Re: [PATCH v2 03/23] OMAPDSS: output: Add set/unset device ops for omap_dss_output

[Tomi Valkeinen <tomi.valkeinen@ti.com>]

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On Thu, 2012-08-30 at 17:10 +0530, Archit Taneja wrote:
> An output entity represented by the struct omap_dss_output connects to a
> omap_dss_device entity. Add functions to set or unset an output's device. This
> is similar to how managers and devices were connected previously. An output can
> connect to a device without being connected to a manager. However, the output
> needs to eventually connect to a manager so that the connected panel can be
> enabled.
> 
> Keep the omap_overlay_manager pointer in omap_dss_device for now to prevent
> breaking things. This will be removed later when outputs are supported
> completely.
> 
> Signed-off-by: Archit Taneja <archit@ti.com>
> ---
>  drivers/video/omap2/dss/output.c |   67 ++++++++++++++++++++++++++++++++++++++
>  include/video/omapdss.h          |    5 +++
>  2 files changed, 72 insertions(+)
> 
> diff --git a/drivers/video/omap2/dss/output.c b/drivers/video/omap2/dss/output.c
> index 7d81be5..abc3aa2 100644
> --- a/drivers/video/omap2/dss/output.c
> +++ b/drivers/video/omap2/dss/output.c
> @@ -24,9 +24,76 @@
>  #include "dss.h"
>  
>  static LIST_HEAD(output_list);
> +static DEFINE_MUTEX(output_lock);
> +
> +static int dss_output_set_device(struct omap_dss_output *out,
> +		struct omap_dss_device *dssdev)
> +{
> +	int r;
> +
> +	mutex_lock(&output_lock);
> +
> +	if (out->device) {
> +		DSSERR("output already has device %s connected to it\n",
> +			out->device->name);
> +		r = -EINVAL;
> +		goto err;
> +	}
> +
> +	if (out->type != dssdev->type) {
> +		DSSERR("output type and display type don't match\n");
> +		r = -EINVAL;
> +		goto err;
> +	}
> +
> +	out->device = dssdev;
> +	dssdev->output = out;
> +
> +	mutex_unlock(&output_lock);
> +
> +	return 0;
> +err:
> +	mutex_unlock(&output_lock);
> +
> +	return r;
> +}
> +
> +static int dss_output_unset_device(struct omap_dss_output *out)
> +{
> +	int r;
> +
> +	mutex_lock(&output_lock);
> +
> +	if (!out->device) {
> +		DSSERR("output doesn't have a device connected to it\n");
> +		r = -EINVAL;
> +		goto err;
> +	}
> +
> +	if (out->device->state != OMAP_DSS_DISPLAY_DISABLED) {
> +		DSSERR("device %s is not disabled, cannot unset device\n",
> +				out->device->name);
> +		r = -EINVAL;
> +		goto err;
> +	}
> +
> +	out->device->output = NULL;
> +	out->device = NULL;
> +
> +	mutex_unlock(&output_lock);
> +
> +	return 0;
> +err:
> +	mutex_unlock(&output_lock);
> +
> +	return r;
> +}
>  
>  void dss_register_output(struct omap_dss_output *out)
>  {
> +	out->set_device = &dss_output_set_device;
> +	out->unset_device = &dss_output_unset_device;
> +
>  	list_add_tail(&out->list, &output_list);
>  }

I don't think there's need for this indirection. We should use function
pointers only when the func pointer may lead to different functions.
Here we'll always have just one function, dss_output_set_device. We can
as well call the function directly.

I know we have similar func pointers for ovls/mgrs currently, but I
don't think they are good either. They are a relic from the time we
supported "virtual" overlays and managers, and thus could have different
implementations for the operations.

 Tomi


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