On Thu, 2020-04-02 at 11:34 +0300, Jani Nikula wrote:
On Wed, 01 Apr 2020, Sakari Ailus sakari.ailus@linux.intel.com wrote:
Add a printk modifier %ppf (for pixel format) for printing V4L2 and DRM pixel formats denoted by 4ccs. The 4cc encoding is the same for both so the same implementation can be used.
I'm not going to take a strong stand in one way or the other regarding the patch at hand, but I do think at some point we have to draw a line what should be included in printk formats. Arguably they should be reserved to things that are generally useful across large parts of the kernel, right?
Definitely yes.
I think the more specialized you get, the more you should think about just using the plain old %s, and your own helpers. Because frankly, the kernel printk specifiers also start getting more than a little obscure.
Or could we conceive of a way to make this locally extensible yet safe, letting callers use something like %{foo}, as well as providing a locally relevant function to do the conversion?
No. printf validation would be broken.