diff mbox series

[v7,1/3] lib/vsprintf: Add support for printing V4L2 and DRM fourccs

Message ID 20210215114030.11862-2-sakari.ailus@linux.intel.com (mailing list archive)
State New, archived
Headers show
Series Add %p4cc printk modifier for V4L2 and DRM fourcc codes | expand

Commit Message

Sakari Ailus Feb. 15, 2021, 11:40 a.m. UTC 
Add a printk modifier %p4cc (for pixel format) for printing V4L2 and DRM
pixel formats denoted by fourccs. The fourcc encoding is the same for both
so the same implementation can be used.

Suggested-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 Documentation/core-api/printk-formats.rst | 16 ++++++++++
 lib/test_printf.c                         | 17 ++++++++++
 lib/vsprintf.c                            | 39 +++++++++++++++++++++++
 scripts/checkpatch.pl                     |  6 ++--
 4 files changed, 76 insertions(+), 2 deletions(-)

Comments

Andy Shevchenko Feb. 15, 2021, 1:31 p.m. UTC | #1 
On Mon, Feb 15, 2021 at 01:40:28PM +0200, Sakari Ailus wrote:
> Add a printk modifier %p4cc (for pixel format) for printing V4L2 and DRM
> pixel formats denoted by fourccs. The fourcc encoding is the same for both
> so the same implementation can be used.

This version I almost like, feel free to add
Reviewed-by: From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
after considering addressing below nit-picks.

> Suggested-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Reviewed-by: Petr Mladek <pmladek@suse.com>
> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> ---
>  Documentation/core-api/printk-formats.rst | 16 ++++++++++
>  lib/test_printf.c                         | 17 ++++++++++
>  lib/vsprintf.c                            | 39 +++++++++++++++++++++++
>  scripts/checkpatch.pl                     |  6 ++--
>  4 files changed, 76 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
> index 160e710d992f..da2aa065dc42 100644
> --- a/Documentation/core-api/printk-formats.rst
> +++ b/Documentation/core-api/printk-formats.rst
> @@ -567,6 +567,22 @@ For printing netdev_features_t.
>  
>  Passed by reference.
>  
> +V4L2 and DRM FourCC code (pixel format)
> +---------------------------------------
> +
> +::
> +
> +	%p4cc
> +
> +Print a FourCC code used by V4L2 or DRM, including format endianness and
> +its numerical value as hexadecimal.
> +
> +Passed by reference.
> +
> +Examples::
> +
> +	%p4cc	BG12 little-endian (0x32314742)

No examples with spaces / non-printable / non-ascii characters

> +
>  Thanks
>  ======
>  
> diff --git a/lib/test_printf.c b/lib/test_printf.c
> index 7d60f24240a4..9848510a2786 100644
> --- a/lib/test_printf.c
> +++ b/lib/test_printf.c
> @@ -647,6 +647,22 @@ static void __init fwnode_pointer(void)
>  	software_node_unregister_nodes(softnodes);
>  }
>  
> +static void __init fourcc_pointer(void)
> +{
> +	struct {
> +		u32 code;
> +		char *str;
> +	} const try[] = {
> +		{ 0x3231564e, "NV12 little-endian (0x3231564e)", },
> +		{ 0xb231564e, "NV12 big-endian (0xb231564e)", },
> +		{ 0x10111213, ".... little-endian (0x10111213)", },
> +	};
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(try); i++)
> +		test(try[i].str, "%p4cc", &try[i].code);
> +}
> +
>  static void __init
>  errptr(void)
>  {
> @@ -692,6 +708,7 @@ test_pointer(void)
>  	flags();
>  	errptr();
>  	fwnode_pointer();
> +	fourcc_pointer();
>  }
>  
>  static void __init selftest(void)
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 3b53c73580c5..432b5a2d1e90 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1733,6 +1733,42 @@ char *netdev_bits(char *buf, char *end, const void *addr,
>  	return special_hex_number(buf, end, num, size);
>  }
>  
> +static noinline_for_stack
> +char *fourcc_string(char *buf, char *end, const u32 *fourcc,
> +		    struct printf_spec spec, const char *fmt)
> +{
> +	char output[sizeof("1234 little-endian (0x01234567)")];

1234 -> ABCD ? (Or XY12 to be closer to the reality)

