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From: <Tudor.Ambarus@microchip.com>
To: <saravanak@google.com>
Cc: <corbet@lwn.net>, <gregkh@linuxfoundation.org>,
	<rafael@kernel.org>, <khilman@kernel.org>,
	<ulf.hansson@linaro.org>, <len.brown@intel.com>,
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	<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-pm@vger.kernel.org>, <linux-clk@vger.kernel.org>,
	<devicetree@vger.kernel.org>, <linux-acpi@vger.kernel.org>,
	<m.szyprowski@samsung.com>, <geert@linux-m68k.org>,
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Subject: Re: [PATCH v4 0/8] Make fw_devlink=on more forgiving
Date: Wed, 10 Feb 2021 10:02:43 +0000
Message-ID: <3ec7ba3a-bbf6-aa5f-7800-4fc91ab199ec@microchip.com> (raw)
In-Reply-To: <CAGETcx862JPn8759tk-69WySBvokxMXJaaOVY7L6V8FLwfpV8g@mail.gmail.com>

On 2/10/21 10:54 AM, Saravana Kannan wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Wed, Feb 10, 2021 at 12:19 AM <Tudor.Ambarus@microchip.com> wrote:
>>
>> Hi, Saravana,
>>
>> On 2/6/21 12:26 AM, Saravana Kannan wrote:
>>> There are a lot of devices/drivers where they never have a struct device
>>> created for them or the driver initializes the hardware without ever
>>> binding to the struct device.
>>>
>>> This series is intended to avoid any boot regressions due to such
>>> devices/drivers when fw_devlink=on and also address the handling of
>>> optional suppliers.
>>>
>>> Patch 1 and 2 addresses the issue of firmware nodes that look like
>>> they'll have struct devices created for them, but will never actually
>>> have struct devices added for them. For example, DT nodes with a
>>> compatible property that don't have devices added for them.
>>>
>>> Patch 3 and 4 allow for handling optional DT bindings.
>>>
>>> Patch 5 sets up a generic API to handle drivers that never bind with
>>> their devices.
>>>
>>> Patch 6 through 8 update different frameworks to use the new API.
>>>
>>> Thanks,
>>> Saravana
>>>
>>> Saravana Kannan (8):
>>>   driver core: fw_devlink: Detect supplier devices that will never be
>>>     added
>>>   of: property: Don't add links to absent suppliers
>>>   driver core: Add fw_devlink.strict kernel param
>>>   of: property: Add fw_devlink support for optional properties
>>>   driver core: fw_devlink: Handle suppliers that don't use driver core
>>>   irqdomain: Mark fwnodes when their irqdomain is added/removed
>>>   PM: domains: Mark fwnodes when their powerdomain is added/removed
>>>   clk: Mark fwnodes when their clock provider is added/removed
>>>
>>>  .../admin-guide/kernel-parameters.txt         |  5 ++
>>>  drivers/base/core.c                           | 58 ++++++++++++++++++-
>>>  drivers/base/power/domain.c                   |  2 +
>>>  drivers/clk/clk.c                             |  3 +
>>>  drivers/of/property.c                         | 16 +++--
>>>  include/linux/fwnode.h                        | 20 ++++++-
>>>  kernel/irq/irqdomain.c                        |  2 +
>>>  7 files changed, 98 insertions(+), 8 deletions(-)
>>>
>>
>> Even with this patch set applied, sama5d2_xplained can not boot.
>> Patch at [1] makes sama5d2_xplained boot again. Stephen applied it
>> to clk-next.
> 
> I'm glad you won't actually have any boot issues in 5.12, but the fact
> you need [1] with this series doesn't make a lot of sense to me
> because:
> 
> 1. The FWNODE_FLAG_INITIALIZED flag will be set for the clock fwnode
> in question way before any consumer devices are added.

Looks like in my case FWNODE_FLAG_INITIALIZED is not set, because
drivers/clk/at91/sama5d2.c uses of_clk_add_hw_provider().

