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SubjectRe: [PATCH v4 0/8] Make fw_devlink=on more forgiving
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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/

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