Re: [PATCH v2 1/6] drm: add drm_print_bits

On Tue, Sep 03, 2019 at 12:12:43PM +0200, Gerd Hoffmann wrote:

New helper to print named bits of some value (think flags fields).

Signed-off-by: Gerd Hoffmann kraxel@redhat.com

include/drm/drm_print.h | 3 +++ drivers/gpu/drm/drm_print.c | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+)

diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h index a5d6f2f3e430..8658c1da1c7d 100644 --- a/include/drm/drm_print.h +++ b/include/drm/drm_print.h @@ -88,6 +88,9 @@ __printf(2, 3) void drm_printf(struct drm_printer *p, const char *f, ...); void drm_puts(struct drm_printer *p, const char *str); void drm_print_regset32(struct drm_printer *p, struct debugfs_regset32 *regset); +void drm_print_bits(struct drm_printer *p, unsigned int indent,

•     const char *label, unsigned int value,
  

•     const char *bits[], unsigned int nbits);
  
  

__printf(2, 0) /** diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c index a17c8a14dba4..7f7aba920f51 100644 --- a/drivers/gpu/drm/drm_print.c +++ b/drivers/gpu/drm/drm_print.c @@ -179,6 +179,42 @@ void drm_printf(struct drm_printer *p, const char *f, ...) } EXPORT_SYMBOL(drm_printf);

+/**

• • drm_print_bits - print bits to a &drm_printer stream
• • Print bits (in flag fields for example) in human readable form.
• • @p: the &drm_printer
• • @indent: Tab indentation level (max 5)
• • @label: field label.
• • @value: field value.
• • @bits: Array with bit names.
• • @nbits: bit name array size.
• */

+void drm_print_bits(struct drm_printer *p, unsigned int indent,

•     const char *label, unsigned int value,
  

•     const char *bits[], unsigned int nbits)
  

+{

• bool first = true;
• unsigned int i;
• for (i = 0; i < nbits; i++) {

• if (!(value & (1 << i)))
  

• 	continue;
  

• if (!bits[i])
  

I think this should be a WARN_ON, indicates a programming error?

• 	continue;
  

• if (first) {
  

• 	first = false;
  

• 	drm_printf_indent(p, indent, "%s=%s",
  

• 			  label, bits[i]);
  

Hm, to make this a bit more flexible to use I'd drop the label= printing ...

• } else
  

• 	drm_printf(p, ",%s", bits[i]);
  

• }
• if (!first)

• drm_printf(p, "\n");
  

... and also the newline. Then you could also use this for bit-fields which just a few bits. Also, should we print anything if no bit is set?

If you prefer the label= + \n then pls add that to the kerneldoc, that it prints this as a line of its own. -Daniel

+} +EXPORT_SYMBOL(drm_print_bits);

void drm_dev_printk(const struct device *dev, const char *level, const char *format, ...) { -- 2.18.1