linux-kernel - [PATCH v4] clk: imx8qxp: Defer instead of failing probe

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Message-ID:
 <DU0PR01MB9382A24116486931F28843BA9D9C2@DU0PR01MB9382.eurprd01.prod.exchangelabs.com>
Date: Wed, 4 Sep 2024 06:50:02 +0000
From: Diogo Manuel Pais Silva <diogo.pais@...ontrol.com>
To: Peng Fan <peng.fan@....com>, Abel Vesa <abel.vesa@...aro.org>
CC: "abelvesa@...nel.org" <abelvesa@...nel.org>,
        "linux-clk@...r.kernel.org"
	<linux-clk@...r.kernel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "s.hauer@...gutronix.de"
	<s.hauer@...gutronix.de>,
        "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>,
        "sboyd@...nel.org"
	<sboyd@...nel.org>,
        "mturquette@...libre.com" <mturquette@...libre.com>,
        "festevam@...il.com" <festevam@...il.com>,
        "imx@...ts.linux.dev"
	<imx@...ts.linux.dev>,
        "EMC: linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: [PATCH v4] clk: imx8qxp: Defer instead of failing probe

When of_clk_parent_fill is ran without all the parent clocks having been
probed then the probe function will return -EINVAL, making it so that
the probe isn't attempted again. As fw_devlink is on by default this
does not usually happen, but if fw_devlink is disabled then it is very
possible that the parent clock will be probed after the lpcg first
attempt.

Signed-off-by: Diogo Silva <diogo.pais@...ontrol.com>
---
  v2: change from dev_warn to dev_err_probe
  v3: refresh patch
  v4: correctly propagate probe defer error
---
 drivers/clk/imx/clk-imx8qxp-lpcg.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/imx/clk-imx8qxp-lpcg.c b/drivers/clk/imx/clk-imx8qxp-lpcg.c
index d0ccaa040225..1c3e1a7df8ca 100644
--- a/drivers/clk/imx/clk-imx8qxp-lpcg.c
+++ b/drivers/clk/imx/clk-imx8qxp-lpcg.c
@@ -225,8 +225,8 @@ static int imx_lpcg_parse_clks_from_dt(struct platform_device *pdev,
 
 	ret = of_clk_parent_fill(np, parent_names, count);
 	if (ret != count) {
-		dev_err(&pdev->dev, "failed to get clock parent names\n");
-		return count;
+		return dev_err_probe(&pdev->dev, -EPROBE_DEFER,
+				     "failed to get all clock parent names\n");
 	}
 
 	ret = of_property_read_string_array(np, "clock-output-names",
@@ -301,6 +301,8 @@ static int imx8qxp_lpcg_clk_probe(struct platform_device *pdev)
 	ret = imx_lpcg_parse_clks_from_dt(pdev, np);
 	if (!ret)
 		return 0;
+	if (ret == -EPROBE_DEFER)
+		return ret;
 
 	ss_lpcg = of_device_get_match_data(dev);
 	if (!ss_lpcg)
-- 
2.34.1

________________________________________
From: Peng Fan <peng.fan@....com>
Sent: Wednesday, September 4, 2024 4:03 AM
To: Diogo Manuel Pais Silva; Abel Vesa
Cc: abelvesa@...nel.org; linux-clk@...r.kernel.org; shawnguo@...nel.org; kernel@...gutronix.de; s.hauer@...gutronix.de; linux-arm-kernel@...ts.infradead.org; sboyd@...nel.org; mturquette@...libre.com; festevam@...il.com; imx@...ts.linux.dev; EMC: linux-kernel@...r.kernel.org
Subject: RE: [PATCH v3] clk: imx8qxp: Defer instead of failing probe

Hi Diogo,

> Subject: [PATCH v3] clk: imx8qxp: Defer instead of failing probe
>
> When of_clk_parent_fill is ran without all the parent clocks having
> been probed then the probe function will return -EINVAL, making it so
> that the probe isn't attempted again. As fw_devlink is on by default
> this does not usually happen, but if fw_devlink is disabled then it is
> very possible that the parent clock will be probed after the lpcg first
> attempt.

