| Message ID | 20190824153707.13746-1-uwe@kleine-koenig.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | pwm: ensure pwm_apply_state() doesn't modify the state argument | expand |
On Sat, Aug 24, 2019 at 05:37:01PM +0200, Uwe Kleine-König wrote: > Hello, > > this series eventually changes the prototype of pwm_apply_state to take > a const struct pwm_state *, see the last patch for a rationale. > > Changes since v2 apart from rebasing and so covering a few more drivers > is mainly addressing the concern that after state was rounded and > applied at least pwm_get_state should return the rounded values. See > patch 2. I thought a bit on this series and there is a question about it. Depending on what is considered the right answer for it, this series might have to change. The key question is: - Is pwm_get_state() supposed to return a) the last requested configuration; or b) the last actually implemented configuration? (If the difference is unclear: consider a PWM that can only implement the following periods: 1 ms, 2 ms, 3 ms, 4 ms, 5 ms, 6 ms, ... and a consumer requested 4.2 ms. Should pwm_get_state() return .period = 4 ms (assuming this was picked) or 4.2 ms?) As of v5.3-rc5 it depends on the backend driver. For most of them 4.2 ms is returned. My series tries to push it to return 4 ms instead. (But this only works for backends that implement the .get_state() callback. And it gets more complicated as the drivers are not free of surprises.) Maybe we need functions for both answers? Best regards Uwe
Hello, this series eventually changes the prototype of pwm_apply_state to take a const struct pwm_state *, see the last patch for a rationale. Changes since v2 apart from rebasing and so covering a few more drivers is mainly addressing the concern that after state was rounded and applied at least pwm_get_state should return the rounded values. See patch 2. Uwe Kleine-König (6): pwm: introduce local struct pwm_chip in pwm_apply_state() pwm: let pwm_get_state() return the last implemented state pwm: rockchip: Don't update the state for the caller of pwm_apply_state() pwm: sun4i: Don't update the state for the caller of pwm_apply_state() pwm: fsl-ftm: Don't update the state for the caller of pwm_apply_state() pwm: ensure pwm_apply_state() doesn't modify the state argument drivers/pwm/core.c | 39 +++++++++++++++++++++-------------- drivers/pwm/pwm-atmel-hlcdc.c | 2 +- drivers/pwm/pwm-atmel.c | 2 +- drivers/pwm/pwm-bcm-iproc.c | 2 +- drivers/pwm/pwm-cros-ec.c | 2 +- drivers/pwm/pwm-fsl-ftm.c | 8 ++----- drivers/pwm/pwm-hibvt.c | 2 +- drivers/pwm/pwm-imx-tpm.c | 4 ++-- drivers/pwm/pwm-imx27.c | 2 +- drivers/pwm/pwm-jz4740.c | 2 +- drivers/pwm/pwm-lpss.c | 2 +- drivers/pwm/pwm-meson.c | 4 ++-- drivers/pwm/pwm-rcar.c | 2 +- drivers/pwm/pwm-rockchip.c | 10 ++------- drivers/pwm/pwm-sifive.c | 2 +- drivers/pwm/pwm-stm32-lp.c | 2 +- drivers/pwm/pwm-stm32.c | 4 ++-- drivers/pwm/pwm-sun4i.c | 10 ++------- drivers/pwm/pwm-zx.c | 2 +- include/linux/pwm.h | 4 ++-- 20 files changed, 49 insertions(+), 58 deletions(-)