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Message-ID: <CAPDyKFr9Vzgm2C6Z57Bg5mUQxg5LK6goN2og3+RC3BkTZjiqJw@mail.gmail.com>
Date: Fri, 10 May 2024 11:34:46 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Vitor Soares <ivitro@...il.com>, Lucas Stach <l.stach@...gutronix.de>
Cc: Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
Pengutronix Kernel Team <kernel@...gutronix.de>, Fabio Estevam <festevam@...il.com>,
Vitor Soares <vitor.soares@...adex.com>, linux-pm@...r.kernel.org, imx@...ts.linux.dev,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Subject: Re: [PATCH v1] pmdomain: imx8m-blk-ctrl: fix suspend/resume order
On Thu, 18 Apr 2024 at 17:52, Vitor Soares <ivitro@...il.com> wrote:
>
> From: Vitor Soares <vitor.soares@...adex.com>
>
> During the probe, the genpd power_dev is added to the dpm_list after
> blk_ctrl due to its parent/child relationship. Making the blk_ctrl
> suspend after and resume before the genpd power_dev.
>
> As a consequence, the system hangs when resuming the VPU due to the
> power domain dependency.
>
> To ensure the proper suspend/resume order, add a device link betweem
> blk_ctrl and genpd power_dev. It guarantees genpd power_dev is suspended
> after and resumed before blk-ctrl.
Before discussing $subject patch, would you mind explaining to me why
imx8m-blk-ctrl needs to use the ->suspend() callback at all?
Looking closer at that code (imx8m_blk_ctrl_suspend()), it calls
pm_runtime_get_sync() for devices to power on "everything". Why isn't
that managed by the consumer drivers (on a case by case basis) that
are managing the devices that are attached to the genpds instead?
Kind regards
Uffe
>
> Cc: <stable@...r.kernel.org>
> Closes: https://lore.kernel.org/all/fccbb040330a706a4f7b34875db1d896a0bf81c8.camel@gmail.com/
> Link: https://lore.kernel.org/all/20240409085802.290439-1-ivitro@gmail.com/
> Fixes: 2684ac05a8c4 ("soc: imx: add i.MX8M blk-ctrl driver")
> Suggested-by: Lucas Stach <l.stach@...gutronix.de>
> Signed-off-by: Vitor Soares <vitor.soares@...adex.com>
> ---
>
> This is a new patch, but is a follow-up of:
> https://lore.kernel.org/all/20240409085802.290439-1-ivitro@gmail.com/
>
> As suggested by Lucas, we are addressing this PM issue in the imx8m-blk-ctrl
> driver instead of in the imx8mm.dtsi.
>
> drivers/pmdomain/imx/imx8m-blk-ctrl.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/drivers/pmdomain/imx/imx8m-blk-ctrl.c b/drivers/pmdomain/imx/imx8m-blk-ctrl.c
> index ca942d7929c2..cd0d2296080d 100644
> --- a/drivers/pmdomain/imx/imx8m-blk-ctrl.c
> +++ b/drivers/pmdomain/imx/imx8m-blk-ctrl.c
> @@ -283,6 +283,20 @@ static int imx8m_blk_ctrl_probe(struct platform_device *pdev)
> goto cleanup_pds;
> }
>
> + /*
> + * Enforce suspend/resume ordering by making genpd power_dev a
> + * provider of blk-ctrl. Genpd power_dev is suspended after and
> + * resumed before blk-ctrl.
> + */
> + if (!device_link_add(dev, domain->power_dev, DL_FLAG_STATELESS)) {
> + ret = -EINVAL;
> + dev_err_probe(dev, ret,
> + "failed to link to %s\n", data->name);
> + pm_genpd_remove(&domain->genpd);
> + dev_pm_domain_detach(domain->power_dev, true);
> + goto cleanup_pds;
> + }
> +
> /*
> * We use runtime PM to trigger power on/off of the upstream GPC
> * domain, as a strict hierarchical parent/child power domain
> @@ -324,6 +338,7 @@ static int imx8m_blk_ctrl_probe(struct platform_device *pdev)
> of_genpd_del_provider(dev->of_node);
> cleanup_pds:
> for (i--; i >= 0; i--) {
> + device_link_remove(dev, bc->domains[i].power_dev);
> pm_genpd_remove(&bc->domains[i].genpd);
> dev_pm_domain_detach(bc->domains[i].power_dev, true);
> }
> @@ -343,6 +358,7 @@ static void imx8m_blk_ctrl_remove(struct platform_device *pdev)
> for (i = 0; bc->onecell_data.num_domains; i++) {
> struct imx8m_blk_ctrl_domain *domain = &bc->domains[i];
>
> + device_link_remove(&pdev->dev, domain->power_dev);
> pm_genpd_remove(&domain->genpd);
> dev_pm_domain_detach(domain->power_dev, true);
> }
> --
> 2.34.1
>
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