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

On Friday 31 August 2012 05:33 PM, Tomi Valkeinen wrote:

On Thu, 2012-08-30 at 17:10 +0530, Archit Taneja wrote:

quoted

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 <redacted>
---
  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.

Okay. I understand that. But in general, don't func pointers prevent us 
from exporting more symbols?

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.

Oh okay, I guess you mean the L4/sDMA updates for DSI command mode.

Archit