From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Stephen Boyd <sboyd@kernel.org>,
Michael Turquette <mturquette@baylibre.com>,
linux-spi <linux-spi@vger.kernel.org>,
Mark Brown <broonie@kernel.org>,
Sascha Hauer <kernel@pengutronix.de>,
linux-clk <linux-clk@vger.kernel.org>
Subject: Re: [PATCH v4 6/6] spi: davinci: Simplify using devm_clk_get_enabled()
Date: Wed, 7 Apr 2021 09:24:39 +0200 [thread overview]
Message-ID: <20210407072439.niicbbvdzuegkagf@pengutronix.de> (raw)
In-Reply-To: <CAMuHMdXD3UgbLWD2pEc-Y=OstdYn0riuBaXFZvwZMQ0Xem6soA@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 3496 bytes --]
On Wed, Apr 07, 2021 at 09:00:33AM +0200, Geert Uytterhoeven wrote:
> Hi Uwe,
>
> I'm not Mark, but I'd like to share my 2€c.
>
> On Tue, Apr 6, 2021 at 3:43 PM Uwe Kleine-König
> <u.kleine-koenig@pengutronix.de> wrote:
> > On Wed, Mar 31, 2021 at 01:02:12PM +0100, Mark Brown wrote:
> > > On Tue, Mar 30, 2021 at 08:17:55PM +0200, Uwe Kleine-König wrote:
> > > > devm_clk_get_enabled() returns the clk already (prepared and) enabled
> > > > and the automatically called cleanup cares for disabling (and
> > > > unpreparing). So simplify .probe() and .remove() accordingly.
> > >
> > > Acked-by: Mark Brown <broonie@kernel.org>
> >
> > Thanks. I wonder what you think about this series. Is it more "Well, ok,
> > if you must, the change you did to this spi driver looks correct." or
> > "This is a good simplification and a similar change for nearly all other
> > spi drivers that make use of a clk is possible, too. Dear clk
> > maintainers, please go forward and apply this useful series."?
>
> While this simplifies drivers, this makes it harder to add power
> management by controlling the clocks through Runtime PM later, as that
> will require reverting the s/devm_clk_get/devm_clk_get_enabled/ again.
Hmm, if you start with a driver that uses devm_clk_get_enabled() you
have to do:
diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
index 63ee918ecdb0..07855f89290e 100644
--- a/drivers/spi/spi-davinci.c
+++ b/drivers/spi/spi-davinci.c
@@ -936,7 +936,7 @@ static int davinci_spi_probe(struct platform_device *pdev)
dspi->bitbang.master = master;
- dspi->clk = devm_clk_get_enabled(&pdev->dev, NULL);
+ dspi->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(dspi->clk)) {
ret = -ENODEV;
goto free_master;
(+ adding runtime PM of course). When you start with the previous state
of the driver you have to do:
diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
index 7453a1dbbc06..07855f89290e 100644
--- a/drivers/spi/spi-davinci.c
+++ b/drivers/spi/spi-davinci.c
@@ -941,9 +941,6 @@ static int davinci_spi_probe(struct platform_device *pdev)
ret = -ENODEV;
goto free_master;
}
- ret = clk_prepare_enable(dspi->clk);
- if (ret)
- goto free_master;
master->use_gpio_descriptors = true;
master->dev.of_node = pdev->dev.of_node;
@@ -968,7 +965,7 @@ static int davinci_spi_probe(struct platform_device *pdev)
ret = davinci_spi_request_dma(dspi);
if (ret == -EPROBE_DEFER) {
- goto free_clk;
+ goto free_master;
} else if (ret) {
dev_info(&pdev->dev, "DMA is not supported (%d)\n", ret);
dspi->dma_rx = NULL;
@@ -1012,8 +1009,6 @@ static int davinci_spi_probe(struct platform_device *pdev)
dma_release_channel(dspi->dma_rx);
dma_release_channel(dspi->dma_tx);
}
-free_clk:
- clk_disable_unprepare(dspi->clk);
free_master:
spi_master_put(master);
err:
@@ -1039,8 +1034,6 @@ static int davinci_spi_remove(struct platform_device *pdev)
spi_bitbang_stop(&dspi->bitbang);
- clk_disable_unprepare(dspi->clk);
-
if (dspi->dma_rx) {
dma_release_channel(dspi->dma_rx);
dma_release_channel(dspi->dma_tx);
(+ again adding runtime PM of course). Do you really think the latter is
the easier approach? Or what am I missing?
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:[~2021-04-07 7:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-30 18:17 [PATCH v4 0/6] clk: provide new devm helpers for prepared and enabled clocks Uwe Kleine-König
2021-03-30 18:17 ` [PATCH v4 1/6] clk: generalize devm_clk_get() a bit Uwe Kleine-König
2021-03-30 18:17 ` [PATCH v4 2/6] clk: Provide new devm_clk_helpers for prepared and enabled clocks Uwe Kleine-König
2021-03-30 18:17 ` [PATCH v4 6/6] spi: davinci: Simplify using devm_clk_get_enabled() Uwe Kleine-König
2021-03-31 12:02 ` Mark Brown
2021-04-06 6:57 ` Uwe Kleine-König
2021-04-07 7:00 ` Geert Uytterhoeven
2021-04-07 7:24 ` Uwe Kleine-König [this message]
2021-04-07 11:02 ` Mark Brown
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=20210407072439.niicbbvdzuegkagf@pengutronix.de \
--to=u.kleine-koenig@pengutronix.de \
--cc=broonie@kernel.org \
--cc=geert@linux-m68k.org \
--cc=kernel@pengutronix.de \
--cc=linux-clk@vger.kernel.org \
--cc=linux-spi@vger.kernel.org \
--cc=mturquette@baylibre.com \
--cc=sboyd@kernel.org \
/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).