On 05.08.2021 16:23, Jean Delvare wrote:
> On Sun, 01 Aug 2021 16:23:34 +0200, Heiner Kallweit wrote:
>> - Use an initializer for struct i2c_board_info info
>> - Use dmi_match()
>> - Simplify loop logic
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
>> ---
>> drivers/i2c/busses/i2c-i801.c | 28 +++++++++-------------------
>> 1 file changed, 9 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
>> index 958b2e14b..1ca92a1e0 100644
>> --- a/drivers/i2c/busses/i2c-i801.c
>> +++ b/drivers/i2c/busses/i2c-i801.c
>> @@ -1245,28 +1245,18 @@ static const struct {
>>
>> static void register_dell_lis3lv02d_i2c_device(struct i801_priv *priv)
>> {
>> - struct i2c_board_info info;
>> - const char *dmi_product_name;
>> + struct i2c_board_info info = { .type = "lis3lv02d" };
>
> Can it be moved to the inner loop where it is used, so that
> initialization only takes place when needed? I don't know how the
> compiler handles that, to be honest.
>
>> int i;
>>
>> - dmi_product_name = dmi_get_system_info(DMI_PRODUCT_NAME);
>> - for (i = 0; i < ARRAY_SIZE(dell_lis3lv02d_devices); ++i) {
>> - if (strcmp(dmi_product_name,
>> - dell_lis3lv02d_devices[i].dmi_product_name) == 0)
>> - break;
>> - }
>> -
>> - if (i == ARRAY_SIZE(dell_lis3lv02d_devices)) {
>> - dev_warn(&priv->pci_dev->dev,
>> - "Accelerometer lis3lv02d is present on SMBus but its"
>> - " address is unknown, skipping registration\n");
>> - return;
>> - }
>> + for (i = 0; i < ARRAY_SIZE(dell_lis3lv02d_devices); ++i)
>
> Outer block without curly braces is discouraged for readability and
> maintenance reasons (see Documentation/process/coding-style.rst section
> 3).
>
>> + if (dmi_match(DMI_PRODUCT_NAME, dell_lis3lv02d_devices[i].dmi_product_name)) {
>
> This causes dmi_get_system_info(DMI_PRODUCT_NAME) to be called for
> every iteration of the loop, slowing down the lookup. It's an exported
> function so it can't be inlined by the compiler. I know this happens
> only once, but we try to keep boot times as short as possible.
>
I'm aware of this. However we just talk about a small in-memory operation and
the performance impact should be neglectable. dmi_get_system_info() is just
the following:
const char *dmi_get_system_info(int field)
{
return dmi_ident[field];
}
EXPORT_SYMBOL(dmi_get_system_info);
I'd rate the simpler and better maintainable code higher.
But that's just a personal opinion and mileage may vary.
>> + info.addr = dell_lis3lv02d_devices[i].i2c_addr;
>> + i2c_new_client_device(&priv->adapter, &info);
>> + return;
>> + }
>>
>> - memset(&info, 0, sizeof(struct i2c_board_info));
>> - info.addr = dell_lis3lv02d_devices[i].i2c_addr;
>> - strlcpy(info.type, "lis3lv02d", I2C_NAME_SIZE);
>> - i2c_new_client_device(&priv->adapter, &info);
>> + pci_warn(priv->pci_dev,
>> + "Accelerometer lis3lv02d is present on SMBus but its address is unknown, skipping registration\n");
>> }
>>
>> /* Register optional slaves */
>
>
