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Message-ID: <ce254cc123f2809976c2f2404941a9074c458309.camel@pengutronix.de>
Date: Tue, 05 Oct 2021 11:34:07 +0200
From: Philipp Zabel <p.zabel@...gutronix.de>
To: Paweł Anikiel <pan@...ihalf.com>,
miquel.raynal@...tlin.com, richard@....at, vigneshr@...com,
robh+dt@...nel.org, arnd@...db.de, olof@...om.net, soc@...nel.org,
dinguyen@...nel.org
Cc: linux-mtd@...ts.infradead.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
tn@...ihalf.com, ka@...ihalf.com, jam@...ihalf.com
Subject: Re: [PATCH 3/3] reset: socfpga: add empty driver allowing consumers
to probe
Hi Paweł,
On Mon, 2021-09-20 at 14:41 +0200, Paweł Anikiel wrote:
> The early reset driver doesn't ever probe, which causes consuming
> devices to be unable to probe. Add an empty driver to set this device
> as available, allowing consumers to probe.
>
> Signed-off-by: Paweł Anikiel <pan@...ihalf.com>
> ---
> drivers/reset/reset-socfpga.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/drivers/reset/reset-socfpga.c b/drivers/reset/reset-socfpga.c
> index 2a72f861f798..8c6492e5693c 100644
> --- a/drivers/reset/reset-socfpga.c
> +++ b/drivers/reset/reset-socfpga.c
> @@ -92,3 +92,29 @@ void __init socfpga_reset_init(void)
> for_each_matching_node(np, socfpga_early_reset_dt_ids)
> a10_reset_init(np);
> }
> +
> +/*
> + * The early driver is problematic, because it doesn't register
> + * itself as a driver. This causes certain device links to prevent
> + * consumer devices from probing. The hacky solution is to register
> + * an empty driver, whose only job is to attach itself to the reset
> + * manager and call probe.
> + */
> +static const struct of_device_id socfpga_reset_dt_ids[] = {
> + { .compatible = "altr,rst-mgr", },
> + { /* sentinel */ },
> +};
> +
> +static int reset_simple_probe(struct platform_device *pdev)
> +{
> + return 0;
> +}
> +
> +static struct platform_driver reset_socfpga_driver = {
> + .probe = reset_simple_probe,
> + .driver = {
> + .name = "socfpga-reset",
> + .of_match_table = socfpga_reset_dt_ids,
> + },
> +};
> +builtin_platform_driver(reset_socfpga_driver);
If we can just let devlink delay all consumers until the empty driver is
probed, does the reset controller have to be registered early at all?
regards
Philipp
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