From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: Wan Jiabing <wanjiabing@vivo.com>,
kernel@pengutronix.de, linux-pwm@vger.kernel.org,
linux-riscv@lists.infradead.org,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Yash Shah <yash.shah@sifive.com>,
Atish Patra <atishp@atishpatra.org>,
"Wesley W. Terpstra" <wesley@sifive.com>
Subject: [PATCH 5/7] pwm: sifive: Simplify clk handling
Date: Thu, 21 Jul 2022 12:31:27 +0200 [thread overview]
Message-ID: <20220721103129.304697-5-u.kleine-koenig@pengutronix.de> (raw)
In-Reply-To: <20220721103129.304697-1-u.kleine-koenig@pengutronix.de>
The clk is necessary for both register access and (enabled) operation of
the PWM. Instead of
clk_enable()
update_hw()
if pwm_got_enabled():
clk_enable()
elif pwm_got_disabled():
clk_disable()
clk_disable()
which is some cases only calls clk_enable() to immediately afterwards
call clk_disable again, do:
if (!prev_state.enabled)
clk_enable()
# clk enabled exactly once
update_hw()
if (!next_state.enabled)
clk_disable()
which is much easier.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
drivers/pwm/pwm-sifive.c | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
index d833536b5e7a..34d23d56fa25 100644
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -168,24 +168,24 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
}
mutex_unlock(&ddata->lock);
- ret = clk_enable(ddata->clk);
- if (ret) {
- dev_err(ddata->chip.dev, "Enable clk failed\n");
- return ret;
+ /*
+ * If the PWM is enabled the clk is already on. So only enable it
+ * conditionally to have it on exactly once afterwards independent of
+ * the PWM state.
+ */
+ if (!enabled) {
+ ret = clk_enable(ddata->clk);
+ if (ret) {
+ dev_err(ddata->chip.dev, "Enable clk failed\n");
+ return ret;
+ }
}
writel(frac, ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
- if (state->enabled != enabled) {
- if (state->enabled) {
- if (clk_enable(ddata->clk))
- dev_err(ddata->chip.dev, "Enable clk failed\n");
- } else {
- clk_disable(ddata->clk);
- }
- }
+ if (!state->enabled)
+ clk_disable(ddata->clk);
- clk_disable(ddata->clk);
return 0;
}
--
2.36.1
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2022-07-21 10:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-21 10:31 [PATCH 1/7] pwm: sifive: Simplify offset calculation for PWMCMP registers Uwe Kleine-König
2022-07-21 10:31 ` [PATCH 2/7] pwm: sifive: Fold pwm_sifive_enable() into its only caller Uwe Kleine-König
2022-07-21 10:31 ` [PATCH 3/7] pwm: sifive: Reduce time the controller lock is held Uwe Kleine-König
2022-07-21 10:31 ` [PATCH 4/7] pwm: sifive: Enable clk only after period check in .apply() Uwe Kleine-König
2022-07-21 10:31 ` Uwe Kleine-König [this message]
2022-07-21 10:31 ` [PATCH 6/7] pwm: sifive: Ensure the clk is enabled exactly one per running PWM Uwe Kleine-König
2022-07-21 20:45 ` Uwe Kleine-König
2022-07-28 17:10 ` Thierry Reding
2022-07-21 10:31 ` [PATCH 7/7] pwm: sifive: Shut down hardware only after pwmchip_remove() completed Uwe Kleine-König
2022-07-22 17:45 ` Emil Renner Berthing
2022-07-28 17:12 ` Thierry Reding
2022-07-28 17:45 ` Conor.Dooley
2022-07-28 17:12 ` [PATCH 1/7] pwm: sifive: Simplify offset calculation for PWMCMP registers Thierry Reding
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=20220721103129.304697-5-u.kleine-koenig@pengutronix.de \
--to=u.kleine-koenig@pengutronix.de \
--cc=atishp@atishpatra.org \
--cc=kernel@pengutronix.de \
--cc=linux-pwm@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=thierry.reding@gmail.com \
--cc=wanjiabing@vivo.com \
--cc=wesley@sifive.com \
--cc=yash.shah@sifive.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).