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Message-ID: <70577604-73cb-f08f-86f8-705029bec56c@redhat.com>
Date: Tue, 27 Nov 2018 17:16:04 +0100
From: Hans de Goede <hdegoede@...hat.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Darren Hart <dvhart@...radead.org>,
platform-driver-x86@...r.kernel.org,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
linux-acpi@...r.kernel.org, Jonathan Cameron <jic23@...nel.org>,
Wolfram Sang <wsa@...-dreams.de>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
linux-i2c@...r.kernel.org,
Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 05/13] i2c: acpi: Return error pointers from
i2c_acpi_new_device()
Hi,
On 27-11-18 17:14, Hans de Goede wrote:
> Hi,
>
> On 27-11-18 16:37, Andy Shevchenko wrote:
>> The caller would like to know the reason why the i2c_acpi_new_device() fails.
>> For example, if adapter is not available, it might be in the future and we
>> would like to re-probe the clients again. But at the same time we would like to
>> bail out if the error seems unrecoverable, such as invalid argument supplied.
>> To achieve this, return error pointer in some cases.
>>
>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
>> ---
>> drivers/i2c/i2c-core-acpi.c | 21 ++++++++++++++------
>> drivers/platform/x86/i2c-multi-instantiate.c | 2 +-
>> drivers/platform/x86/intel_cht_int33fe.c | 6 +++---
>> 3 files changed, 19 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
>> index 32affd3fa8bd..7e872ceaa14f 100644
>> --- a/drivers/i2c/i2c-core-acpi.c
>> +++ b/drivers/i2c/i2c-core-acpi.c
>> @@ -386,20 +386,22 @@ struct notifier_block i2c_acpi_notifier = {
>> *
>> * Also see i2c_new_device, which this function calls to create the i2c-client.
>> *
>> - * Returns a pointer to the new i2c-client, or NULL if the adapter is not found.
>> + * Returns a pointer to the new i2c-client, or error pointer in case of failure.
>> + * Specifically, -ENODEV is returned if the adapter is not found.
>> */
>> struct i2c_client *i2c_acpi_new_device(struct device *dev, int index,
>> struct i2c_board_info *info)
>> {
>> struct i2c_acpi_lookup lookup;
>> struct i2c_adapter *adapter;
>> + struct i2c_client *client;
>> struct acpi_device *adev;
>> LIST_HEAD(resource_list);
>> int ret;
>> adev = ACPI_COMPANION(dev);
>> if (!adev)
>> - return NULL;
>> + return ERR_PTR(-EINVAL);
>> memset(&lookup, 0, sizeof(lookup));
>> lookup.info = info;
>> @@ -408,16 +410,23 @@ struct i2c_client *i2c_acpi_new_device(struct device *dev, int index,
>> ret = acpi_dev_get_resources(adev, &resource_list,
>> i2c_acpi_fill_info, &lookup);
>> + if (ret < 0)
>> + return ERR_PTR(ret);
>> +
>> acpi_dev_free_resource_list(&resource_list);
>> - if (ret < 0 || !info->addr)
>> - return NULL;
>> + if (!info->addr)
>> + return ERR_PTR(-EADDRNOTAVAIL);
>> adapter = i2c_acpi_find_adapter_by_handle(lookup.adapter_handle);
>> if (!adapter)
>> - return NULL;
>> + return ERR_PTR(-ENODEV);
>
> Why not simply return -EPROBE_DEFER here (and simplify the callers a lot).
>
> This is the only case where we really want to defer.
>
>
>> +
>> + client = i2c_new_device(adapter, info);
>> + if (!client)
>> + return ERR_PTR(-ENODEV);
>
> If you look at i2c_new_device, it can fail because it is
> out of memory, the i2c slave address is invalid, or
> their already is an i2c slave with the same address,
> iow if this were to return an ERR_PTR itself, this
> would return -ENOMEM, -EINVAL or -EBUSY and never
> -EPROBE_DEFER.
>
> Note keeping the -ENODEV here is fine, what I'm trying
> to say is that in this case the caller of i2c_acpi_new_device
> really should not return PROBE_DEFER, so directly returning
> EPROBE_DEFER above, rather then let the caller guess is better.
