From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: thierry.reding@gmail.com, lee.jones@linaro.org,
nsaenzjulienne@suse.de, f.fainelli@gmail.com, rjui@broadcom.com,
sbranden@broadcom.com, bcm-kernel-feedback-list@broadcom.com,
linux-pwm@vger.kernel.org, linux-rpi-kernel@lists.infradead.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] pwm: bcm2835: Support apply function for atomic configuration
Date: Sun, 29 Nov 2020 19:10:50 +0100 [thread overview]
Message-ID: <20201129181050.p6rkif5vjoumvafm@pengutronix.de> (raw)
In-Reply-To: <1606564926-19555-1-git-send-email-LinoSanfilippo@gmx.de>
[-- Attachment #1: Type: text/plain, Size: 2308 bytes --]
On Sat, Nov 28, 2020 at 01:02:06PM +0100, Lino Sanfilippo wrote:
> Use the newer apply function of pwm_ops instead of config, enable, disable
> and set_polarity.
>
> This guarantees atomic changes of the pwm controller configuration. It also
> reduces the size of the driver.
>
> This has been tested on a Raspberry PI 4.
>
> v2: Fixed compiler error
Changelog between review rounds go to below the tripple-dash below.
> Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
> ---
> drivers/pwm/pwm-bcm2835.c | 64 ++++++++++++++++-------------------------------
> 1 file changed, 21 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c
> index 6841dcf..dad7443 100644
> --- a/drivers/pwm/pwm-bcm2835.c
> +++ b/drivers/pwm/pwm-bcm2835.c
> @@ -58,13 +58,14 @@ static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> writel(value, pc->base + PWM_CONTROL);
> }
>
> -static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> - int duty_ns, int period_ns)
> +static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> + const struct pwm_state *state)
> {
> +
> struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> unsigned long rate = clk_get_rate(pc->clk);
> unsigned long scaler;
> - u32 period;
> + u32 value;
>
> if (!rate) {
> dev_err(pc->dev, "failed to get clock rate\n");
> @@ -72,65 +73,42 @@ static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> }
>
> scaler = DIV_ROUND_CLOSEST(NSEC_PER_SEC, rate);
> - period = DIV_ROUND_CLOSEST(period_ns, scaler);
> + /* set period */
> + value = DIV_ROUND_CLOSEST_ULL(state->period, scaler);
You're storing an unsigned long long (i.e. 64 bits) in an u32. If you
are sure that this won't discard relevant bits, please explain this in a
comment for the cursory reader.
Also note that round_closed is probably wrong, as .apply() is supposed
to round down the period to the next achievable period. (But fixing this
has to do done in a separate patch.)
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
next prev parent reply other threads:[~2020-11-29 18:11 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <202011281128.54eLfMWr-lkp@intel.com>
2020-11-28 12:02 ` [PATCH v2] pwm: bcm2835: Support apply function for atomic configuration Lino Sanfilippo
2020-11-29 18:10 ` Uwe Kleine-König [this message]
2020-12-03 23:42 ` Lino Sanfilippo
2020-12-04 8:44 ` Sean Young
2020-12-04 8:58 ` Sean Young
2020-12-04 11:13 ` Uwe Kleine-König
2020-12-04 11:38 ` Sean Young
2020-12-04 23:28 ` Uwe Kleine-König
2020-12-05 17:34 ` Sean Young
2020-12-05 19:25 ` Uwe Kleine-König
2020-12-06 14:19 ` Sean Young
2020-12-07 8:16 ` Uwe Kleine-König
2020-12-07 9:43 ` Sean Young
2020-12-07 13:52 ` Uwe Kleine-König
2020-12-07 15:29 ` Thierry Reding
2020-12-07 21:46 ` Uwe Kleine-König
2020-12-07 18:18 ` Sean Young
2020-12-08 0:00 ` Lino Sanfilippo
2020-12-08 9:07 ` Uwe Kleine-König
2020-12-04 23:16 ` Lino Sanfilippo
2020-12-04 11:21 ` Uwe Kleine-König
2020-12-04 11:40 ` Sean Young
2020-12-04 21:55 ` Uwe Kleine-König
2020-12-04 22:44 ` Sean Young
2020-12-04 23:25 ` Lino Sanfilippo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201129181050.p6rkif5vjoumvafm@pengutronix.de \
--to=u.kleine-koenig@pengutronix.de \
--cc=LinoSanfilippo@gmx.de \
--cc=bcm-kernel-feedback-list@broadcom.com \
--cc=f.fainelli@gmail.com \
--cc=lee.jones@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pwm@vger.kernel.org \
--cc=linux-rpi-kernel@lists.infradead.org \
--cc=nsaenzjulienne@suse.de \
--cc=rjui@broadcom.com \
--cc=sbranden@broadcom.com \
--cc=thierry.reding@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).