Hi, On Tue, 20 Aug 2024 at 07:34, Quentin Schulz <[email protected]> wrote: > > Hi, > > On 8/20/24 3:01 PM, Sahaj Sarup wrote: > > [You don't often get email from [email protected]. Learn why this is > > important at https://aka.ms/LearnAboutSenderIdentification ] > > > > On Tue, 20 Aug 2024 at 17:21, Quentin Schulz <[email protected]> > > wrote: > >> > >> Hi, > >> > >> On 8/20/24 11:12 AM, Sahaj Sarup wrote: > >>> [You don't often get email from [email protected]. Learn why this is > >>> important at https://aka.ms/LearnAboutSenderIdentification ] > >>> > >>> Hi, > >>> > >>> In `include/i2c.h` , the udevice pointer and return value definition > >>> seems to be confusing. > >>> > >>> ``` > >>> /** > >>> * i2c_get_chip_for_busnum() - get a device to use to access a chip on > >>> . > >>> . > >>> . > >>> * @devp: Returns pointer to new device if found or -ENODEV if not > >>> * found > >>> */ > >>> ``` > >>> > >>> Should this instead be: > >>> > >>> ``` > >>> * @devp: Returns pointer to new device or NULL if not found > >>> * Return: 0 on success, -ENODEV on failure > >>> ``` > >>> > >> > >> For the @devp part, seems like it as uclass_get_device_by_seq sets it to > >> NULL and i2c_get_chip only modifies it when a device is found. > >> > >> For the return part... not sure. We don't overwrite the return value we > >> get from functions we call, so not sure we can guarantee that only > >> ENODEV will be returned? > > > > make sense, devp can't return -ENODEV, ofc, and Return returns 0 or -ve. > > So it can be closer to: > > > > ``` > > * @devp: Returns pointer to new device or NULL if chip is not found > > * Return: 0 on success, -ve on failure to find bus or chip > > ``` > > > > Nothing guarantees we'll return a negative value either though, c.f. the > if conditions in i2c_get_chip_for_busnum(), where we only check for ret > (i.e. ret != 0).
That is pretty common in driver model. Few things return a positive value. Mostly they return 0 on success or a -ve error code. Note though that *devp is generally not assigned if there is an error. It is left unset, so it could be something like: @devp: Returns pointer to new device on success Regards, SImon
