From: Sean Young <sean@mess.org>
To: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Cc: daniel.lezcano@linaro.org, tglx@linutronix.de,
linux-kernel@vger.kernel.org, tony@atomide.com,
linux-pwm@vger.kernel.org
Subject: Re: [PATCH] drivers/clocksource/timer-ti-dm: Don't call clk_get_rate() in stop function
Date: Sat, 13 Jan 2024 16:26:40 +0000 [thread overview]
Message-ID: <ZaK5wOHxf2CvzZrk@gofer.mess.org> (raw)
In-Reply-To: <1696312220-11550-1-git-send-email-ivo.g.dimitrov.75@gmail.com>
Hi Ivaylo,
On Tue, Oct 03, 2023 at 08:50:20AM +0300, Ivaylo Dimitrov wrote:
> clk_get_rate() might sleep, and that prevents dm-timer based PWM from being
> used from atomic context.
Now that this is merged, pwm-ir-tx can only use the pwm in atomic context
if pwm-omap-timer.c sets the atomic field like the rpi pwm does here:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pwm/pwm-bcm2835.c#n175
see pwm-ir-tx here:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/media/rc/pwm-ir-tx.c#n170
It would be nice to have this tested and working properly for the n900.
Thanks,
Sean
>
> Fix that by getting fclk rate in probe() and using a notifier in case rate
> changes.
>
> Fixes: af04aa856e93 ("ARM: OMAP: Move dmtimer driver out of plat-omap to drivers under clocksource")
> Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
> ---
> drivers/clocksource/timer-ti-dm.c | 36 ++++++++++++++++++++++++++++--------
> 1 file changed, 28 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/clocksource/timer-ti-dm.c b/drivers/clocksource/timer-ti-dm.c
> index 09ab29c..5f60f6b 100644
> --- a/drivers/clocksource/timer-ti-dm.c
> +++ b/drivers/clocksource/timer-ti-dm.c
> @@ -140,6 +140,8 @@ struct dmtimer {
> struct platform_device *pdev;
> struct list_head node;
> struct notifier_block nb;
> + struct notifier_block fclk_nb;
> + unsigned long fclk_rate;
> };
>
> static u32 omap_reserved_systimers;
> @@ -253,8 +255,7 @@ static inline void __omap_dm_timer_enable_posted(struct dmtimer *timer)
> timer->posted = OMAP_TIMER_POSTED;
> }
>
> -static inline void __omap_dm_timer_stop(struct dmtimer *timer,
> - unsigned long rate)
> +static inline void __omap_dm_timer_stop(struct dmtimer *timer)
> {
> u32 l;
>
> @@ -269,7 +270,7 @@ static inline void __omap_dm_timer_stop(struct dmtimer *timer,
> * Wait for functional clock period x 3.5 to make sure that
> * timer is stopped
> */
> - udelay(3500000 / rate + 1);
> + udelay(3500000 / timer->fclk_rate + 1);
> #endif
> }
>
> @@ -348,6 +349,21 @@ static int omap_timer_context_notifier(struct notifier_block *nb,
> return NOTIFY_OK;
> }
>
> +static int omap_timer_fclk_notifier(struct notifier_block *nb,
> + unsigned long event, void *data)
> +{
> + struct clk_notifier_data *clk_data = data;
> + struct dmtimer *timer = container_of(nb, struct dmtimer, fclk_nb);
> +
> + switch (event) {
> + case POST_RATE_CHANGE:
> + timer->fclk_rate = clk_data->new_rate;
> + return NOTIFY_OK;
> + default:
> + return NOTIFY_DONE;
> + }
> +}
> +
> static int omap_dm_timer_reset(struct dmtimer *timer)
> {
> u32 l, timeout = 100000;
> @@ -754,7 +770,6 @@ static int omap_dm_timer_stop(struct omap_dm_timer *cookie)
> {
> struct dmtimer *timer;
> struct device *dev;
> - unsigned long rate = 0;
>
> timer = to_dmtimer(cookie);
> if (unlikely(!timer))
> @@ -762,10 +777,7 @@ static int omap_dm_timer_stop(struct omap_dm_timer *cookie)
>
> dev = &timer->pdev->dev;
>
> - if (!timer->omap1)
> - rate = clk_get_rate(timer->fclk);
> -
> - __omap_dm_timer_stop(timer, rate);
> + __omap_dm_timer_stop(timer);
>
> pm_runtime_put_sync(dev);
>
> @@ -1124,6 +1136,14 @@ static int omap_dm_timer_probe(struct platform_device *pdev)
> timer->fclk = devm_clk_get(dev, "fck");
> if (IS_ERR(timer->fclk))
> return PTR_ERR(timer->fclk);
> +
> + timer->fclk_nb.notifier_call = omap_timer_fclk_notifier;
> + ret = devm_clk_notifier_register(dev, timer->fclk,
> + &timer->fclk_nb);
> + if (ret)
> + return ret;
> +
> + timer->fclk_rate = clk_get_rate(timer->fclk);
> } else {
> timer->fclk = ERR_PTR(-ENODEV);
> }
> --
> 1.9.1
parent reply other threads:[~2024-01-13 16:26 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <1696312220-11550-1-git-send-email-ivo.g.dimitrov.75@gmail.com>]
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=ZaK5wOHxf2CvzZrk@gofer.mess.org \
--to=sean@mess.org \
--cc=daniel.lezcano@linaro.org \
--cc=ivo.g.dimitrov.75@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pwm@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=tony@atomide.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 read-only IMAP folder(s) and NNTP newsgroup(s).