On Mon, Aug 14, 2023 at 02:52:49PM -0700, Dmitry Torokhov wrote: > The of_device_id structure uses a void pointer to associate additional > driver-private data with device id, most commonly used to refer to a > structure containing additional characteristics of a particular chip. > However i2c_device_id uses an unsigned long. While it can easily be > converted to a pointer, several drivers use it to store a scalar (and it > is possible to use a pointer in of_device_id to store a scalar value as > well). The worst case comes when OF part of a driver uses pointers, > while legacy part is using scalars, causing constructs like: > > data = device_get_match_data(...); > if (!data) > data = &some_array[i2c_match_id(...)->data]; > ... > > To avoid this introduce a const void "data" pointer to i2c_device_id as > well, so that we can convert drivers one by one, and drop driver_data > member in the end. > > The end goal is to clean up all helpers and make device_get_match_data() > work universally for all ACPI, DT, and legacy variants. So, we have in the parallel the activity to make buses to have a callback, why do we need this one? Looks to me as yet another 1000+ churn for not much value. What the good outcome of this is constification, but maybe we can find the way on how to prove const to stay over the kernel_ulong_t transformations for all device ID tables? -- With Best Regards, Andy Shevchenko
