[PATCH v2 07/11] pwm: imx27: Propagate errors in .get_state() to the caller

[PATCH v2 07/11] pwm: imx27: Propagate errors in .get_state() to the caller

[Uwe Kleine-König]

.get_state() can return an error indication. Make use of it to propagate
failing hardware accesses.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/pwm/pwm-imx27.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c
index 3a22c2fddc45..29a3089c534c 100644
--- a/drivers/pwm/pwm-imx27.c
+++ b/drivers/pwm/pwm-imx27.c
@@ -128,7 +128,7 @@ static int pwm_imx27_get_state(struct pwm_chip *chip,
 
 	ret = pwm_imx27_clk_prepare_enable(imx);
 	if (ret < 0)
-		return 0;
+		return ret;
 
 	val = readl(imx->mmio_base + MX3_PWMCR);
 
-- 
2.38.1


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[PATCH v2 08/11] pwm: mtk-disp: Propagate errors in .get_state() to the caller

[Uwe Kleine-König]

.get_state() can return an error indication. Make use of it to propagate
failing hardware accesses.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/pwm/pwm-mtk-disp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-mtk-disp.c b/drivers/pwm/pwm-mtk-disp.c
index 9a6bb334a31b..67e5799dd157 100644
--- a/drivers/pwm/pwm-mtk-disp.c
+++ b/drivers/pwm/pwm-mtk-disp.c
@@ -184,14 +184,14 @@ static int mtk_disp_pwm_get_state(struct pwm_chip *chip,
 	err = clk_prepare_enable(mdp->clk_main);
 	if (err < 0) {
 		dev_err(chip->dev, "Can't enable mdp->clk_main: %pe\n", ERR_PTR(err));
-		return 0;
+		return err;
 	}
 
 	err = clk_prepare_enable(mdp->clk_mm);
 	if (err < 0) {
 		dev_err(chip->dev, "Can't enable mdp->clk_mm: %pe\n", ERR_PTR(err));
 		clk_disable_unprepare(mdp->clk_main);
-		return 0;
+		return err;
 	}
 
 	rate = clk_get_rate(mdp->clk_main);
-- 
2.38.1


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[PATCH v2 09/11] pwm: rockchip: Propagate errors in .get_state() to the caller

[Uwe Kleine-König]

.get_state() can return an error indication. Make use of it to propagate
failing hardware accesses.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/pwm/pwm-rockchip.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c
index 3ec7d1756903..7f084eb34092 100644
--- a/drivers/pwm/pwm-rockchip.c
+++ b/drivers/pwm/pwm-rockchip.c
@@ -70,11 +70,11 @@ static int rockchip_pwm_get_state(struct pwm_chip *chip,
 
 	ret = clk_enable(pc->pclk);
 	if (ret)
-		return 0;
+		return ret;
 
 	ret = clk_enable(pc->clk);
 	if (ret)
-		return 0;
+		return ret;
 
 	clk_rate = clk_get_rate(pc->clk);
 
-- 
2.38.1


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Re: [PATCH v2 09/11] pwm: rockchip: Propagate errors in .get_state() to the caller

[Heiko Stübner]

Am Mittwoch, 30. November 2022, 16:21:46 CET schrieb Uwe Kleine-König:
> .get_state() can return an error indication. Make use of it to propagate
> failing hardware accesses.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Reviewed-by: Heiko Stuebner <heiko@sntech.de>



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Re: [PATCH v2 08/11] pwm: mtk-disp: Propagate errors in .get_state() to the caller

[AngeloGioacchino Del Regno]

Il 30/11/22 16:21, Uwe Kleine-König ha scritto:
> .get_state() can return an error indication. Make use of it to propagate
> failing hardware accesses.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>



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Re: [PATCH v2 00/11] pwm: Allow .get_state to fail

[Andy Shevchenko]

On Wed, Nov 30, 2022 at 04:21:37PM +0100, Uwe Kleine-König wrote:
> Hello,
> 
> I forgot about this series and was remembered when I talked to Conor
> Dooley about how .get_state() should behave in an error case.
> 
> Compared to (implicit) v1, sent with Message-Id: 20220916151506.298488-1-u.kleine-koenig@pengutronix.de
> I changed:
> 
>  - Patch #1 which does the prototype change now just adds "return 0" to
>    all implementations and so gets simpler and doesn't change behaviour.
>    The adaptions to the different .get_state() implementations are split
>    out into individual patches to ease review.
>  - One minor inconsistency fixed in "pwm: Handle .get_state() failures"
>    that I noticed while looking into this patch.
>  - I skipped changing sun4i.c as I don't know how to handle the error
>    there. Someone might want to have a look. (That's not ideal, but it's
>    not worse than the same issue before this series.)
> 
> In v1 Thierry had the concern:
> 
> | That raises the question about what to do in these cases. If we return
> | an error, that could potentially throw off consumers. So perhaps the
> | closest would be to return a disabled PWM? Or perhaps it'd be up to the
> | consumer to provide some fallback configuration for invalidly configured
> | or unconfigured PWMs.
> 
> .get_state() is only called in pwm_device_request on a pwm_state that a
> consumer might see. Before my series a consumer might have seen a
> partial modified pwm_state (because .get_state() might have modified
> .period, then stumbled and returned silently). The last patch ensures
> that this partial modification isn't given out to the consumer. Instead
> they now see the same as if .get_state wasn't implemented at all.