> +	char *p = output;
> +	unsigned int i;
> +	u32 val;
> +
> +	if (fmt[1] != 'c' || fmt[2] != 'c')
> +		return error_string(buf, end, "(%p4?)", spec);
> +
> +	if (check_pointer(&buf, end, fourcc, spec))
> +		return buf;
> +
> +	val = *fourcc & ~BIT(31);
> +
> +	for (i = 0; i < sizeof(*fourcc); i++) {
> +		unsigned char c = val >> (i * 8);
> +
> +		/* Print non-control ASCII characters as-is, dot otherwise */
> +		*p++ = isascii(c) && isprint(c) ? c : '.';
> +	}
> +
> +	strcpy(p, *fourcc & BIT(31) ? " big-endian" : " little-endian");
> +	p += strlen(p);
> +
> +	*p++ = ' ';
> +	*p++ = '(';
> +	p = special_hex_number(p, output + sizeof(output) - 2, *fourcc, sizeof(u32));
> +	*p++ = ')';
> +	*p = '\0';
> +
> +	return string(buf, end, output, spec);
> +}
> +
>  static noinline_for_stack
>  char *address_val(char *buf, char *end, const void *addr,
>  		  struct printf_spec spec, const char *fmt)
> @@ -2162,6 +2198,7 @@ char *fwnode_string(char *buf, char *end, struct fwnode_handle *fwnode,
>   *       correctness of the format string and va_list arguments.
>   * - 'K' For a kernel pointer that should be hidden from unprivileged users
>   * - 'NF' For a netdev_features_t
> + * - '4cc' V4L2 or DRM FourCC code, with endianness and raw numerical value.
>   * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with
>   *            a certain separator (' ' by default):
>   *              C colon
> @@ -2259,6 +2296,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
>  		return restricted_pointer(buf, end, ptr, spec);
>  	case 'N':
>  		return netdev_bits(buf, end, ptr, spec, fmt);
> +	case '4':
> +		return fourcc_string(buf, end, ptr, spec, fmt);
>  	case 'a':
>  		return address_val(buf, end, ptr, spec, fmt);
>  	case 'd':
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 92e888ed939f..79858e07d023 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -6557,9 +6557,11 @@ sub process {
>  					$specifier = $1;
>  					$extension = $2;
>  					$qualifier = $3;
> -					if ($extension !~ /[SsBKRraEehMmIiUDdgVCbGNOxtf]/ ||
> +					if ($extension !~ /[4SsBKRraEehMmIiUDdgVCbGNOxtf]/ ||
>  					    ($extension eq "f" &&
> -					     defined $qualifier && $qualifier !~ /^w/)) {
> +					     defined $qualifier && $qualifier !~ /^w/) ||
> +					    ($extension eq "4" &&
> +					     defined $qualifier && $qualifier !~ /^cc/)) {
>  						$bad_specifier = $specifier;
>  						last;
>  					}
> -- 
> 2.29.2
>
Sakari Ailus Feb. 15, 2021, 1:56 p.m. UTC | #2 
Hi Andy,

On Mon, Feb 15, 2021 at 03:31:29PM +0200, Andy Shevchenko wrote:
> On Mon, Feb 15, 2021 at 01:40:28PM +0200, Sakari Ailus wrote:
> > Add a printk modifier %p4cc (for pixel format) for printing V4L2 and DRM
> > pixel formats denoted by fourccs. The fourcc encoding is the same for both
> > so the same implementation can be used.
> 
> This version I almost like, feel free to add
> Reviewed-by: From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> after considering addressing below nit-picks.
> 
> > Suggested-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > Reviewed-by: Petr Mladek <pmladek@suse.com>
> > Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> > ---
> >  Documentation/core-api/printk-formats.rst | 16 ++++++++++
> >  lib/test_printf.c                         | 17 ++++++++++
> >  lib/vsprintf.c                            | 39 +++++++++++++++++++++++
> >  scripts/checkpatch.pl                     |  6 ++--
> >  4 files changed, 76 insertions(+), 2 deletions(-)
> > 
> > diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
> > index 160e710d992f..da2aa065dc42 100644
> > --- a/Documentation/core-api/printk-formats.rst
> > +++ b/Documentation/core-api/printk-formats.rst
> > @@ -567,6 +567,22 @@ For printing netdev_features_t.
> >  
> >  Passed by reference.
> >  
> > +V4L2 and DRM FourCC code (pixel format)
> > +---------------------------------------
> > +
> > +::
> > +
> > +	%p4cc
> > +
> > +Print a FourCC code used by V4L2 or DRM, including format endianness and
> > +its numerical value as hexadecimal.
> > +
> > +Passed by reference.
> > +
> > +Examples::
> > +
> > +	%p4cc	BG12 little-endian (0x32314742)
> 
> No examples with spaces / non-printable / non-ascii characters

I can sure add an example that has a space. But do you think I really
should add an example where invalid information is being printed?

