diff mbox

[05/12] video/hdmi: Don't let the user of this API create invalid infoframes

Message ID 1376500755-30227-6-git-send-email-damien.lespiau@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Lespiau, Damien Aug. 14, 2013, 5:19 p.m. UTC
To set the active aspect ratio value in the AVI infoframe today, you not
only have to set the active_aspect field, but also the active_info_valid
bit. Out of the 1 user of this API, we had 100% misuse, forgetting the
_valid bit. This was fixed in:

  Author: Damien Lespiau <damien.lespiau@intel.com>
  Date:   Tue Aug 6 20:32:17 2013 +0100

      drm: Don't generate invalid AVI infoframes for CEA modes

We can do better and derive the _valid bit from the user wanting to set
the active aspect ratio.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/drm_edid.c | 1 -
 drivers/video/hdmi.c       | 4 +++-
 include/linux/hdmi.h       | 1 -
 3 files changed, 3 insertions(+), 3 deletions(-)

Comments

Thierry Reding Aug. 15, 2013, 2:44 p.m. UTC | #1
On Wed, Aug 14, 2013 at 06:19:08PM +0100, Damien Lespiau wrote:
> To set the active aspect ratio value in the AVI infoframe today, you not
> only have to set the active_aspect field, but also the active_info_valid
> bit. Out of the 1 user of this API, we had 100% misuse, forgetting the
> _valid bit. This was fixed in:
> 
>   Author: Damien Lespiau <damien.lespiau@intel.com>
>   Date:   Tue Aug 6 20:32:17 2013 +0100
> 
>       drm: Don't generate invalid AVI infoframes for CEA modes
> 
> We can do better and derive the _valid bit from the user wanting to set
> the active aspect ratio.
[...]
> diff --git a/drivers/video/hdmi.c b/drivers/video/hdmi.c
[...]
> @@ -96,7 +96,9 @@ ssize_t hdmi_avi_infoframe_pack(struct hdmi_avi_infoframe *frame, void *buffer,
>  
>  	ptr[0] = ((frame->colorspace & 0x3) << 5) | (frame->scan_mode & 0x3);
>  
> -	if (frame->active_info_valid)
> +	/* Data byte 1, bit 4 has to be set if we provide the active format
> +	 * aspect ratio */

Nit: According to the coding style rules this should be:

	/*
	 * Data byte 1, ...
	 * ... ratio.
	 */

> +	if (frame->active_aspect & 0xf)
>  		ptr[0] |= BIT(4);
>  
>  	if (frame->horizontal_bar_valid)
> diff --git a/include/linux/hdmi.h b/include/linux/hdmi.h
> index bc6743e..931474c6 100644
> --- a/include/linux/hdmi.h
> +++ b/include/linux/hdmi.h
> @@ -109,7 +109,6 @@ struct hdmi_avi_infoframe {
>  	unsigned char version;
>  	unsigned char length;
>  	enum hdmi_colorspace colorspace;
> -	bool active_info_valid;

When I initially came up with these data structure I wanted them to
explicitly expose all the fields that CEA/HDMI specifies. The idea was
that a user would actually be allowed to generate invalid infoframes if
they chose to by modifying the hdmi_avi_infoframe structure directly.

Instead I'd prefer to see this handled by some higher level function.

Thierry
diff mbox

Patch

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 2381abd..d76d608 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3259,7 +3259,6 @@  drm_hdmi_avi_infoframe_from_display_mode(struct hdmi_avi_infoframe *frame,
 	frame->video_code = drm_match_cea_mode(mode);
 
 	frame->picture_aspect = HDMI_PICTURE_ASPECT_NONE;
-	frame->active_info_valid = 1;
 	frame->active_aspect = HDMI_ACTIVE_ASPECT_PICTURE;
 
 	return 0;
diff --git a/drivers/video/hdmi.c b/drivers/video/hdmi.c
index 635d569..e36da36 100644
--- a/drivers/video/hdmi.c
+++ b/drivers/video/hdmi.c
@@ -96,7 +96,9 @@  ssize_t hdmi_avi_infoframe_pack(struct hdmi_avi_infoframe *frame, void *buffer,
 
 	ptr[0] = ((frame->colorspace & 0x3) << 5) | (frame->scan_mode & 0x3);
 
-	if (frame->active_info_valid)
+	/* Data byte 1, bit 4 has to be set if we provide the active format
+	 * aspect ratio */
+	if (frame->active_aspect & 0xf)
 		ptr[0] |= BIT(4);
 
 	if (frame->horizontal_bar_valid)
diff --git a/include/linux/hdmi.h b/include/linux/hdmi.h
index bc6743e..931474c6 100644
--- a/include/linux/hdmi.h
+++ b/include/linux/hdmi.h
@@ -109,7 +109,6 @@  struct hdmi_avi_infoframe {
 	unsigned char version;
 	unsigned char length;
 	enum hdmi_colorspace colorspace;
-	bool active_info_valid;
 	bool horizontal_bar_valid;
 	bool vertical_bar_valid;
 	enum hdmi_scan_mode scan_mode;