firmware: cirrus: cs_dsp: Avoid padding bytes in cs_dsp_coeff_ctl

Change the order of members in struct cs_dsp_coeff_ctl to avoid
the compiler having to insert alignment padding bytes. On a x86_64
build this saves 16 bytes per control.

- Pointers are collected to the top of the struct (with the exception of
  priv, as noted below), so that they are inherently aligned.
- The set and enable bitflags are placed together so they can be merged.
- priv is placed at the end of the struct - it is for use by the
  client so it is helpful to make it stand out, and since the compiler
  will always pad the struct size to an alignment multiple putting a
  pointer last won't introduce any more padding.
- struct cs_dsp_alg_region is placed at the end, right before priv, for
  the same reasoning as priv.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20220425095159.3044527-1-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/include/linux/firmware/cirrus/cs_dsp.h b/include/linux/firmware/cirrus/cs_dsp.h
index 38b4da3..3005570 100644 (file)
--- a/include/linux/firmware/cirrus/cs_dsp.h
+++ b/include/linux/firmware/cirrus/cs_dsp.h
@@ -68,36 +68,36 @@ struct cs_dsp_alg_region {
 
 /**
  * struct cs_dsp_coeff_ctl - Describes a coefficient control
+ * @list:              List node for internal use
+ * @dsp:               DSP instance associated with this control
+ * @cache:             Cached value of the control
  * @fw_name:           Name of the firmware
  * @subname:           Name of the control parsed from the WMFW
  * @subname_len:       Length of subname
- * @alg_region:                Logical region associated with this control
- * @dsp:               DSP instance associated with this control
- * @enabled:           Flag indicating whether control is enabled
- * @list:              List node for internal use
- * @cache:             Cached value of the control
  * @offset:            Offset of control within alg_region in words
  * @len:               Length of the cached value in bytes
- * @set:               Flag indicating the value has been written by the user
- * @flags:             Bitfield of WMFW_CTL_FLAG_ control flags defined in wmfw.h
  * @type:              One of the WMFW_CTL_TYPE_ control types defined in wmfw.h
+ * @flags:             Bitfield of WMFW_CTL_FLAG_ control flags defined in wmfw.h
+ * @set:               Flag indicating the value has been written by the user
+ * @enabled:           Flag indicating whether control is enabled
+ * @alg_region:                Logical region associated with this control
  * @priv:              For use by the client
  */
 struct cs_dsp_coeff_ctl {
+       struct list_head list;
+       struct cs_dsp *dsp;
+       void *cache;
        const char *fw_name;
        /* Subname is needed to match with firmware */
        const char *subname;
        unsigned int subname_len;
-       struct cs_dsp_alg_region alg_region;
-       struct cs_dsp *dsp;
-       unsigned int enabled:1;
-       struct list_head list;
-       void *cache;
        unsigned int offset;
        size_t len;
-       unsigned int set:1;
-       unsigned int flags;
        unsigned int type;
+       unsigned int flags;
+       unsigned int set:1;
+       unsigned int enabled:1;
+       struct cs_dsp_alg_region alg_region;
 
        void *priv;
 };