> 
> > +
> >  Thanks
> >  ======
> >  
> > diff --git a/lib/test_printf.c b/lib/test_printf.c
> > index 7d60f24240a4..9848510a2786 100644
> > --- a/lib/test_printf.c
> > +++ b/lib/test_printf.c
> > @@ -647,6 +647,22 @@ static void __init fwnode_pointer(void)
> >  	software_node_unregister_nodes(softnodes);
> >  }
> >  
> > +static void __init fourcc_pointer(void)
> > +{
> > +	struct {
> > +		u32 code;
> > +		char *str;
> > +	} const try[] = {
> > +		{ 0x3231564e, "NV12 little-endian (0x3231564e)", },
> > +		{ 0xb231564e, "NV12 big-endian (0xb231564e)", },
> > +		{ 0x10111213, ".... little-endian (0x10111213)", },
> > +	};
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(try); i++)
> > +		test(try[i].str, "%p4cc", &try[i].code);
> > +}
> > +
> >  static void __init
> >  errptr(void)
> >  {
> > @@ -692,6 +708,7 @@ test_pointer(void)
> >  	flags();
> >  	errptr();
> >  	fwnode_pointer();
> > +	fourcc_pointer();
> >  }
> >  
> >  static void __init selftest(void)
> > diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> > index 3b53c73580c5..432b5a2d1e90 100644
> > --- a/lib/vsprintf.c
> > +++ b/lib/vsprintf.c
> > @@ -1733,6 +1733,42 @@ char *netdev_bits(char *buf, char *end, const void *addr,
> >  	return special_hex_number(buf, end, num, size);
> >  }
> >  
> > +static noinline_for_stack
> > +char *fourcc_string(char *buf, char *end, const u32 *fourcc,
> > +		    struct printf_spec spec, const char *fmt)
> > +{
> > +	char output[sizeof("1234 little-endian (0x01234567)")];
> 
> 1234 -> ABCD ? (Or XY12 to be closer to the reality)

I count in numbers... albeit the hexadecimal number there starts from zero.

I guess both would work though.

0123 would be consistent.
Andy Shevchenko Feb. 15, 2021, 3:54 p.m. UTC | #3 
On Mon, Feb 15, 2021 at 03:56:50PM +0200, Sakari Ailus wrote:
> On Mon, Feb 15, 2021 at 03:31:29PM +0200, Andy Shevchenko wrote:
> > On Mon, Feb 15, 2021 at 01:40:28PM +0200, Sakari Ailus wrote:
> > > Add a printk modifier %p4cc (for pixel format) for printing V4L2 and DRM
> > > pixel formats denoted by fourccs. The fourcc encoding is the same for both
> > > so the same implementation can be used.
> > 
> > This version I almost like, feel free to add
> > Reviewed-by: From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > after considering addressing below nit-picks.

> > > +Examples::
> > > +
> > > +	%p4cc	BG12 little-endian (0x32314742)
> > 
> > No examples with spaces / non-printable / non-ascii characters
> 
> I can sure add an example that has a space. But do you think I really
> should add an example where invalid information is being printed?

I think you have to provide better coverage of what user can get out of this.
Perhaps one example with space and non-printable character is enough.

> > > +	char output[sizeof("1234 little-endian (0x01234567)")];
> > 
> > 1234 -> ABCD ? (Or XY12 to be closer to the reality)
> 
> I count in numbers... albeit the hexadecimal number there starts from zero.
> 
> I guess both would work though.
> 
> 0123 would be consistent.

