xiaoxiang781216 commented on a change in pull request #4504:
URL: https://github.com/apache/incubator-nuttx/pull/4504#discussion_r705904932
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File path: include/nuttx/video/fb.h
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@@ -569,6 +583,24 @@ struct fb_vtable_s
FAR const struct fb_overlayblend_s *blend);
# endif
#endif
+
+ /* Specific Controls ******************************************************/
+
+ /* Set the frequency of the framebuffer update panel (0: disable refresh) */
+
+ int (*setframerate)(FAR struct fb_vtable_s *vtable, int rate);
+
+ /* Get the frequency of the framebuffer update panel (0: disable refresh) */
+
+ int (*getframerate)(FAR struct fb_vtable_s *vtable);
+
+ /* Get the panel power status (0: full off). */
+
+ int (*getpower)(FAR struct fb_vtable_s *vtable);
+
+ /* Enable/disable panel power (0: full off). */
+
+ int (*setpower)(FAR struct fb_vtable_s *vtable, int power);
Review comment:
> It does not seem correct for the Framebuffer API to handle these
operations on the display device.
> Why not make these go through the LCD APIs?
Here are several reasons:
1. FB and LCD driver interface is already separated in the current
design(e.g. FBIOPUT_CURSOR v.s. LCDDEVIO_SETCURSOR). So, the new IOCTL(e.g.
FBIOSET_POWER) reduce the difference between two interfaces.
2. If we expose the display related operation into two device nodes, it make
the userspace GUI library integration harder, because:
- The library need to manage two handles instead one
- It's hard to identify fb/lcd pair if the device support multiple display
> I believe the expected method for powering off the display device
according to the Framebuffer API is through `fb_uninitialize`, but nobody is
currently calling it.
Two problems here:
1. LCD driver already expose LCDDEVIO_GETPOWER/LCDDEVIO_SETPOWER
2. FBIOSET_POWER accept an integer argument to specify the power level, but
is strange to pass the power level to FBIO_INIT
2. More important, up_fbuninitialize will destroy device node, and then is
impossible to reenable FB again
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