[PATCH v2 00/11] pwm: Allow .get_state to fail

Uwe Kleine-König
2022-11-30T15:25:19Z

Hello,

I forgot about this series and was remembered when I talked to Conor
Dooley about how .get_state() should behave in an error case.

Compared to (implicit) v1, sent with Message-Id: 20220916151506.298488-1-u.kleine-koenig@pengutronix.de
I changed:

- Patch #1 which does the prototype change now just adds "return 0" to
all implementations and so gets simpler and doesn't change behaviour.
The adaptions to the different .get_state() implementations are split
out into individual patches to ease review.
- One minor inconsistency fixed in "pwm: Handle .get_state() failures"
that I noticed while looking into this patch.
- I skipped changing sun4i.c as I don't know how to handle the error
there. Someone might want to have a look. (That's not ideal, but it's
not worse than the same issue before this series.)

In v1 Thierry had the concern:

| That raises the question about what to do in these cases. If we return
| an error, that could potentially throw off consumers. So perhaps the
| closest would be to return a disabled PWM? Or perhaps it'd be up to the
| consumer to provide some fallback configuration for invalidly configured
| or unconfigured PWMs.

.get_state() is only called in pwm_device_request on a pwm_state that a
consumer might see. Before my series a consumer might have seen a
partial modified pwm_state (because .get_state() might have modified
.period, then stumbled and returned silently). The last patch ensures
that this partial modification isn't given out to the consumer. Instead
they now see the same as if .get_state wasn't implemented at all.

Best regards
Uwe

Uwe Kleine-König (11):
pwm: Make .get_state() callback return an error code
pwm/tracing: Also record trace events for failed API calls
drm/bridge: ti-sn65dsi86: Propagate errors in .get_state() to the
caller
leds: qcom-lpg: Propagate errors in .get_state() to the caller
pwm: crc: Propagate errors in .get_state() to the caller
pwm: cros-ec: Propagate errors in .get_state() to the caller
pwm: imx27: Propagate errors in .get_state() to the caller
pwm: mtk-disp: Propagate errors in .get_state() to the caller
pwm: rockchip: Propagate errors in .get_state() to the caller
pwm: sprd: Propagate errors in .get_state() to the caller
pwm: Handle .get_state() failures

drivers/gpio/gpio-mvebu.c | 9 ++++++---
drivers/gpu/drm/bridge/ti-sn65dsi86.c | 14 ++++++++------
drivers/leds/rgb/leds-qcom-lpg.c | 14 ++++++++------
drivers/pwm/core.c | 28 +++++++++++++++++----------
drivers/pwm/pwm-atmel.c | 6 ++++--
drivers/pwm/pwm-bcm-iproc.c | 8 +++++---
drivers/pwm/pwm-crc.c | 10 ++++++----
drivers/pwm/pwm-cros-ec.c | 8 +++++---
drivers/pwm/pwm-dwc.c | 6 ++++--
drivers/pwm/pwm-hibvt.c | 6 ++++--
drivers/pwm/pwm-imx-tpm.c | 8 +++++---
drivers/pwm/pwm-imx27.c | 8 +++++---
drivers/pwm/pwm-intel-lgm.c | 6 ++++--
drivers/pwm/pwm-iqs620a.c | 6 ++++--
drivers/pwm/pwm-keembay.c | 6 ++++--
drivers/pwm/pwm-lpss.c | 6 ++++--
drivers/pwm/pwm-meson.c | 8 +++++---
drivers/pwm/pwm-mtk-disp.c | 12 +++++++-----
drivers/pwm/pwm-pca9685.c | 8 +++++---
drivers/pwm/pwm-raspberrypi-poe.c | 8 +++++---
drivers/pwm/pwm-rockchip.c | 12 +++++++-----
drivers/pwm/pwm-sifive.c | 6 ++++--
drivers/pwm/pwm-sl28cpld.c | 8 +++++---
drivers/pwm/pwm-sprd.c | 8 +++++---
drivers/pwm/pwm-stm32-lp.c | 8 +++++---
drivers/pwm/pwm-sun4i.c | 12 +++++++-----
drivers/pwm/pwm-sunplus.c | 6 ++++--
drivers/pwm/pwm-visconti.c | 6 ++++--
drivers/pwm/pwm-xilinx.c | 8 +++++---
include/linux/pwm.h | 4 ++--
include/trace/events/pwm.h | 20 +++++++++----------
31 files changed, 174 insertions(+), 109 deletions(-)

base-commit: 50315945d178eebec4e8e2c50c265767ddb926eb
--
2.38.1