Since letters can be printed the above is confusing a bit. I think XY12 is
closer to the reality than 0123.
Petr Mladek Feb. 15, 2021, 4:51 p.m. UTC | #4 
On Mon 2021-02-15 17:54:47, Andy Shevchenko wrote:
> On Mon, Feb 15, 2021 at 03:56:50PM +0200, Sakari Ailus wrote:
> > On Mon, Feb 15, 2021 at 03:31:29PM +0200, Andy Shevchenko wrote:
> > > On Mon, Feb 15, 2021 at 01:40:28PM +0200, Sakari Ailus wrote:
> > > > Add a printk modifier %p4cc (for pixel format) for printing V4L2 and DRM
> > > > pixel formats denoted by fourccs. The fourcc encoding is the same for both
> > > > so the same implementation can be used.
> > > 
> > > This version I almost like, feel free to add
> > > Reviewed-by: From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > > after considering addressing below nit-picks.
> 
> > > > +Examples::
> > > > +
> > > > +	%p4cc	BG12 little-endian (0x32314742)
> > > 
> > > No examples with spaces / non-printable / non-ascii characters
> > 
> > I can sure add an example that has a space. But do you think I really
> > should add an example where invalid information is being printed?
> 
> I think you have to provide better coverage of what user can get out of this.
> Perhaps one example with space and non-printable character is enough.
> 
> > > > +	char output[sizeof("1234 little-endian (0x01234567)")];
> > > 
> > > 1234 -> ABCD ? (Or XY12 to be closer to the reality)
> > 
> > I count in numbers... albeit the hexadecimal number there starts from zero.
> > 
> > I guess both would work though.
> > 
> > 0123 would be consistent.
> 
> Since letters can be printed the above is confusing a bit. I think XY12 is
> closer to the reality than 0123.

Ailus, are you going to send v8 with the two small changes? I mean a
selftest with the space and the above sample code.

Anyway, feel free to add:

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr
Sakari Ailus Feb. 15, 2021, 5:21 p.m. UTC | #5 
Hi Petr,

On Mon, Feb 15, 2021 at 05:51:40PM +0100, Petr Mladek wrote:
> On Mon 2021-02-15 17:54:47, Andy Shevchenko wrote:
> > On Mon, Feb 15, 2021 at 03:56:50PM +0200, Sakari Ailus wrote:
> > > On Mon, Feb 15, 2021 at 03:31:29PM +0200, Andy Shevchenko wrote:
> > > > On Mon, Feb 15, 2021 at 01:40:28PM +0200, Sakari Ailus wrote:
> > > > > Add a printk modifier %p4cc (for pixel format) for printing V4L2 and DRM
> > > > > pixel formats denoted by fourccs. The fourcc encoding is the same for both
> > > > > so the same implementation can be used.
> > > > 
> > > > This version I almost like, feel free to add
> > > > Reviewed-by: From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > > > after considering addressing below nit-picks.
> > 
> > > > > +Examples::
> > > > > +
> > > > > +	%p4cc	BG12 little-endian (0x32314742)
> > > > 
> > > > No examples with spaces / non-printable / non-ascii characters
> > > 
> > > I can sure add an example that has a space. But do you think I really
> > > should add an example where invalid information is being printed?
> > 
> > I think you have to provide better coverage of what user can get out of this.
> > Perhaps one example with space and non-printable character is enough.
> > 
> > > > > +	char output[sizeof("1234 little-endian (0x01234567)")];
> > > > 
> > > > 1234 -> ABCD ? (Or XY12 to be closer to the reality)
> > > 
> > > I count in numbers... albeit the hexadecimal number there starts from zero.
> > > 
> > > I guess both would work though.
> > > 
> > > 0123 would be consistent.
> > 
> > Since letters can be printed the above is confusing a bit. I think XY12 is
> > closer to the reality than 0123.
> 
> Ailus, are you going to send v8 with the two small changes? I mean a
> selftest with the space and the above sample code.

Yes, and a few more examples.

> 
> Anyway, feel free to add:
> 
> Reviewed-by: Petr Mladek <pmladek@suse.com>

Thank you.

It'd be great if we could merge this through the printk tree. Acks are
needed from the DRM people first.
diff mbox series

Patch

diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index 160e710d992f..da2aa065dc42 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -567,6 +567,22 @@  For printing netdev_features_t.
 
 Passed by reference.
 
