From: Kent Gibson <warthog618@gmail.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: linux-pwm@vger.kernel.org, kernel@pengutronix.de
Subject: Re: [PATCH 8/8] pwm: Add support for pwmchip devices for faster and easier userspace access
Date: Tue, 7 May 2024 09:11:03 +0800 [thread overview]
Message-ID: <20240507011103.GA26136@rigel> (raw)
In-Reply-To: <8d3acfc431ecd431d6cced032dcb58ad2579474c.1710670958.git.u.kleine-koenig@pengutronix.de>
On Sun, Mar 17, 2024 at 11:40:39AM +0100, Uwe Kleine-König wrote:
> With this change each pwmchip can be accessed from userspace via a
> character device. Compared to the sysfs-API this is faster (on a
> stm32mp157 applying a new configuration takes approx 25% only) and
> allows to pass the whole configuration in a single ioctl.
>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> new file mode 100644
> index 000000000000..ca765bfaa68d
> --- /dev/null
> +++ b/include/uapi/linux/pwm.h
> @@ -0,0 +1,23 @@
> +/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
> +
> +#ifndef _UAPI_PWM_H_
> +#define _UAPI_PWM_H_
> +
> +#include <linux/ioctl.h>
> +#include <linux/types.h>
> +
> +struct pwmchip_state {
> + unsigned int hwpwm;
> + __u64 period;
> + __u64 duty_cycle;
> + __u64 duty_offset;
> +};
> +
Sorry for being late to the party, but I only ran across this thread by
accident.
Have you considered the implications of sizing and alignment here[1]?
Change this to:
struct pwmchip_state {
__u32 hwpwm;
__u32 __pad;
__u64 period;
__u64 duty_cycle;
__u64 duty_offset;
};
to clarify?
Cheers,
Kent.
[1] https://docs.kernel.org/driver-api/ioctl.html#bit-compat-mode (and
subsequent sections)
next prev parent reply other threads:[~2024-05-07 1:11 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-17 10:40 [PATCH 0/8] pwm: Add support for character devices Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 1/8] pwm: Ensure that pwm_chips are allocated using pwmchip_alloc() Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 2/8] pwm: Give some sysfs related variables and functions better names Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 3/8] pwm: Move contents of sysfs.c into core.c Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 4/8] pwm: Ensure a struct pwm has the same lifetime as its pwm_chip Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 5/8] pwm: Add a struct device to struct pwm_chip Uwe Kleine-König
2024-03-28 18:44 ` David Lechner
2024-03-29 10:19 ` Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 6/8] pwm: Make pwmchip_[sg]et_drvdata() a wrapper around dev_set_drvdata() Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 7/8] pwm: Add more locking Uwe Kleine-König
2024-03-18 7:28 ` Thorsten Scherer
[not found] ` <CGME20240404120932eucas1p1b3c1e07bf6f41f6330725148b0268b13@eucas1p1.samsung.com>
2024-04-04 12:09 ` Marek Szyprowski
2024-04-04 15:33 ` Uwe Kleine-König
2024-03-17 10:40 ` [PATCH 8/8] pwm: Add support for pwmchip devices for faster and easier userspace access Uwe Kleine-König
2024-04-08 15:42 ` John Ernberg
2024-04-09 7:49 ` Uwe Kleine-König
2024-04-15 11:27 ` John Ernberg
2024-05-07 1:11 ` Kent Gibson [this message]
2024-05-07 6:12 ` Uwe Kleine-König
2024-04-13 9:22 ` [PATCH 0/8] pwm: Add support for character devices Uwe Kleine-König
2024-04-22 18:59 ` David Lechner
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