Re: [PATCH 11/24] drm/omap: Add kernel parameter to specify the desired display order

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomi,

Thank you for the patch.

On Monday, 12 February 2018 11:44:41 EET Tomi Valkeinen wrote:
> From: Peter Ujfalusi <peter.ujfalusi@ti.com>
> 
> omapdrm.displays (int array) can be used to reorder the displays by id if
> needed. It can be also used to disable display.
> 
> If the board have two active displays:
> 0 - LCD
> 1 - HDMI
> then:
> omapdrm.displays=0,1 - represents the original order (LCD, HDMI)
> omapdrm.displays=1,0 - represents reverse order (HDMI, LCD)
> omapdrm.displays=0 - only the LCD is enabled
> omapdrm.displays=1 - only the HDMI is enabled
> omapdrm.displays=-1 - disable all displays

What's the use case for this ?

> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> ---
>  drivers/gpu/drm/omapdrm/omap_drv.c | 55 ++++++++++++++++++++++++++++++++---
>  1 file changed, 51 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c
> b/drivers/gpu/drm/omapdrm/omap_drv.c index 877c3749f69b..5a27a47b628e
> 100644
> --- a/drivers/gpu/drm/omapdrm/omap_drv.c
> +++ b/drivers/gpu/drm/omapdrm/omap_drv.c
> @@ -34,6 +34,14 @@
>  #define DRIVER_MINOR		0
>  #define DRIVER_PATCHLEVEL	0
> 
> +#define MAX_NR_DISPLAYS		8
> +static int display_order[MAX_NR_DISPLAYS];
> +static int display_order_nelm;
> +module_param_array_named(displays, display_order, int, &display_order_nelm,
> +			 0444);
> +MODULE_PARM_DESC(displays,
> +		 "ID array to specify the order of the active displays");
> +
>  /*
>   * mode config funcs
>   */
> @@ -182,12 +190,21 @@ static int omap_compare_dssdevs(const void *a, const
> void *b) static void omap_collect_dssdevs(struct drm_device *ddev)
>  {
>  	struct omap_drm_private *priv = ddev->dev_private;
> +	struct omap_dss_device *dssdevs[ARRAY_SIZE(priv->dssdevs)];
>  	struct omap_dss_device *dssdev = NULL;
> +	int num_dssdevs = 0;

unsigned int.

> +	unsigned long dssdev_mask = 0;
> +	int i;

unsigned int.

> +
> +	/* No displays should be enabled */
> +	if (display_order_nelm == 1 && display_order[0] < 0)
> +		return;
> 
>  	for_each_dss_dev(dssdev) {
>  		omap_dss_get_device(dssdev);
> -		priv->dssdevs[priv->num_dssdevs++] = dssdev;
> -		if (priv->num_dssdevs == ARRAY_SIZE(priv->dssdevs)) {
> +		set_bit(num_dssdevs, &dssdev_mask);
> +		dssdevs[num_dssdevs++] = dssdev;
> +		if (num_dssdevs == ARRAY_SIZE(dssdevs)) {
>  			/* To balance the 'for_each_dss_dev' loop */
>  			omap_dss_put_device(dssdev);
>  			break;
> @@ -195,8 +212,38 @@ static void omap_collect_dssdevs(struct drm_device
> *ddev) }
> 
>  	/* Sort the list by DT aliases */
> -	sort(priv->dssdevs, priv->num_dssdevs, sizeof(priv->dssdevs[0]),
> -	     omap_compare_dssdevs, NULL);
> +	sort(dssdevs, num_dssdevs, sizeof(dssdevs[0]), omap_compare_dssdevs,
> +	     NULL);
> +
> +	/* Do ordering based on the display_order parameter array */
> +	for (i = 0; i < display_order_nelm; i++) {
> +		int old_index = display_order[i];
> +
> +		if ((old_index >= 0 && old_index < num_dssdevs) &&

No need for the inner parentheses.

> +		    (dssdev_mask & BIT(old_index))) {
> +			priv->dssdevs[priv->num_dssdevs++] = dssdevs[old_index];
> +			clear_bit(old_index, &dssdev_mask);
> +		} else {
> +			dev_err(ddev->dev,
> +				"Ignoring invalid displays module parameter\n");
> +			priv->num_dssdevs = 0;
> +			break;
> +		}
> +	}
> +
> +	/* if the target list is empty, copy the collected dssdevs, if any */
> +	if (priv->num_dssdevs == 0) {
> +		for (i = 0; i < num_dssdevs; i++)
> +			priv->dssdevs[i] = dssdevs[i];
> +
> +		priv->num_dssdevs = num_dssdevs;
> +	} else {
> +		u32 idx;
> +
> +		/* check if we have dssdev which is not carried over */
> +		for_each_set_bit(idx, &dssdev_mask, ARRAY_SIZE(dssdevs))
> +			omap_dss_put_device(dssdevs[idx]);
> +	}
>  }
> 
>  static int omap_connect_dssdevs(struct drm_device *ddev)

-- 
Regards,

Laurent Pinchart

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