Re: [PATCH v3 21/24] drm/rockchip: dw-mipi-dsi: defer probe if panel is not loaded

On Tue, 31 Jan 2017 14:21:17 -0500, Sean Paul wrote:

On Sun, Jan 29, 2017 at 01:24:41PM +0000, John Keeping wrote:

quoted

This ensures that the output resolution is known before fbcon loads.

Signed-off-by: John Keeping <redacted>
---
Unchanged in v3
Unchanged in v2

 drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
index f5b15377ef85..5bad92e2370e 100644
--- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c

@@ -1176,10 +1176,17 @@ static int dw_mipi_dsi_bind(struct device *dev, struct device *master,
 
 	dsi->dsi_host.ops = &dw_mipi_dsi_host_ops;
 	dsi->dsi_host.dev = dev;
-	return mipi_dsi_host_register(&dsi->dsi_host);
+	ret = mipi_dsi_host_register(&dsi->dsi_host);
+	if (!ret && !dsi->panel) {
+		mipi_dsi_host_unregister(&dsi->dsi_host);
+		drm_encoder_cleanup(&dsi->encoder);
+		drm_connector_cleanup(&dsi->connector);  

Move the host registration up before dw_mipi_dsi_register() to avoid
having to clean up the encoder and connector?

No, mipi_dsi_host_register() has to be called after the connector is
registered because it is likely to result in a call to
dw_mipi_dsi_host_attach() which attaches a panel to the connector.

quoted

+		ret = -EPROBE_DEFER;
+	}
 
 err_pllref:
-	clk_disable_unprepare(dsi->pllref_clk);
+	if (ret)  

I personally think it's cleaner to explicitly goto in the error conditional (or
in this case, the defer conditional) and have a return 0; right before the err_*
labels. Then you don't need to worry about a) checking ret in all of your
cleanups and b) someone adding code above the labels that you don't intend to
run.

Agreed.  I'll change this to use a goto if we hit the EPROBE_DEFER case
and keep all the cleanup together.

quoted

+		clk_disable_unprepare(dsi->pllref_clk);
 	return ret;
 }

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