Re: [PATCH 1/9] drm: Add drm_mode_debug_printmodeline_raw

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 27 Apr 2016, Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
> Purpose is to enable drivers to print out just the mode
> string with their own formatting.

Some alternatives that preserve the use of a single printk(), avoiding
garbled console output due to races (as discussed on intel-gfx in reply
to the cover letter [1]):

1) Simply add a prefix string parameter to use in
   drm_mode_debug_printmodeline(). Really easy and covers most
   needs. Maybe wrap this in a macro to use the caller's function name.

2) Model drm_mode_debug_printmodeline() after drm_ut_debug_printk(),
   adding a mode parameter. Maybe wrap this in a macro to use the
   caller's function name.

3) Add char *drm_mode_line(mode) that kmallocs a mode line string, or a
   drm_mode_line(mode, buf, bufsize) that prints the mode string to a
   statically allocated buffer.

BR,
Jani.


[1] http://mid.gmane.org/87fuu7jp8x.fsf@intel.com

>
> Existing drm_mode_debug_printmodeline calls the new
> helper and the format is unchanged in this patch.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: dri-devel@lists.freedesktop.org
> ---
>  drivers/gpu/drm/drm_modes.c | 29 ++++++++++++++++++++++-------
>  include/drm/drm_modes.h     |  1 +
>  2 files changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
> index 7def3d58da18..fd4795e2c8db 100644
> --- a/drivers/gpu/drm/drm_modes.c
> +++ b/drivers/gpu/drm/drm_modes.c
> @@ -42,6 +42,24 @@
>  #include "drm_crtc_internal.h"
>  
>  /**
> + * drm_mode_debug_printmodeline_raw - print a mode raw string to dmesg
> + * @mode: mode to print
> + *
> + * Describe @mode using DRM_DEBUG without the loglevel, drm prefix and newline.
> + */
> +void drm_mode_debug_printmodeline_raw(const struct drm_display_mode *mode)
> +{
> +	if (drm_debug & DRM_UT_KMS)
> +		printk("%d:\"%s\" %d %d %d %d %d %d %d %d %d %d 0x%x 0x%x",
> +		       mode->base.id, mode->name, mode->vrefresh, mode->clock,
> +		       mode->hdisplay, mode->hsync_start,
> +		       mode->hsync_end, mode->htotal,
> +		       mode->vdisplay, mode->vsync_start,
> +		       mode->vsync_end, mode->vtotal, mode->type, mode->flags);
> +}
> +EXPORT_SYMBOL(drm_mode_debug_printmodeline_raw);
> +
> +/**
>   * drm_mode_debug_printmodeline - print a mode to dmesg
>   * @mode: mode to print
>   *
> @@ -49,13 +67,10 @@
>   */
>  void drm_mode_debug_printmodeline(const struct drm_display_mode *mode)
>  {
> -	DRM_DEBUG_KMS("Modeline %d:\"%s\" %d %d %d %d %d %d %d %d %d %d "
> -			"0x%x 0x%x\n",
> -		mode->base.id, mode->name, mode->vrefresh, mode->clock,
> -		mode->hdisplay, mode->hsync_start,
> -		mode->hsync_end, mode->htotal,
> -		mode->vdisplay, mode->vsync_start,
> -		mode->vsync_end, mode->vtotal, mode->type, mode->flags);
> +	DRM_DEBUG_KMS("Modeline ");
> +	drm_mode_debug_printmodeline_raw(mode);
> +	if (drm_debug & DRM_UT_KMS)
> +		printk("\n");
>  }
>  EXPORT_SYMBOL(drm_mode_debug_printmodeline);
>  
> diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
> index 625966a906f2..9bb0cd06b80e 100644
> --- a/include/drm/drm_modes.h
> +++ b/include/drm/drm_modes.h
> @@ -437,6 +437,7 @@ int drm_mode_convert_umode(struct drm_display_mode *out,
>  			   const struct drm_mode_modeinfo *in);
>  void drm_mode_probed_add(struct drm_connector *connector, struct drm_display_mode *mode);
>  void drm_mode_debug_printmodeline(const struct drm_display_mode *mode);
> +void drm_mode_debug_printmodeline_raw(const struct drm_display_mode *mode);
>  
>  struct drm_display_mode *drm_cvt_mode(struct drm_device *dev,
>  				      int hdisplay, int vdisplay, int vrefresh,

-- 
Jani Nikula, Intel Open Source Technology Center
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