Re: [PATCH v3 1/2] drm: Enhance EDID quirks to explicitly set a mode

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

Hi, please find some review comments inline.

BR,
Jani.

On Sat, 23 Mar 2013, Dylan Semler <dylan.semler@gmail.com> wrote:
> There is at least one monitor that doesn't report its native resolution
> in its EDID block.  This enhancement extends the EDID quirk logic to
> make monitors like this "just work".
>
> This patch sets up a new quirk list where monitors' correct width,
> height, refresh rate, and reduced blanking parameters are specified.
> When a matching monitor is attached the full mode is calculated with
> drm_cvt_mode() and added to the connector.  The DRM_MODE_TYPE_PREFERRED
> bit is set on the new mode and unset from all other modes.
>
> The patch also defines a new quirk bit: EDID_QUIRK_FORCE_MODE.  This
> bit needs to be set for the new quirk list discribed above to be
> checked.
>
> Signed-off-by: Dylan Semler <dylan.semler@gmail.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 78 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index c194f4e..38b8641 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -68,6 +68,8 @@
>  #define EDID_QUIRK_DETAILED_SYNC_PP		(1 << 6)
>  /* Force reduced-blanking timings for detailed modes */
>  #define EDID_QUIRK_FORCE_REDUCED_BLANKING	(1 << 7)
> +/* Force specific mode for monitors that don't report correct EDIDs */
> +#define EDID_QUIRK_FORCE_MODE			(1 << 8)
>  
>  struct detailed_mode_closure {
>  	struct drm_connector *connector;
> @@ -127,6 +129,16 @@ static struct edid_quirk {
>  	{ "VSC", 5020, EDID_QUIRK_FORCE_REDUCED_BLANKING },
>  };
>  
> +static struct edid_quirk_force_mode {
> +	char vendor[4];
> +	int product_id;
> +	int hdisplay;
> +	int vdisplay;
> +	int vrefresh;
> +	bool reduced;
> +} edid_quirk_force_mode_list[] = {
> +};
> +
>  /*
>   * Autogenerated from the DMT spec.
>   * This table is copied from xfree86/modes/xf86EdidModes.c.
> @@ -2219,6 +2231,70 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
>  	return closure.modes;
>  }
>  
> +/* Add an explicit mode based on a quirk
> + */
> +static int
> +do_force_quirk_modes(struct drm_connector *connector, int hdisplay,
> +		     int vdisplay, int vrefresh, bool reduced)

Nitpick: This adds one mode, not many _modes_.

> +{
> +	struct drm_display_mode *mode, *t, *cur_mode;
> +	struct drm_device *dev = connector->dev;
> +	int num_modes = 0;
> +
> +	/* sanity check display parameters */
> +	if (hdisplay < 0)
> +		return 0;
> +	if (vdisplay < 0)
> +		return 0;
> +	if (vrefresh < 0)
> +		return 0;
> +
> +	/* loop through the probed modes and clear the preferred bit */
> +	list_for_each_entry_safe(cur_mode, t, &connector->probed_modes, head)
> +		cur_mode->type &= ~DRM_MODE_TYPE_PREFERRED;

You're not deleting entries, so list_for_each_entry() would suffice,
getting rid of the temp variable.

> +
> +	mode = drm_cvt_mode(dev, hdisplay, vdisplay, vrefresh, reduced, 0, 0);

You could

	if (!mode)
		return 0;

here and get rid of the num_modes variable.

> +
> +	if (mode) {
> +		mode->type |= DRM_MODE_TYPE_PREFERRED;
> +		drm_mode_probed_add(connector, mode);
> +		num_modes++;
> +	}
> +	return num_modes;
> +}
> +
> +/*
> + * add_force_quirk_modes - Add modes based on monitor's EDID quirks
> + * @connector: attached connector
> + * @edid: EDID block to scan
> + * @quirks: quirks to apply
> + *
> + * At least one monitor doesn't report its native resolution in its EDID block.
> + * Here we add the native mode according to this quirk
> + */
> +static int
> +add_force_quirk_modes(struct drm_connector *connector, struct edid *edid,
> +		      u32 quirks)
> +{
> +	struct edid_quirk_force_mode *quirk_mode;
> +	int i, num_modes = 0;
> +
> +	for (i = 0; i < ARRAY_SIZE(edid_quirk_force_mode_list); i++) {
> +		quirk_mode = &edid_quirk_force_mode_list[i];
> +
> +		if (edid_vendor(edid, quirk_mode->vendor) &&
> +		    (EDID_PRODUCT_ID(edid) == quirk_mode->product_id)) {
> +			num_modes = do_force_quirk_modes(connector,
> +					quirk_mode->hdisplay,
> +					quirk_mode->vdisplay,
> +					quirk_mode->vrefresh,
> +					quirk_mode->reduced);

I was wondering why you don't bail out here. Maybe you want to be able
to add more than one quirk mode? In that case you should +=, not = the
num_modes.

(Note that then do_force_quirk_modes makes the last one in the array the
preferred mode, clearing the DRM_MODE_TYPE_PREFERRED from the previously
added quirk modes.)

> +		}
> +	}
> +	return num_modes;
> +
> +}
> +
>  #define HDMI_IDENTIFIER 0x000C03
>  #define AUDIO_BLOCK	0x01
>  #define VIDEO_BLOCK     0x02
> @@ -2803,6 +2879,8 @@ int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid)
>  
>  	if (quirks & (EDID_QUIRK_PREFER_LARGE_60 | EDID_QUIRK_PREFER_LARGE_75))
>  		edid_fixup_preferred(connector, quirks);
> +	if (quirks & EDID_QUIRK_FORCE_MODE)
> +		num_modes += add_force_quirk_modes(connector, edid, quirks);

You don't use quirks within add_force_quirk_modes() for anything.

>  
>  	drm_add_display_info(edid, &connector->display_info);
>  
> -- 
> 1.7.11.7
>
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