions(-)
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index d470303b1bbb..a6bc2980a98b 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -297,15 +297,6 @@ typedef void (*regmap_unlock)(void *);
* performed on such table (a register is no increment
* readable if it belongs to one of the ranges specified
* by rd_noinc_table).
- * @disable_locking: This regmap is either protected by external means or
- * is guaranteed not to be accessed from multiple threads.
- * Don't use any locking mechanisms.
- * @lock: Optional lock callback (overrides regmap's default lock
- * function, based on spinlock or mutex).
- * @unlock: As above for unlocking.
- * @lock_arg: this field is passed as the only argument of lock/unlock
- * functions (ignored in case regular lock/unlock functions
- * are not overridden).
* @reg_read: Optional callback that if filled will be used to perform
* all the reads from the registers. Should only be provided for
* devices whose read operation cannot be represented as a simple
@@ -323,6 +314,7 @@ typedef void (*regmap_unlock)(void *);
* @write: Same as above for writing.
* @max_raw_read: Max raw read size that can be used on the device.
* @max_raw_write: Max raw write size that can be used on the device.
+ * @can_sleep: Optional, specifies whether regmap operations can sleep.
* @fast_io: Register IO is fast. Use a spinlock instead of a mutex
* to perform locking. This field is ignored if custom lock/unlock
* functions are used (see fields lock/unlock of struct regmap_config).
@@ -331,6 +323,15 @@ typedef void (*regmap_unlock)(void *);
* Use it only for "no-bus" cases.
* @io_port: Support IO port accessors. Makes sense only when MMIO vs. IO port
* access can be distinguished.
+ * @disable_locking: This regmap is either protected by external means or
+ * is guaranteed not to be accessed from multiple threads.
+ * Don't use any locking mechanisms.
+ * @lock: Optional lock callback (overrides regmap's default lock
+ * function, based on spinlock or mutex).
+ * @unlock: As above for unlocking.
+ * @lock_arg: This field is passed as the only argument of lock/unlock
+ * functions (ignored in case regular lock/unlock functions
+ * are not overridden).
* @max_register: Optional, specifies the maximum valid register address.
* @max_register_is_0: Optional, specifies that zero value in @max_register
* should be taken into account. This is a workaround to
@@ -373,21 +374,20 @@ typedef void (*regmap_unlock)(void *);
* @reg_defaults_raw: Power on reset values for registers (for use with
* register cache support).
* @num_reg_defaults_raw: Number of elements in reg_defaults_raw.
- * @reg_format_endian: Endianness for formatted register addresses. If this is
- * DEFAULT, the @reg_format_endian_default value from the
- * regmap bus is used.
- * @val_format_endian: Endianness for formatted register values. If this is
- * DEFAULT, the @reg_format_endian_default value from the
- * regmap bus is used.
- *
- * @ranges: Array of configuration entries for virtual address ranges.
- * @num_ranges: Number of range configuration entries.
* @use_hwlock: Indicate if a hardware spinlock should be used.
* @use_raw_spinlock: Indicate if a raw spinlock should be used.
* @hwlock_id: Specify the hardware spinlock id.
* @hwlock_mode: The hardware spinlock mode, should be HWLOCK_IRQSTATE,
* HWLOCK_IRQ or 0.
- * @can_sleep: Optional, specifies whether regmap operations can sleep.
+ * @reg_format_endian: Endianness for formatted register addresses. If this is
+ * DEFAULT, the @reg_format_endian_default value from the
+ * regmap bus is used.
+ * @val_format_endian: Endianness for formatted register values. If this is
+ * DEFAULT, the @reg_format_endian_default value from the
+ * regmap bus is used.
+ *
+ * @ranges: Array of configuration entries for virtual address ranges.
+ * @num_ranges: Number of range configuration entries.
*/
struct regmap_config {
const char *name;
@@ -406,11 +406,6 @@ struct regmap_config {
bool (*writeable_noinc_reg)(struct device *dev, unsigned int reg);
bool (*readable_noinc_reg)(struct device *dev, unsigned int reg);
- bool disable_locking;
- regmap_lock lock;
- regmap_unlock unlock;
- void *lock_arg;
-
int (*reg_read)(void *context, unsigned int reg, unsigned int *val);
int (*reg_write)(void *context, unsigned int reg, unsigned int val);
int (*reg_update_bits)(void *context, unsigned int reg,
@@ -422,9 +417,16 @@ struct regmap_config {
size_t max_raw_read;
size_t max_raw_write;
+ bool can_sleep;
+
bool fast_io;
bool io_port;
+ bool disable_locking;
+ regmap_lock lock;
+ regmap_unlock unlock;
+ void *lock_arg;
+
unsigned int max_register;
bool max_register_is_0;
const struct regmap_access_table *wr_table;
@@ -448,18 +450,16 @@ struct regmap_config {
bool use_relaxed_mmio;
bool can_multi_write;
- enum regmap_endian reg_format_endian;
- enum regmap_endian val_format_endian;
-
- const struct regmap_range_cfg *ranges;
- unsigned int num_ranges;
-
bool use_hwlock;
bool use_raw_spinlock;
unsigned int hwlock_id;
unsigned int hwlock_mode;
- bool can_sleep;
+ enum regmap_endian reg_format_endian;
+ enum regmap_endian val_format_endian;
+
+ const struct regmap_range_cfg *ranges;
+ unsigned int num_ranges;
};
/**
--
2.45.0
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