Did you meet issue with fw_devlink disabled?

>
> Signed-off-by: Diogo Silva <diogo.pais@...ontrol.com>
> ---
> v2: change from dev_warn to dev_err_probe
> v3: refresh patch
> ---
>  drivers/clk/imx/clk-imx8qxp-lpcg.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/imx/clk-imx8qxp-lpcg.c b/drivers/clk/imx/clk-
> imx8qxp-lpcg.c
> index d0ccaa040225..cae8f6060fe8 100644
> --- a/drivers/clk/imx/clk-imx8qxp-lpcg.c
> +++ b/drivers/clk/imx/clk-imx8qxp-lpcg.c
> @@ -225,8 +225,8 @@ static int imx_lpcg_parse_clks_from_dt(struct
> platform_device *pdev,
>
>         ret = of_clk_parent_fill(np, parent_names, count);
>         if (ret != count) {
> -               dev_err(&pdev->dev, "failed to get clock parent names\n");
> -               return count;
> +               return dev_err_probe(&pdev->dev, -EPROBE_DEFER,
> +                                    "failed to get all clock parent
> + names\n");
>         }

The change is not enough, you also need to handle
        ret = imx_lpcg_parse_clks_from_dt(pdev, np);
        if (!ret)
                return 0;
->
        ret = imx_lpcg_parse_clks_from_dt(pdev, np);
        if (!ret)
                return 0;
        if (ret == -EPROBE_DEFER)
                return ret;

Regards,
Peng.

>
>         ret = of_property_read_string_array(np, "clock-output-names",
> --
> 2.34.1
> ________________________________________
> From: Abel Vesa <abel.vesa@...aro.org>
> Sent: Wednesday, August 28, 2024 10:31 AM
> To: Diogo Manuel Pais Silva
> Cc: Peng Fan; abelvesa@...nel.org; linux-clk@...r.kernel.org;
> shawnguo@...nel.org; kernel@...gutronix.de;
> s.hauer@...gutronix.de; linux-arm-kernel@...ts.infradead.org;
> sboyd@...nel.org; mturquette@...libre.com; festevam@...il.com;
> imx@...ts.linux.dev; EMC: linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v2] clk: imx8qxp: Defer instead of failing probe
>
> On 24-07-02 08:10:44, Diogo Manuel Pais Silva wrote:
> > When of_clk_parent_fill is ran without all the parent clocks having
> been probed then the probe function will return -EINVAL, making it so
> that the probe isn't attempted again. As fw_devlink is on by default
> this does not usually happen, but if fw_devlink is disabled then it is
> very possible that the parent clock will be probed after the lpcg first
> attempt.
> >
> > Signed-off-by: Diogo Silva <diogo.pais@...ontrol.com>
>
> This patch doesn't apply cleanly.
>
> Please respin.
>
> Thanks!
>
> > ---
> > v2: change from dev_warn to dev_err_probe
> > ---
> >  drivers/clk/imx/clk-imx8qxp-lpcg.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/clk/imx/clk-imx8qxp-lpcg.c
> > b/drivers/clk/imx/clk-imx8qxp-lpcg.c
> > index d0ccaa040225..7bd9b745edbe 100644
> > --- a/drivers/clk/imx/clk-imx8qxp-lpcg.c
> > +++ b/drivers/clk/imx/clk-imx8qxp-lpcg.c
> > @@ -225,8 +225,8 @@ static int
> imx_lpcg_parse_clks_from_dt(struct
> > platform_device *pdev,
> >
> >       ret = of_clk_parent_fill(np, parent_names, count);
> >       if (ret != count) {
> > -             dev_err(&pdev->dev, "failed to get clock parent names\n");
> > -             return count;
> > +             return dev_err_probe(&pdev->dev, -EPROBE_DEFER,
> > +                             "failed to get all clock parent
> > + names\n");
> >       }
> >
> >       ret = of_property_read_string_array(np, "clock-output-names",
> > --
> > 2.34.1