On 7/28/23 23:01, Sam Ravnborg wrote:

Hi Helge,

On Fri, Jul 28, 2023 at 08:46:59PM +0200, Helge Deller wrote:

quoted

On 7/28/23 18:39, Thomas Zimmermann wrote:

quoted

Most fbdev drivers operate on I/O memory.

Just nitpicking here:
What is I/O memory?
Isn't it either memory, or I/O ?
I mean, I would never think of the cfb* draw functions under I/O.

quoted

And most of those use the
default implementations for file I/O and console drawing. Convert all
these low-hanging fruits to the fb_ops initializer macro and Kconfig
token for fbdev I/O helpers.

I do see the motivation for your patch, but I think the
macro names are very misleading.

You have:
#define __FB_DEFAULT_IO_OPS_RDWR \
         .fb_read        = fb_io_read, \
         .fb_write       = fb_io_write

#define __FB_DEFAULT_IO_OPS_DRAW \
         .fb_fillrect    = cfb_fillrect, \
         .fb_copyarea    = cfb_copyarea, \
         .fb_imageblit   = cfb_imageblit

#define __FB_DEFAULT_IO_OPS_MMAP \
         .fb_mmap        = NULL /* default implementation */

#define FB_DEFAULT_IO_OPS \
         __FB_DEFAULT_IO_OPS_RDWR, \
         __FB_DEFAULT_IO_OPS_DRAW, \
         __FB_DEFAULT_IO_OPS_MMAP

I think FB_DEFAULT_IO_OPS is OK for read/write/mmap.
But I would suggest to split out __FB_DEFAULT_IO_OPS_DRAW.
Something like:
#define FB_DEFAULT_IO_OPS \
         __FB_DEFAULT_IO_OPS_RDWR, \
         __FB_DEFAULT_IO_OPS_MMAP

quoted

#define FB_DEFAULT_CFB_OPS \
         .fb_fillrect    = cfb_fillrect, \
         .fb_copyarea    = cfb_copyarea, \
         .fb_imageblit   = cfb_imageblit

The prefix cfb, I have recently learned, equals color frame buffer.

correct.

They are named such for purely historical reasons.

well, they operate on MEMORY which represents a (color) frame buffer,
either in host memory or memory on some card on some bus.
So, the naming cfb is not historical, but even today correct.

What is important is where the data are copied as we have two
implementations of for example copyarea - one using system memory, the
other using IO memory.

sys_copyarea() and cfb_copyarea().

The naming FB_DEFAULT_IO_OPS says this is the defaults to IO memory
operations, which tell what they do

This is exactly what I find misleading. IO_OPS sounds that it operates
on file I/O (like file read/write), but not on iomem.

and avoid the strange cfb acronym.

Reserve cfb for color frame buffers only - and maybe in the end rename
the three cfbcopyarea, cfbfillrect, cfbimgblt to use the io prefix.

Again, the io prefix is what I think is misleading.
Why not name it what it really is and what is used in the kernel already, e.g.
iomem_copyarea() and sysmem_copyarea().
which would lead to
FB_DEFAULT_IOMEM_OPS and FB_DEFAULT_SYSMEM_OPS.

Which is much simpler to do after this series - and nice extra benefit.

I hope this properly explains why I like the current naming and
acked it when the macros were introduced.

IMHO the naming isn't perfect, but that's just nitpicking.
Besides that, Thomas' patches are a nice cleanup.
So, if you want add a
Acked-by: Helge Deller <deller@gmx.de>
to the series.

Helge