> 2. Any consumer device added after (1) will stop trying to link to the
> clock device.
> 
> Are you somehow adding a consumer to the clock fwnode before (1)?
> 
> Can you try this patch without your clk fix? I was trying to avoid
> looping through a list, but looks like your case might somehow need
> it?
> 

I tried it, didn't solve my boot problem. The following patch makes the
sama5d2_xplained boot again, even without the patch from [1]:

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 27ff90eacb1f..9370e4dfecae 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -4594,6 +4594,8 @@ int of_clk_add_hw_provider(struct device_node *np,
        if (ret < 0)
                of_clk_del_provider(np);
 
+       fwnode_dev_initialized(&np->fwnode, true);
+
        return ret;
 }
 EXPORT_SYMBOL_GPL(of_clk_add_hw_provider);

Cheers,
ta

> -Saravana
> 
> +++ b/drivers/base/core.c
> @@ -943,6 +943,31 @@ static void device_links_missing_supplier(struct
> device *dev)
>         }
>  }
> 
> +static int fw_devlink_check_suppliers(struct device *dev)
> +{
> +       struct fwnode_link *link;
> +       int ret = 0;
> +
> +       if (!dev->fwnode ||fw_devlink_is_permissive())
> +               return 0;
> +
> +       /*
> +        * Device waiting for supplier to become available is not allowed to
> +        * probe.
> +        */
> +       mutex_lock(&fwnode_link_lock);
> +       list_for_each_entry(link, &dev->fwnode->suppliers, c_hook) {
> +               if (link->supplier->flags & FWNODE_FLAG_INITIALIZED)
> +                       continue;
> +
> +               ret = -EPROBE_DEFER;
> +               break;
> +       }
> +       mutex_unlock(&fwnode_link_lock);
> +
> +       return ret;
> +}
> +
>  /**
>   * device_links_check_suppliers - Check presence of supplier drivers.
>   * @dev: Consumer device.
> @@ -964,21 +989,13 @@ int device_links_check_suppliers(struct device *dev)
>         struct device_link *link;
>         int ret = 0;
> 
> -       /*
> -        * Device waiting for supplier to become available is not allowed to
> -        * probe.
> -        */
> -       mutex_lock(&fwnode_link_lock);
> -       if (dev->fwnode && !list_empty(&dev->fwnode->suppliers) &&
> -           !fw_devlink_is_permissive()) {
> +       if (fw_devlink_check_suppliers(dev)) {
>                 dev_dbg(dev, "probe deferral - wait for supplier %pfwP\n",
>                         list_first_entry(&dev->fwnode->suppliers,
>                         struct fwnode_link,
>                         c_hook)->supplier);
> -               mutex_unlock(&fwnode_link_lock);
>                 return -EPROBE_DEFER;
>         }
> -       mutex_unlock(&fwnode_link_lock);
> 
>         device_links_write_lock();
> 
> 
> 
>>
>> Cheers,
>> ta
>>
>> [1] https://lore.kernel.org/lkml/20210203154332.470587-1-tudor.ambarus@microchip.com/