+V4L2 and DRM FourCC code (pixel format)
+---------------------------------------
+
+::
+
+	%p4cc
+
+Print a FourCC code used by V4L2 or DRM, including format endianness and
+its numerical value as hexadecimal.
+
+Passed by reference.
+
+Examples::
+
+	%p4cc	BG12 little-endian (0x32314742)
+
 Thanks
 ======
 
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 7d60f24240a4..9848510a2786 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -647,6 +647,22 @@  static void __init fwnode_pointer(void)
 	software_node_unregister_nodes(softnodes);
 }
 
+static void __init fourcc_pointer(void)
+{
+	struct {
+		u32 code;
+		char *str;
+	} const try[] = {
+		{ 0x3231564e, "NV12 little-endian (0x3231564e)", },
+		{ 0xb231564e, "NV12 big-endian (0xb231564e)", },
+		{ 0x10111213, ".... little-endian (0x10111213)", },
+	};
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(try); i++)
+		test(try[i].str, "%p4cc", &try[i].code);
+}
+
 static void __init
 errptr(void)
 {
@@ -692,6 +708,7 @@  test_pointer(void)
 	flags();
 	errptr();
 	fwnode_pointer();
+	fourcc_pointer();
 }
 
 static void __init selftest(void)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 3b53c73580c5..432b5a2d1e90 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1733,6 +1733,42 @@  char *netdev_bits(char *buf, char *end, const void *addr,
 	return special_hex_number(buf, end, num, size);
 }
 
+static noinline_for_stack
+char *fourcc_string(char *buf, char *end, const u32 *fourcc,
+		    struct printf_spec spec, const char *fmt)
+{
+	char output[sizeof("1234 little-endian (0x01234567)")];
+	char *p = output;
+	unsigned int i;
+	u32 val;
+
+	if (fmt[1] != 'c' || fmt[2] != 'c')
+		return error_string(buf, end, "(%p4?)", spec);
+
+	if (check_pointer(&buf, end, fourcc, spec))
+		return buf;
+
+	val = *fourcc & ~BIT(31);
+
+	for (i = 0; i < sizeof(*fourcc); i++) {
+		unsigned char c = val >> (i * 8);
+
+		/* Print non-control ASCII characters as-is, dot otherwise */
+		*p++ = isascii(c) && isprint(c) ? c : '.';
+	}
+
+	strcpy(p, *fourcc & BIT(31) ? " big-endian" : " little-endian");
+	p += strlen(p);
+
+	*p++ = ' ';
+	*p++ = '(';
+	p = special_hex_number(p, output + sizeof(output) - 2, *fourcc, sizeof(u32));
+	*p++ = ')';
+	*p = '\0';
+
+	return string(buf, end, output, spec);
+}
+
 static noinline_for_stack
 char *address_val(char *buf, char *end, const void *addr,
 		  struct printf_spec spec, const char *fmt)
@@ -2162,6 +2198,7 @@  char *fwnode_string(char *buf, char *end, struct fwnode_handle *fwnode,
  *       correctness of the format string and va_list arguments.
  * - 'K' For a kernel pointer that should be hidden from unprivileged users
  * - 'NF' For a netdev_features_t
+ * - '4cc' V4L2 or DRM FourCC code, with endianness and raw numerical value.
  * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with
  *            a certain separator (' ' by default):
  *              C colon
@@ -2259,6 +2296,8 @@  char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 		return restricted_pointer(buf, end, ptr, spec);
 	case 'N':
 		return netdev_bits(buf, end, ptr, spec, fmt);
+	case '4':
+		return fourcc_string(buf, end, ptr, spec, fmt);
 	case 'a':
 		return address_val(buf, end, ptr, spec, fmt);
 	case 'd':
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 92e888ed939f..79858e07d023 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6557,9 +6557,11 @@  sub process {
 					$specifier = $1;
 					$extension = $2;
 					$qualifier = $3;
-					if ($extension !~ /[SsBKRraEehMmIiUDdgVCbGNOxtf]/ ||
+					if ($extension !~ /[4SsBKRraEehMmIiUDdgVCbGNOxtf]/ ||
 					    ($extension eq "f" &&
-					     defined $qualifier && $qualifier !~ /^w/)) {
+					     defined $qualifier && $qualifier !~ /^w/) ||
+					    ($extension eq "4" &&
+					     defined $qualifier && $qualifier !~ /^cc/)) {
 						$bad_specifier = $specifier;
 						last;
 					}