I'm wondering why we didn't see a compiler warning about mistyped function
prototypes in some drivers.

P.S. The series is good thing to do, thank you.

-- 
With Best Regards,
Andy Shevchenko



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Re: [PATCH v2 00/11] pwm: Allow .get_state to fail

[Uwe Kleine-König]

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Hello Andy,

On Fri, Dec 09, 2022 at 11:47:54PM +0200, Andy Shevchenko wrote:
> On Wed, Nov 30, 2022 at 04:21:37PM +0100, Uwe Kleine-König wrote:
> > In v1 Thierry had the concern:
> > 
> > | That raises the question about what to do in these cases. If we return
> > | an error, that could potentially throw off consumers. So perhaps the
> > | closest would be to return a disabled PWM? Or perhaps it'd be up to the
> > | consumer to provide some fallback configuration for invalidly configured
> > | or unconfigured PWMs.
> > 
> > .get_state() is only called in pwm_device_request on a pwm_state that a
> > consumer might see. Before my series a consumer might have seen a
> > partial modified pwm_state (because .get_state() might have modified
> > .period, then stumbled and returned silently). The last patch ensures
> > that this partial modification isn't given out to the consumer. Instead
> > they now see the same as if .get_state wasn't implemented at all.
> 
> I'm wondering why we didn't see a compiler warning about mistyped function
> prototypes in some drivers.

I don't understand where you expected a warning. Care to elaborate?

> P.S. The series is good thing to do, thank you.

It's already too late for an ack, the series is already in Thierry's
tree.

Best regards
Uwe
 
-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v2 00/11] pwm: Allow .get_state to fail

[Andy Shevchenko]

On Sat, Dec 10, 2022 at 10:18:33AM +0100, Uwe Kleine-König wrote:
> On Fri, Dec 09, 2022 at 11:47:54PM +0200, Andy Shevchenko wrote:
> > On Wed, Nov 30, 2022 at 04:21:37PM +0100, Uwe Kleine-König wrote:

...

> > I'm wondering why we didn't see a compiler warning about mistyped function
> > prototypes in some drivers.
> 
> I don't understand where you expected a warning. Care to elaborate?

intel-lpss.c has the prototype that returns an int. IIRC it was like this
before your patches. Now the above wondering passage...

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Andy Shevchenko



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Re: [PATCH v2 00/11] pwm: Allow .get_state to fail

[Uwe Kleine-König]

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Hello Andy,

On Sat, Dec 10, 2022 at 10:57:16PM +0200, Andy Shevchenko wrote:
> On Sat, Dec 10, 2022 at 10:18:33AM +0100, Uwe Kleine-König wrote:
> > On Fri, Dec 09, 2022 at 11:47:54PM +0200, Andy Shevchenko wrote:
> > > On Wed, Nov 30, 2022 at 04:21:37PM +0100, Uwe Kleine-König wrote:
> 
> ...
> 
> > > I'm wondering why we didn't see a compiler warning about mistyped function
> > > prototypes in some drivers.
> > 
> > I don't understand where you expected a warning. Care to elaborate?
> 
> intel-lpss.c has the prototype that returns an int. IIRC it was like this

Do you mean drivers/mfd/intel-lpss.c? That one doesn't implement a PWM?!

And drivers/pwm/pwm-lpss.c is adapted by this series.

One of us is confused ...

Best regards
Uwe

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Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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Re: [PATCH v2 00/11] pwm: Allow .get_state to fail

[Andy Shevchenko]

On Sat, Dec 10, 2022 at 11:41:54PM +0100, Uwe Kleine-König wrote:
> On Sat, Dec 10, 2022 at 10:57:16PM +0200, Andy Shevchenko wrote:
> > On Sat, Dec 10, 2022 at 10:18:33AM +0100, Uwe Kleine-König wrote:
> > > On Fri, Dec 09, 2022 at 11:47:54PM +0200, Andy Shevchenko wrote:
> > > > On Wed, Nov 30, 2022 at 04:21:37PM +0100, Uwe Kleine-König wrote:

...

> > > > I'm wondering why we didn't see a compiler warning about mistyped function
> > > > prototypes in some drivers.
> > > 
> > > I don't understand where you expected a warning. Care to elaborate?
> > 
> > intel-lpss.c has the prototype that returns an int. IIRC it was like this
> 
> Do you mean drivers/mfd/intel-lpss.c? That one doesn't implement a PWM?!

Nope, I meant pwm-lpss.c.

> And drivers/pwm/pwm-lpss.c is adapted by this series.

That's what I didn't see how.

> One of us is confused ...

Yes, because when I have checked the branch based on Linux Next I already saw
that get_state() returns a code and I wasn't aware that the series is already
there.

-- 
With Best Regards,
Andy Shevchenko



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