On Fri, Oct 6, 2023 at 8:33 PM Michal Wilczynski
<michal.wilczynski@xxxxxxxxx> wrote:
>
> NFIT driver uses struct acpi_driver incorrectly to register itself.
> This is wrong as the instances of the ACPI devices are not meant
> to be literal devices, they're supposed to describe ACPI entry of a
> particular device.
>
> Use platform_driver instead of acpi_driver. In relevant places call
> platform devices instances pdev to make a distinction with ACPI
> devices instances.
>
> NFIT driver uses devm_*() family of functions extensively. This change
> has no impact on correct functioning of the whole devm_*() family of
> functions, since the lifecycle of the device stays the same. It is still
> being created during the enumeration, and destroyed on platform device
> removal.
>
> Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Signed-off-by: Michal Wilczynski <michal.wilczynski@xxxxxxxxx>
> ---
> drivers/acpi/nfit/core.c | 34 ++++++++++++++++++----------------
> 1 file changed, 18 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index 942b84d94078..fb0bc16fa186 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -15,6 +15,7 @@
> #include <linux/sort.h>
> #include <linux/io.h>
> #include <linux/nd.h>
> +#include <linux/platform_device.h>
> #include <asm/cacheflush.h>
> #include <acpi/nfit.h>
> #include "intel.h"
> @@ -98,7 +99,7 @@ static struct acpi_device *to_acpi_dev(struct acpi_nfit_desc *acpi_desc)
> || strcmp(nd_desc->provider_name, "ACPI.NFIT") != 0)
> return NULL;
>
> - return to_acpi_device(acpi_desc->dev);
> + return ACPI_COMPANION(acpi_desc->dev);
> }
>
> static int xlat_bus_status(void *buf, unsigned int cmd, u32 status)
> @@ -3284,11 +3285,11 @@ static void acpi_nfit_put_table(void *table)
>
> static void acpi_nfit_notify(acpi_handle handle, u32 event, void *data)
> {
> - struct acpi_device *adev = data;
> + struct device *dev = data;
>
> - device_lock(&adev->dev);
> - __acpi_nfit_notify(&adev->dev, handle, event);
> - device_unlock(&adev->dev);
> + device_lock(dev);
> + __acpi_nfit_notify(dev, handle, event);
> + device_unlock(dev);
Careful here.
The ACPI device locking is changed to platform device locking without
a word of explanation in the changelog.
Do you actually know what the role of the locking around
__acpi_nfit_notify() is and whether or not it can be replaced with
platform device locking safely?
> }
>
> static void acpi_nfit_remove_notify_handler(void *data)
> @@ -3329,11 +3330,12 @@ void acpi_nfit_shutdown(void *data)
> }
> EXPORT_SYMBOL_GPL(acpi_nfit_shutdown);
>
> -static int acpi_nfit_add(struct acpi_device *adev)
> +static int acpi_nfit_probe(struct platform_device *pdev)
> {
> struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
> struct acpi_nfit_desc *acpi_desc;
> - struct device *dev = &adev->dev;
> + struct device *dev = &pdev->dev;
> + struct acpi_device *adev = ACPI_COMPANION(dev);
> struct acpi_table_header *tbl;
> acpi_status status = AE_OK;
> acpi_size sz;
> @@ -3360,7 +3362,7 @@ static int acpi_nfit_add(struct acpi_device *adev)
> acpi_desc = devm_kzalloc(dev, sizeof(*acpi_desc), GFP_KERNEL);
> if (!acpi_desc)
> return -ENOMEM;
> - acpi_nfit_desc_init(acpi_desc, &adev->dev);
> + acpi_nfit_desc_init(acpi_desc, dev);
You seem to think that replacing adev->dev with pdev->dev everywhere
in this driver will work,
Have you verified that in any way? If so, then how?
>
> /* Save the acpi header for exporting the revision via sysfs */
> acpi_desc->acpi_header = *tbl;
> @@ -3391,7 +3393,7 @@ static int acpi_nfit_add(struct acpi_device *adev)
> return rc;
>
> rc = acpi_dev_install_notify_handler(adev, ACPI_DEVICE_NOTIFY,
> - acpi_nfit_notify, adev);
> + acpi_nfit_notify, dev);
> if (rc)
> return rc;
>
> @@ -3475,11 +3477,11 @@ static const struct acpi_device_id acpi_nfit_ids[] = {
> };
> MODULE_DEVICE_TABLE(acpi, acpi_nfit_ids);
>
> -static struct acpi_driver acpi_nfit_driver = {
> - .name = KBUILD_MODNAME,
> - .ids = acpi_nfit_ids,
> - .ops = {
> - .add = acpi_nfit_add,
> +static struct platform_driver acpi_nfit_driver = {
> + .probe = acpi_nfit_probe,
> + .driver = {
> + .name = KBUILD_MODNAME,
> + .acpi_match_table = acpi_nfit_ids,
> },
> };
>
> @@ -3517,7 +3519,7 @@ static __init int nfit_init(void)
> return -ENOMEM;
>
> nfit_mce_register();
> - ret = acpi_bus_register_driver(&acpi_nfit_driver);
> + ret = platform_driver_register(&acpi_nfit_driver);
> if (ret) {
> nfit_mce_unregister();
> destroy_workqueue(nfit_wq);
> @@ -3530,7 +3532,7 @@ static __init int nfit_init(void)
> static __exit void nfit_exit(void)
> {
> nfit_mce_unregister();
> - acpi_bus_unregister_driver(&acpi_nfit_driver);
> + platform_driver_unregister(&acpi_nfit_driver);
> destroy_workqueue(nfit_wq);
> WARN_ON(!list_empty(&acpi_descs));
> }
> --
