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Diffstat (limited to 'Documentation/core-api/printk-formats.rst')
| -rw-r--r-- | Documentation/core-api/printk-formats.rst | 52 |
1 files changed, 45 insertions, 7 deletions
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst index ecccc0473da9..c0b1b6089307 100644 --- a/Documentation/core-api/printk-formats.rst +++ b/Documentation/core-api/printk-formats.rst @@ -521,7 +521,7 @@ Fwnode handles %pfw[fP] -For printing information on fwnode handles. The default is to print the full +For printing information on an fwnode_handle. The default is to print the full node name, including the path. The modifiers are functionally equivalent to %pOF above. @@ -547,11 +547,13 @@ Time and date %pt[RT]s YYYY-mm-dd HH:MM:SS %pt[RT]d YYYY-mm-dd %pt[RT]t HH:MM:SS - %pt[RT][dt][r][s] + %ptSp <seconds>.<nanoseconds> + %pt[RST][dt][r][s] For printing date and time as represented by:: - R struct rtc_time structure + R content of struct rtc_time + S content of struct timespec64 T time64_t type in human readable format. @@ -563,6 +565,11 @@ The %pt[RT]s (space) will override ISO 8601 separator by using ' ' (space) instead of 'T' (Capital T) between date and time. It won't have any effect when date or time is omitted. +The %ptSp is equivalent to %lld.%09ld for the content of the struct timespec64. +When the other specifiers are given, it becomes the respective equivalent of +%ptT[dt][r][s].%09ld. In other words, the seconds are being printed in +the human readable format followed by a dot and nanoseconds. + Passed by reference. struct clk @@ -571,9 +578,8 @@ 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 +654,38 @@ 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 ---- @@ -661,7 +699,7 @@ Do *not* use it from C. Thanks ====== -If you add other %p extensions, please extend <lib/test_printf.c> with -one or more test cases, if at all feasible. +If you add other %p extensions, please extend <lib/tests/printf_kunit.c> +with one or more test cases, if at all feasible. Thank you for your cooperation and attention. |