From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: "Clément Péron" <peron.clem@gmail.com>
Cc: Thierry Reding <thierry.reding@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Maxime Ripard <mripard@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
Philipp Zabel <pza@pengutronix.de>,
linux-pwm@vger.kernel.org, devicetree@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com,
Jernej Skrabec <jernej.skrabec@siol.net>
Subject: Re: [PATCH v4 3/7] pwm: sun4i: Add an optional probe for bus clock
Date: Wed, 13 Nov 2019 09:35:24 +0100 [thread overview]
Message-ID: <20191113083524.aqtf2ed4ltuiazjg@pengutronix.de> (raw)
In-Reply-To: <20191108084517.21617-4-peron.clem@gmail.com>
On Fri, Nov 08, 2019 at 09:45:13AM +0100, Clément Péron wrote:
> From: Jernej Skrabec <jernej.skrabec@siol.net>
>
> H6 PWM core needs bus clock to be enabled in order to work.
>
> Add an optional probe for it and a fallback for previous
> bindings without name on module clock.
>
> Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> Signed-off-by: Clément Péron <peron.clem@gmail.com>
> ---
> drivers/pwm/pwm-sun4i.c | 48 +++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 46 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> index 2b9a2a78591f..a10022d6c0fd 100644
> --- a/drivers/pwm/pwm-sun4i.c
> +++ b/drivers/pwm/pwm-sun4i.c
> @@ -78,6 +78,7 @@ struct sun4i_pwm_data {
>
> struct sun4i_pwm_chip {
> struct pwm_chip chip;
> + struct clk *bus_clk;
> struct clk *clk;
> struct reset_control *rst;
> void __iomem *base;
> @@ -363,9 +364,38 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
> if (IS_ERR(pwm->base))
> return PTR_ERR(pwm->base);
>
> - pwm->clk = devm_clk_get(&pdev->dev, NULL);
> - if (IS_ERR(pwm->clk))
> + /* Get all clocks and reset line */
> + pwm->clk = devm_clk_get_optional(&pdev->dev, "mod");
> + if (IS_ERR(pwm->clk)) {
> + if (PTR_ERR(pwm->rst) != -EPROBE_DEFER)
> + dev_err(&pdev->dev, "get clock failed %pe\n",
> + pwm->clk);
> return PTR_ERR(pwm->clk);
> + }
> +
> + /*
> + * Fallback for old dtbs with a single clock and no name.
> + * If a parent has a clock-name called "mod" whereas the
> + * current node is unnamed the clock reference will be
> + * incorrectly obtained and will not go into this fallback.
For me "old dtbs" suggests that today a device tree should have a "mod"
clock. Is this true also for machines other than H6? And I'd put the
comment before the acquisition of the "mod" clock. Something like:
/*
* A clock called "mod" is only required on H6 (for now) and on
* other SoCs we expect an unnamed clock. So we request "mod"
* first (and ignore the corner case that a parent provides a
* "mod" clock) and if this is not found we fall back to the
* first clock of the PWM.
*/
> + */
> + if (!pwm->clk) {
> + pwm->clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(pwm->clk)) {
> + if (PTR_ERR(pwm->rst) != -EPROBE_DEFER)
> + dev_err(&pdev->dev, "get clock failed %pe\n",
> + pwm->clk);
> + return PTR_ERR(pwm->clk);
> + }
> + }
> +
> + pwm->bus_clk = devm_clk_get_optional(&pdev->dev, "bus");
> + if (IS_ERR(pwm->bus_clk)) {
> + if (PTR_ERR(pwm->rst) != -EPROBE_DEFER)
> + dev_err(&pdev->dev, "get bus_clock failed %pe\n",
> + pwm->bus_clk);
> + return PTR_ERR(pwm->bus_clk);
> + }
>
> pwm->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
> if (IS_ERR(pwm->rst)) {
> @@ -382,6 +412,17 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
> return ret;
> }
>
> + /*
> + * We're keeping the bus clock on for the sake of simplicity.
> + * Actually it only needs to be on for hardware register
> + * accesses.
> + */
> + ret = clk_prepare_enable(pwm->bus_clk);
> + if (ret) {
> + dev_err(&pdev->dev, "Cannot prepare and enable bus_clk\n");
> + goto err_bus;
> + }
> +
Would it make sense to split this patch into "Prefer "mod" clock to
(unnamed) clock" and "Introduce optional bus clock"?
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
next prev parent reply other threads:[~2019-11-13 8:35 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-08 8:45 [PATCH v4 0/7] Add support for H6 PWM Clément Péron
2019-11-08 8:45 ` [PATCH v4 1/7] dt-bindings: pwm: allwinner: Add H6 PWM description Clément Péron
2019-11-12 19:31 ` Rob Herring
2019-11-08 8:45 ` [PATCH v4 2/7] pwm: sun4i: Add an optional probe for reset line Clément Péron
2019-11-13 8:27 ` Uwe Kleine-König
2019-11-08 8:45 ` [PATCH v4 3/7] pwm: sun4i: Add an optional probe for bus clock Clément Péron
2019-11-13 8:35 ` Uwe Kleine-König [this message]
2019-11-14 22:36 ` Clément Péron
2019-11-15 7:25 ` Uwe Kleine-König
2019-11-08 8:45 ` [PATCH v4 4/7] pwm: sun4i: Add support to output source clock directly Clément Péron
2019-11-13 8:58 ` Uwe Kleine-König
2019-11-14 22:47 ` Clément Péron
2019-11-15 7:35 ` Uwe Kleine-König
2019-11-08 8:45 ` [PATCH v4 5/7] pwm: sun4i: Add support for H6 PWM Clément Péron
2019-11-13 9:00 ` Uwe Kleine-König
2019-11-08 8:45 ` [PATCH v4 6/7] arm64: dts: allwinner: h6: Add PWM node Clément Péron
2019-11-08 8:45 ` [PATCH v4 7/7] [DO NOT MERGE] arm64: allwinner: h6: enable Beelink GS1 PWM Clément Péron
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