[1/5] misc: eeprom: at24: Initialise AT24 NVMEM ID field

Message ID 20200910134239.192030-2-jonathanh@nvidia.com
State New
Headers show
Series
  • [1/5] misc: eeprom: at24: Initialise AT24 NVMEM ID field
Related show

Commit Message

Jon Hunter Sept. 10, 2020, 1:42 p.m.
The AT24 EEPROM driver does not initialise the 'id' field of the
nvmem_config structure and because the entire structure is not
initialised, it ends up with a random value. This causes the NVMEM
driver to append the device 'devid' value to name of the NVMEM
device. Although this is not a problem per-se, for I2C devices such as
the AT24, that already have a device unique name, there does not seem
much value in appending an additional 0 to the I2C name. For example,
appending a 0 to an I2C device name such as 1-0050 does not seem
necessary and maybe even a bit confusing. Therefore, fix this by
setting the NVMEM config.id to NVMEM_DEVID_NONE for AT24 EEPROMs.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
---
 drivers/misc/eeprom/at24.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Bartosz Golaszewski Sept. 10, 2020, 3:35 p.m. | #1
On Thu, Sep 10, 2020 at 3:43 PM Jon Hunter <jonathanh@nvidia.com> wrote:
>
> The AT24 EEPROM driver does not initialise the 'id' field of the
> nvmem_config structure and because the entire structure is not
> initialised, it ends up with a random value. This causes the NVMEM
> driver to append the device 'devid' value to name of the NVMEM
> device. Although this is not a problem per-se, for I2C devices such as
> the AT24, that already have a device unique name, there does not seem
> much value in appending an additional 0 to the I2C name. For example,
> appending a 0 to an I2C device name such as 1-0050 does not seem
> necessary and maybe even a bit confusing. Therefore, fix this by
> setting the NVMEM config.id to NVMEM_DEVID_NONE for AT24 EEPROMs.
>
> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
> ---
>  drivers/misc/eeprom/at24.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> index e9df1ca251df..3f7a3bb6a36c 100644
> --- a/drivers/misc/eeprom/at24.c
> +++ b/drivers/misc/eeprom/at24.c
> @@ -715,6 +715,7 @@ static int at24_probe(struct i2c_client *client)
>
>         nvmem_config.name = dev_name(dev);
>         nvmem_config.dev = dev;
> +       nvmem_config.id = NVMEM_DEVID_NONE;
>         nvmem_config.read_only = !writable;
>         nvmem_config.root_only = !(flags & AT24_FLAG_IRUGO);
>         nvmem_config.owner = THIS_MODULE;
> --
> 2.25.1
>

This patch is correct and thanks for catching it. I vaguely recall
wondering at some point why the appended 0 in the nvmem name for at24.
Unfortunately this change would affect how the device is visible in
user-space in /sys/bus/nvmem/devices/ and this could break existing
users. Also: there are many in-kernel users that would need to be
updated. I'm afraid we'll need some sort of backward compatibility.

Bartosz

Patch

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index e9df1ca251df..3f7a3bb6a36c 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -715,6 +715,7 @@  static int at24_probe(struct i2c_client *client)
 
 	nvmem_config.name = dev_name(dev);
 	nvmem_config.dev = dev;
+	nvmem_config.id = NVMEM_DEVID_NONE;
 	nvmem_config.read_only = !writable;
 	nvmem_config.root_only = !(flags & AT24_FLAG_IRUGO);
 	nvmem_config.owner = THIS_MODULE;