Re: [PATCH v13 00/11] Convert PWM period and duty cycle to u64

[Lee Jones <lee.jones@linaro.org>]

On Tue, 21 Apr 2020, Guru Das Srinagesh wrote:

> [REQUEST]
> 
> Would it be possible for the patches that have already received Acked-by's in
> this series to be accepted and applied to the tree? I lost an Acked-by (in
> intel-panel.c) because it had a merge conflict with a new change that came in
> after I rebased to tip. I wasn't sure earlier about accepting single patches as
> opposed to the entire series en masse, but this event has got me thinking.
> 
> [COVER LETTER]
> 
> 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 v12:
>   - Rebased to tip of for-next
>   - Collected Acked-by for sun4i
>   - Reworked patch for intel-panel.c due to rebase, dropped Jani's Acked-by as
>     a result
> 
> Changes from v11:
>   - Rebased to tip of for-next.
>   - Collected "Acked-by:" for v7 (unchanged) of pwm: sifive: [4]
>   - Squished stm32-lp.c change with final patch in series
>   - sun4i: Used nsecs_to_jiffies()
>   - imx27: Added overflow handling logic
>   - clps711x: Corrected the if condition for skipping the division
>   - clk: pwm: Reverted to v8 version, added check to prevent division-by-zero
> 
> Changes from v10:
>   - Carefully added back all the "Reviewed-by: " and "Acked-by: " tags received
>     so far that had gotten missed in v9. No other changes.
> 
> Changes from v9:
>   - Gathered the received "Reviewed-by: " tag
>   - Added back the clk-pwm.c patch because kbuild test robot complained [3]
>     and addressed received review comments.
>   - clps711x: Addressed review comments.
> 
> Changes from v8:
>   - Gathered all received "Acked-by: " and "Reviewed-by: " tags
>   - Dropped patch to clk-pwm.c for reasons mentiond in [2]
>   - Expanded audience of unreviewed patches
> 
> 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/
> [2] https://lore.kernel.org/lkml/20200312190859.GA19605@codeaurora.org/
> [3] https://www.spinics.net/lists/linux-pwm/msg11906.html
> [4] https://www.spinics.net/lists/linux-pwm/msg11986.html
> 
> To: Arnd Bergmann <arnd@arndb.de>
> To: David Laight <David.Laight@ACULAB.COM>
> To: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Alexander Shiyan <shc_work@mail.ru>
> Cc: Alexandre Torgue <alexandre.torgue@st.com>
> Cc: Allison Randal <allison@lohutok.net>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Atish Patra <atish.patra@wdc.com>
> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> Cc: Chen-Yu Tsai <wens@csie.org>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Dan Carpenter <dan.carpenter@oracle.com>
> Cc: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: David Airlie <airlied@linux.ie>
> Cc: David Collins <collinsd@codeaurora.org>
> Cc: dri-devel@lists.freedesktop.org
> Cc: Fabio Estevam <festevam@gmail.com>
> Cc: Fabrice Gasnier <fabrice.gasnier@st.com>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: intel-gfx@lists.freedesktop.org
> Cc: Jean Delvare <jdelvare@suse.com>
> Cc: Jingoo Han <jingoohan1@gmail.com>
> Cc: Joe Perches <joe@perches.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Kamil Debski <kamil@wypas.org>
> Cc: Kate Stewart <kstewart@linuxfoundation.org>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Liam Girdwood <lgirdwood@gmail.com>
> Cc: linux-clk@vger.kernel.org
> Cc: linux-fbdev@vger.kernel.org
> Cc: linux-hwmon@vger.kernel.org
> Cc: linux-media@vger.kernel.org
> Cc: linux-pwm@vger.kernel.org
> Cc: linux-riscv@lists.infradead.org
> Cc: Mark Brown <broonie@kernel.org>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Michael Turquette <mturquette@baylibre.com>
> Cc: NXP Linux Team <linux-imx@nxp.com>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Paul Walmsley <paul.walmsley@sifive.com>
> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
> Cc: Philipp Zabel <p.zabel@pengutronix.de>
> Cc: Richard Fontana <rfontana@redhat.com>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: Stephen Boyd <sboyd@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
> Cc: Yash Shah <yash.shah@sifive.com>
> 
> Guru Das Srinagesh (11):
>   drm/i915: Use 64-bit division macro
>   hwmon: pwm-fan: Use 64-bit division macro
>   ir-rx51: Use 64-bit division macro
>   pwm: clps711x: Cast period to u32 before use as divisor
>   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: sun4i: Use nsecs_to_jiffies to avoid a division
>   backlight: pwm_bl: Use 64-bit division function
>   clk: pwm: Use 64-bit division function
>   pwm: core: Convert period and duty cycle to u64
> 
>  drivers/clk/clk-pwm.c                      |  7 +++-
>  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                         | 14 ++++----
>  drivers/pwm/pwm-clps711x.c                 |  5 ++-
>  drivers/pwm/pwm-imx-tpm.c                  |  2 +-
>  drivers/pwm/pwm-imx27.c                    | 53 +++++++++++++++++++++++++-----
>  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 +-

Acked-by: Lee Jones <lee.jones@linaro.org>

>  include/linux/pwm.h                        | 12 +++----
>  14 files changed, 82 insertions(+), 35 deletions(-)

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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