On 2022/10/31 23:42, Andy Shevchenko wrote: > On Mon, Oct 31, 2022 at 09:57:51AM +0800, chenweilong wrote: >> On 2022/10/31 6:01, Andy Shevchenko wrote: >>> On Sat, Oct 29, 2022 at 07:59:36PM +0800, Weilong Chen wrote: >>>> The HiSilicon I2C controller can be used on embedded platform, which >>>> boot from devicetree. >>> ... >>> >>>> +#include <linux/acpi.h> >>>> +#include <linux/of.h> >>> Why? >>> >>> ... >>> >>>> +#ifdef CONFIG_ACPI >>> Why? >>> >>> ... >>> >>>> +#ifdef CONFIG_OF >>> Why? >>> >>> ... >>> >>>> - .acpi_match_table = hisi_i2c_acpi_ids, >>>> + .acpi_match_table = ACPI_PTR(hisi_i2c_acpi_ids), >>> Why? >>> >>> ... >>> >>>> + .of_match_table = of_match_ptr(hisi_i2c_dts_ids), >>> Why of_match_ptr()? >> There's a lot of drivers use of_match_ptr/ACPI_PTR to protect the of_device_id and >> have explicit headers file references to linux/acpi.h or linux/of.h, such as >> drivers/media/platform/intel/pxa_camera.c, >> bluetooth/hci_intel.c, >> platform/x86/intel/chtwc_int33fe.c, >> platform/x86/intel/pmc/core.c and so on. > We have a lot of the legacy or not-up-to-dated to all new kernel APIs code. > Does it justify not to use the new approach in the new contribution? > > ... > >> The acpi.h and of.h have a nice function or macro definition if CONFIG_OF/ACPI is not satisfy, >> for example: >> >> #define ACPI_PTR(_ptr) (_ptr) vs #define ACPI_PTR(_ptr) (NULL) >> >> and also a lot of 'static inline' function there. > And why do you need it? > > ... > >> Seems a good idea to remove all of them, the codes your noted may look a bit >> verbose there. But I think it is valuable for a driver and device ,telling >> users it support acpi boot or is it just embedded. > So, what do we gain here? > > (Fill the "Advantages of your code" section below) > > Disadvantages of your code: > - ugly ifdeffery which we usually do not appreciate > - in some cases it's good to have OF ID table on ACPI platforms (see what > PRP0001 trick is) > - use old approach for the compiler on how to avoid warnings of the static > variables being defined and not used (note, neither ACPI_PTR() nor > of_match_ptr() provides a new approach on that, so you have to amend them > first) > - as a side effect additional headers to be included that are used for 1% or > less of their capacity and slow down the compilation Thanks very much for your detailed explanation. By the way, is it valuable to make a cleanup for the legacy not-up-to-dated drivers? There's lots of of_match_ptr or ACPI_PTR... Best Regards.
