Hi,

I'm trying to do an API rework of DRM, and that rewrite involves
patching a number of drivers to use a structure field instead of a
funtion call.

There's a bunch of cases that need to be covered, and I can't get all
of them to work.

So far, my current script is, with the current shortcomings as comment
below each rule.

@@
identifier fn;
identifier dev, cmd;
@@

fn (struct drm_device *dev,
    ...,
    struct drm_mode_fb_cmd2 *cmd,
    ...)
{
+ const struct drm_format_info *info = drm_get_format_info(dev, cmd);
...
- drm_format_num_planes(cmd->pixel_format)
+ info->num_planes
...
}

// This on works on most cases, ie:
// https://elixir.bootlin.com/linux/v5.0/source/drivers/gpu/drm/armada/armada_fb.c#L87
// However, for some reason unknown to me, it doesn't match:
// https://elixir.bootlin.com/linux/v5.0/source/drivers/gpu/drm/tegra/fb.c#L129

@@
identifier fb;
@@
...
struct drm_framebuffer *fb;
...
- drm_format_num_planes(fb->format->format)
+ fb->format->num_planes

// This one seems to work properly

@@
expression arg;
identifier fb;
@@
...
struct drm_framebuffer *fb;
...
- drm_format_num_planes(arg)
+ fb->format->num_planes

// This one seems to work in some cases, such as
// https://elixir.bootlin.com/linux/v5.0/source/drivers/gpu/drm/vc4/vc4_plane.c#L490
// But it also matches in cases where fb hasn't been properly assigned before, such as:
// https://elixir.bootlin.com/linux/v5.0/source/drivers/gpu/drm/tegra/fb.c#L142

@@
identifier info;
@@
...
struct drm_format_info *info;
...
- drm_format_num_planes(info->format)
+ info->num_planes

// This one seems to work too

I'm pretty new to coccinelle, so I'm not quite sure how to fix these
errors properly, even though that looks pretty simple.

Thanks!
Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com