[Intel-gfx] [PATCH v8 00/12] Convert PWM period and duty cycle to u64

* [Intel-gfx] [PATCH v8 00/12] Convert PWM period and duty cycle to u64
@ 2020-03-11  1:41 Guru Das Srinagesh
  2020-03-11  1:41 ` [Intel-gfx] [PATCH v8 02/12] drm/i915: Use 64-bit division macro Guru Das Srinagesh
  0 siblings, 1 reply; 2+ messages in thread
From: Guru Das Srinagesh @ 2020-03-11  1:41 UTC (permalink / raw)
  To: linux-pwm
  Cc: Kate Stewart, linux-fbdev, David Airlie, Michael Turquette,
	Kamil Debski, dri-devel, Liam Girdwood, Atish Patra, linux-riscv,
	Lee Jones, linux-clk, Alexandre Torgue, Guru Das Srinagesh,
	Daniel Thompson, Mauro Carvalho Chehab, Alexander Shiyan,
	Fabio Estevam, Chen-Yu Tsai, NXP Linux Team, intel-gfx,
	Guenter Roeck, linux-media, Jean Delvare, Maxime Coquelin,
	Uwe Kleine-König, Bartlomiej Zolnierkiewicz, Sascha Hauer,
	Maxime Ripard, Mark Brown, Paul Walmsley,
	Subbaraman Narayanamurthy, Thomas Gleixner, Fabrice Gasnier,
	Pengutronix Kernel Team, Allison Randal, linux-hwmon,
	Richard Fontana, Stephen Boyd, Jingoo Han, linux-kernel,
	Yash Shah, Palmer Dabbelt, Philipp Zabel, Shawn Guo

Because period and duty cycle are defined in the PWM framework structs as ints
with units of nanoseconds, the maximum time duration that can be set is limited
to ~2.147 seconds. Consequently, applications desiring to set greater time
periods via the PWM framework are not be able to do so - like, for instance,
causing an LED to blink at an interval of 5 seconds.

Redefining the period and duty cycle struct members in the core PWM framework
structs as u64 values will enable larger time durations to be set and solve
this problem. Such a change to the framework mandates that drivers using these
struct members (and corresponding helper functions) also be modified correctly
in order to prevent compilation errors.

This patch series introduces the changes to all the drivers first, followed by
the framework change at the very end so that when the latter is applied, all
the drivers are in good shape and there are no compilation errors.

Changes from v7:
  - Changed commit messages of all patches to be brief and to the point.
  - Added explanation of change in cover letter.
  - Dropped change to pwm-sti.c as upon review it was unnecessary as struct
    pwm_capture is not being modified in the PWM core.

Changes from v6:
  - Split out the driver changes out into separate patches, one patch per file
    for ease of reviewing.

Changes from v5:
  - Dropped the conversion of struct pwm_capture to u64 for reasons mentioned
    in https://www.spinics.net/lists/linux-pwm/msg11541.html

Changes from v4:
  - Split the patch into two: one for changes to the drivers, and the actual
    switch to u64 for ease of reverting should the need arise.
  - Re-examined the patch and made the following corrections:
      * intel_panel.c:
	DIV64_U64_ROUND_UP -> DIV_ROUND_UP_ULL (as only the numerator would be
	64-bit in this case).
      * pwm-sti.c:
	do_div -> div_u64 (do_div is optimized only for x86 architectures, and
	div_u64's comment block suggests to use this as much as possible).

Changes from v3:
  - Rebased to current tip of for-next.

Changes from v2:
  - Fixed %u -> %llu in a dev_dbg in pwm-stm32-lp.c, thanks to kbuild test robot
  - Added a couple of fixes to pwm-imx-tpm.c and pwm-sifive.c

Changes from v1:
  - Fixed compilation errors seen when compiling for different archs.

v1:
  - Reworked the change pushed upstream earlier [1] so as to not add an
    extension to an obsolete API. With this change, pwm_ops->apply() can be
    used to set pwm_state parameters as usual.
    [1] https://lore.kernel.org/lkml/20190916140048.GB7488@ulmo/

Cc: Lee Jones <lee.jones@linaro.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jingoo Han <jingoohan1@gmail.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: linux-fbdev@vger.kernel.org
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: linux-riscv@lists.infradead.org
Cc: Yash Shah <yash.shah@sifive.com>
Cc: Atish Patra <atish.patra@wdc.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Alexander Shiyan <shc_work@mail.ru>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Richard Fontana <rfontana@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Allison Randal <allison@lohutok.net>
Cc: linux-media@vger.kernel.org
Cc: Kamil Debski <kamil@wypas.org>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Jean Delvare <jdelvare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: linux-hwmon@vger.kernel.org
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-clk@vger.kernel.org

Guru Das Srinagesh (12):
  clk: pwm: Use 64-bit division function
  drm/i915: Use 64-bit division macro
  hwmon: pwm-fan: Use 64-bit division macro
  ir-rx51: Use 64-bit division macro
  pwm: clps711x: Use 64-bit division macro
  pwm: pwm-imx-tpm: Use 64-bit division macro
  pwm: imx27: Use 64-bit division macro and function
  pwm: sifive: Use 64-bit division macro
  pwm: stm32-lp: Use %llu format specifier for period
  pwm: sun4i: Use 64-bit division function
  backlight: pwm_bl: Use 64-bit division function
  pwm: core: Convert period and duty cycle to u64

 drivers/clk/clk-pwm.c                      |  2 +-
 drivers/gpu/drm/i915/display/intel_panel.c |  2 +-
 drivers/hwmon/pwm-fan.c                    |  2 +-
 drivers/media/rc/ir-rx51.c                 |  3 ++-
 drivers/pwm/core.c                         |  4 ++--
 drivers/pwm/pwm-clps711x.c                 |  2 +-
 drivers/pwm/pwm-imx-tpm.c                  |  2 +-
 drivers/pwm/pwm-imx27.c                    |  5 ++---
 drivers/pwm/pwm-sifive.c                   |  2 +-
 drivers/pwm/pwm-stm32-lp.c                 |  2 +-
 drivers/pwm/pwm-sun4i.c                    |  2 +-
 drivers/pwm/sysfs.c                        |  8 ++++----
 drivers/video/backlight/pwm_bl.c           |  3 ++-
 include/linux/pwm.h                        | 12 ++++++------
 14 files changed, 26 insertions(+), 25 deletions(-)

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

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