[PATCH v2 00/26] ata: optimize core code size on PATA only setups

[Bartlomiej Zolnierkiewicz]

Hi,

There have been reports in the past of libata core code size
being a problem in migration from deprecated IDE subsystem on
legacy PATA only systems, i.e.:

https://lore.kernel.org/linux-ide/db2838b7-4862-785b-3a1d-3bf09811340a@xxxxxxxxx/

This patchset re-organizes libata core code to exclude SATA
specific code from being built for PATA only setups.

The end result is up to 20% (by 20429 bytes, from 101787 bytes to
81358 bytes) smaller libata core code size (as measured for m68k
arch using modified atari_defconfig) on affected setups.

I've tested this patchset using pata_falcon driver under ARAnyM
emulator.


patches #1-10 are general fixes/cleanups done in the process of
making the patchset (there should be no inter-dependencies between
them except patch #9 which depends on patch #8)

patch #11 separates PATA timings code to libata-pata-timings.c file

patches #12-14 let compiler optimize out SATA specific code on
non-SATA hosts by adding !IS_ENABLED(CONFIG_SATA_HOST) instances

patches #15-21 separate SATA only code from libata-core.c file to
libata-sata.c one

patches #22-23 separate SATA only code from libata-scsi.c file to
libata-sata.c one

patches #24-25 separate SATA only code from libata-eh.c file to
libata-sata.c one

patch #26 makes "libata.force" kernel parameter optional


Changes since v1
(https://lore.kernel.org/linux-ide/20200128133343.29905-1-b.zolnierkie@xxxxxxxxxxx/):
- added Acked-by: tag from Tejun to "ata: remove stale maintainership
  information from core code" patch
- added Reviewed-by: tag from Martin to "ata: make SATA_PMP option
  selectable only if any SATA host driver is enabled" patch
- added Reviewed-by: tag from Christoph to following patches:
  - "ata: simplify ata_scsiop_inq_89()"
  - "ata: use COMMAND_LINE_SIZE for ata_force_param_buf[] size"
  - "ata: optimize struct ata_force_param size"
  - "ata: move EXPORT_SYMBOL_GPL()s close to exported code"
  - "ata: remove EXPORT_SYMBOL_GPL()s not used by modules"
- converted "ata: add CONFIG_SATA_HOST=n version of ata_ncq_enabled()"
  patch to use IS_ENABLED()
- added "ata: let compiler optimize out ata_dev_config_ncq() on
  non-SATA hosts" and "ata: let compiler optimize out ata_eh_set_lpm()
  on non-SATA hosts" patches
- moved "ata: move sata_scr_*() to libata-core-sata.c" patch just
  after "ata: start separating SATA specific code from libata-core.c"
  one
- dropped no longer needed patches (code savings <= 8 bytes):
  - "ata: move ata_do_link_spd_horkage() to libata-core-sata.c"
  - "ata: move ata_dev_config_ncq*() to libata-core-sata.c"
  - "ata: move sata_print_link_status() to libata-core-sata.c"
  - "ata: move sata_down_spd_limit() to libata-core-sata.c"
  - "ata: move sata_link_init_spd() to libata-core-sata.c"
  - "ata: move ata_eh_set_lpm() to libata-core-sata.c"
- removed superfluos ifdefs
- dropped file names in top of file headers
- merged libata-scsi-sata.c and libata-eh-sata.c into libata-sata.c
- emphasised in patch descriptions that atari_defconfig used for
  measurements has been modified (original one is still using
  deprecated IDE subsystem)
- added "ata: make "libata.force" kernel parameter optional" patch

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

Bartlomiej Zolnierkiewicz (26):
  ata: remove stale maintainership information from core code
  ata: expose ncq_enable_prio sysfs attribute only on NCQ capable hosts
  ata: make SATA_PMP option selectable only if any SATA host driver is
    enabled
  sata_promise: use ata_cable_sata()
  ata: simplify ata_scsiop_inq_89()
  ata: use COMMAND_LINE_SIZE for ata_force_param_buf[] size
  ata: optimize struct ata_force_param size
  ata: move EXPORT_SYMBOL_GPL()s close to exported code
  ata: remove EXPORT_SYMBOL_GPL()s not used by modules
  ata: fix CodingStyle issues in PATA timings code
  ata: separate PATA timings code from libata-core.c
  ata: add CONFIG_SATA_HOST=n version of ata_ncq_enabled()
  ata: let compiler optimize out ata_dev_config_ncq() on non-SATA hosts
  ata: let compiler optimize out ata_eh_set_lpm() on non-SATA hosts
  ata: start separating SATA specific code from libata-core.c
  ata: move sata_scr_*() to libata-sata.c
  ata: move *sata_set_spd*() to libata-sata.c
  ata: move sata_link_{debounce,resume}() to libata-sata.c
  ata: move sata_link_hardreset() to libata-sata.c
  ata: move ata_qc_complete_multiple() to libata-sata.c
  ata: move sata_deb_timing_*() to libata-sata.c
  ata: start separating SATA specific code from libata-scsi.c
  ata: move ata_sas_*() to libata-sata.c
  ata: start separating SATA specific code from libata-eh.c
  ata: move ata_eh_analyze_ncq_error() & co. to libata-sata.c
  ata: make "libata.force" kernel parameter optional

 drivers/ata/Kconfig               |   77 ++
 drivers/ata/Makefile              |    2 +
 drivers/ata/libata-core.c         | 1124 ++--------------------
 drivers/ata/libata-eh.c           |  224 +----
 drivers/ata/libata-pata-timings.c |  192 ++++
 drivers/ata/libata-sata.c         | 1483 +++++++++++++++++++++++++++++
 drivers/ata/libata-scsi.c         |  542 +----------
 drivers/ata/libata-sff.c          |    4 -
 drivers/ata/libata.h              |   25 +-
 drivers/ata/sata_promise.c        |    8 +-
 drivers/scsi/Kconfig              |    1 +
 drivers/scsi/libsas/Kconfig       |    1 +
 include/linux/libata.h            |  163 ++--
 13 files changed, 2007 insertions(+), 1839 deletions(-)
 create mode 100644 drivers/ata/libata-pata-timings.c
 create mode 100644 drivers/ata/libata-sata.c

-- 
2.24.1