>
> And e.g. this:
>
> multi->clients[i] = i2c_acpi_new_device(dev, i, &board_info);
> if (IS_ERR(multi->clients[i]))
> ret = PTR_ERR(multi->clients[i]);
> else if (!multi->clients[i])
> ret = -EPROBE_DEFER; /* Wait for i2c-adapter to load */
> else
> ret = 0;
> if (ret) {
> dev_err(dev, "Error creating i2c-client, idx %d\n", i);
> goto error;
> }
>
> Can be simplified to:
>
> multi->clients[i] = i2c_acpi_new_device(dev, i, &board_info);
> if (IS_ERR(multi->clients[i])) {
> ret = PTR_ERR(multi->clients[i]);
> dev_err(dev, "Error creating i2c-client, idx %d\n", i);
> goto error;
> }
Correction, that should be:
multi->clients[i] = i2c_acpi_new_device(dev, i, &board_info);
if (IS_ERR(multi->clients[i])) {
ret = PTR_ERR(multi->clients[i]);
if (ret != -EPROBE_DEFER)
dev_err(dev, "Error creating i2c-client, idx %d\n", i);
goto error;
}
We don't want to log an error when deferring.
Regards,
Hans
>
> This will also allow you to split out the patches cleaning up the callers
> without having a bisect problem (the NULL case will now simply never happen).
>
> Regards,
>
> Hans
>
>
>> - return i2c_new_device(adapter, info);
>> + return client;
>> }
>> EXPORT_SYMBOL_GPL(i2c_acpi_new_device);
>> diff --git a/drivers/platform/x86/i2c-multi-instantiate.c b/drivers/platform/x86/i2c-multi-instantiate.c
>> index 0e3a36f3ef64..18928e4ede7f 100644
>> --- a/drivers/platform/x86/i2c-multi-instantiate.c
>> +++ b/drivers/platform/x86/i2c-multi-instantiate.c
>> @@ -72,7 +72,7 @@ static int i2c_multi_inst_probe(struct platform_device *pdev)
>> board_info.irq = ret;
>> }
>> multi->clients[i] = i2c_acpi_new_device(dev, i, &board_info);
>> - if (!multi->clients[i])
>> + if (PTR_ERR(multi->clients[i]) == -ENODEV)
>> ret = -EPROBE_DEFER; /* Wait for i2c-adapter to load */
>> else if (IS_ERR(multi->clients[i]))
>> ret = PTR_ERR(multi->clients[i]);
>
>
>> diff --git a/drivers/platform/x86/intel_cht_int33fe.c b/drivers/platform/x86/intel_cht_int33fe.c
>> index 3ba139d3bd03..b8cab17ec596 100644
>> --- a/drivers/platform/x86/intel_cht_int33fe.c
>> +++ b/drivers/platform/x86/intel_cht_int33fe.c
>> @@ -168,7 +168,7 @@ static int cht_int33fe_probe(struct platform_device *pdev)
>> board_info.dev_name = "max17047";
>> board_info.properties = max17047_props;
>> data->max17047 = i2c_acpi_new_device(dev, 1, &board_info);
>> - if (!data->max17047)
>> + if (PTR_ERR(data->max17047) == -ENODEV)
>> ret = -EPROBE_DEFER; /* Wait for i2c-adapter to load */
>> else if (IS_ERR(data->max17047))
>> ret = PTR_ERR(data->max17047);
>> @@ -200,7 +200,7 @@ static int cht_int33fe_probe(struct platform_device *pdev)
>> board_info.irq = fusb302_irq;
>> data->fusb302 = i2c_acpi_new_device(dev, 2, &board_info);
>> - if (!data->fusb302)
>> + if (PTR_ERR(data->fusb302) == -ENODEV)
>> ret = -EPROBE_DEFER; /* Wait for the i2c-adapter to load */
>> else if (IS_ERR(data->fusb302))
>> ret = PTR_ERR(data->fusb302);
>> @@ -214,7 +214,7 @@ static int cht_int33fe_probe(struct platform_device *pdev)
>> strlcpy(board_info.type, "pi3usb30532", I2C_NAME_SIZE);
>> data->pi3usb30532 = i2c_acpi_new_device(dev, 3, &board_info);
>> - if (!data->pi3usb30532)
>> + if (PTR_ERR(data->pi3usb30532) == -ENODEV)
>> ret = -EPROBE_DEFER; /* Wait for the i2c-adapter to load */
>> else if (IS_ERR(data->pi3usb30532))
>> ret = PTR_ERR(data->pi3usb30532);
>>
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