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-rw-r--r--Documentation/core-api/printk-formats.rst35
1 files changed, 33 insertions, 2 deletions
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index 4bdc394e86af..4b7f3646ec6c 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -571,9 +571,8 @@ struct clk
::
%pC pll1
- %pCn pll1
-For printing struct clk structures. %pC and %pCn print the name of the clock
+For printing struct clk structures. %pC prints the name of the clock
(Common Clock Framework) or a unique 32-bit ID (legacy clock framework).
Passed by reference.
@@ -648,6 +647,38 @@ Examples::
%p4cc Y10 little-endian (0x20303159)
%p4cc NV12 big-endian (0xb231564e)
+Generic FourCC code
+-------------------
+
+::
+ %p4c[h[R]lb] gP00 (0x67503030)
+
+Print a generic FourCC code, as both ASCII characters and its numerical
+value as hexadecimal.
+
+The generic FourCC code is always printed in the big-endian format,
+the most significant byte first. This is the opposite of V4L/DRM FourCCs.
+
+The additional ``h``, ``hR``, ``l``, and ``b`` specifiers define what
+endianness is used to load the stored bytes. The data might be interpreted
+using the host, reversed host byte order, little-endian, or big-endian.
+
+Passed by reference.
+
+Examples for a little-endian machine, given &(u32)0x67503030::
+
+ %p4ch gP00 (0x67503030)
+ %p4chR 00Pg (0x30305067)
+ %p4cl gP00 (0x67503030)
+ %p4cb 00Pg (0x30305067)
+
+Examples for a big-endian machine, given &(u32)0x67503030::
+
+ %p4ch gP00 (0x67503030)
+ %p4chR 00Pg (0x30305067)
+ %p4cl 00Pg (0x30305067)
+ %p4cb gP00 (0x67503030)
+
Rust
----