  reply index

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20210205222651eucas1p28ef87073dea33c1c5224c14aa203bec5@eucas1p2.samsung.com>
2021-02-05 22:26 ` Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 1/8] driver core: fw_devlink: Detect supplier devices that will never be added Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 2/8] of: property: Don't add links to absent suppliers Saravana Kannan
2021-02-09 21:25     ` Rob Herring
2021-02-05 22:26   ` [PATCH v4 3/8] driver core: Add fw_devlink.strict kernel param Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 4/8] of: property: Add fw_devlink support for optional properties Saravana Kannan
2021-02-09 21:33     ` Rob Herring
2021-02-09 21:54       ` Saravana Kannan
2021-02-10  8:25         ` Geert Uytterhoeven
2021-02-05 22:26   ` [PATCH v4 5/8] driver core: fw_devlink: Handle suppliers that don't use driver core Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 6/8] irqdomain: Mark fwnodes when their irqdomain is added/removed Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 7/8] PM: domains: Mark fwnodes when their powerdomain " Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 8/8] clk: Mark fwnodes when their clock provider " Saravana Kannan
2021-02-08 15:38     ` Rob Herring
2021-02-08 23:34       ` Saravana Kannan
2021-02-10 11:44     ` [PATCH] clk: Mark fwnodes when their clock provider is added Tudor Ambarus
2021-02-10 11:44       ` Tudor Ambarus
2021-02-11 13:00         ` Greg KH
2021-02-13  0:37           ` Stephen Boyd
     [not found]         ` <CGME20210325133159eucas1p297b769beb681743fb32d362a86cc6e3e@eucas1p2.samsung.com>
2021-03-25 13:31           ` Marek Szyprowski
2021-03-25 15:47             ` Geert Uytterhoeven
2021-03-25 18:25             ` Nicolas Saenz Julienne
2021-03-26 18:13               ` Stephen Boyd
2021-03-26 18:29                 ` Geert Uytterhoeven
     [not found]                   ` <161705310317.3012082.15148238105608149214@swboyd.mtv.corp.google.com>
2021-03-29 23:28                     ` Saravana Kannan
     [not found]                       ` <161706920822.3012082.10047587064612237296@swboyd.mtv.corp.google.com>
2021-03-30  6:58                         ` Geert Uytterhoeven
     [not found]                           ` <161715734080.2260335.881350237641202575@swboyd.mtv.corp.google.com>
2021-03-31  7:05                             ` Geert Uytterhoeven
     [not found]                               ` <161721871083.2260335.2392646934517115770@swboyd.mtv.corp.google.com>
2021-04-05 11:04                                 ` Nicolas Saenz Julienne
2021-04-21  3:26         ` Guenter Roeck
2021-04-21  7:00           ` Saravana Kannan
2021-02-10 19:13       ` Saravana Kannan
2021-03-30 15:42       ` Guenter Roeck
2021-03-30 16:26         ` Saravana Kannan
     [not found]     ` <161317679292.1254594.15797939257637374295@swboyd.mtv.corp.google.com>
2021-02-14 21:15       ` [PATCH v4 8/8] clk: Mark fwnodes when their clock provider is added/removed Saravana Kannan
2021-02-06  2:45   ` [PATCH v4 0/8] Make fw_devlink=on more forgiving Saravana Kannan
2021-02-06 19:41   ` Geert Uytterhoeven
2021-02-06 20:47     ` Saravana Kannan
2021-02-08  8:40   ` Marek Szyprowski
2021-02-08 23:57     ` Saravana Kannan
2021-02-10  8:19   ` Tudor.Ambarus
2021-02-10  8:54     ` Saravana Kannan
2021-02-10 10:02       ` Tudor.Ambarus [this message]
2021-02-10 19:14         ` Saravana Kannan
2021-02-11 13:00   ` Geert Uytterhoeven
2021-02-11 13:05     ` Geert Uytterhoeven
2021-02-12  2:59     ` Saravana Kannan
2021-02-12  8:14       ` Geert Uytterhoeven
2021-02-12 20:57         ` Saravana Kannan
2021-02-15 12:38       ` Geert Uytterhoeven
2021-02-15 21:26         ` Saravana Kannan
2021-02-16  8:05           ` Geert Uytterhoeven
2021-02-16 18:48             ` Saravana Kannan
2021-02-16 20:31               ` Geert Uytterhoeven
2021-02-17 23:57                 ` Saravana Kannan
2021-02-25  9:21                   ` Geert Uytterhoeven
2021-02-15 15:16       ` Geert Uytterhoeven
2021-02-15 21:57         ` Saravana Kannan
2021-02-16 12:58           ` Geert Uytterhoeven
2021-02-15 11:19     ` Geert Uytterhoeven

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