On Mon, Oct 27, 2014 at 11:26:30PM +0100, Daniel Vetter wrote:
> Looking at the of_drm_find_panel function I actually wonder how that
> works - the drm_panel doesn't really need to stick around afaics.
> After all panel_list is global so some other driver can unload.
> Russell's of support for possible_crtcs code works differently since
> it only looks at per-drm_device lists.
> 
> This bridge code here though suffers from the same. So to me this
> looks rather fishy.
> 
> It doesn't help that we have drm_of.[hc] around but not all the of
> code is in there. Adding Russell too.

I rather dropped the ball with imx-drm when things became difficult with
asking Greg to pull my git tree - and as a result, I decided that I would
no longer be helping with patch submission for imx-drm, nor trying to get
it out of the staging tree anymore.

I do still have the patch (dated from July) in my git tree which adds it
to imx-drm - see below.  Rebased to 3.18-rc2 today.

I also have a patch (from April) which creates a generic OF DDC connector
helper, but that remains unfinished, in the sense that it lives beside
imx-drm, pulling the DDC specific code out of imx-hdmi and imx-tve, even
though there's nothing imx-drm specific about it.

8<====
From: Russell King <rmk+ker...@arm.linux.org.uk>
Subject: [PATCH] imx-drm: convert imx-drm to use the generic DRM OF helper

Use the generic DRM OF helper to locate the possible CRTCs for the
encoder, thereby shrinking the imx-drm driver some more.

Acked-by: Philipp Zabel <p.zabel at pengutronix.de>
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
---
 drivers/staging/imx-drm/imx-drm-core.c | 72 ++++++----------------------------
 1 file changed, 13 insertions(+), 59 deletions(-)

diff --git a/drivers/staging/imx-drm/imx-drm-core.c 
b/drivers/staging/imx-drm/imx-drm-core.c
index 9cb222e2996f..5e2c1f4b9165 100644
--- a/drivers/staging/imx-drm/imx-drm-core.c
+++ b/drivers/staging/imx-drm/imx-drm-core.c
@@ -24,6 +24,7 @@
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_gem_cma_helper.h>
 #include <drm/drm_fb_cma_helper.h>
+#include <drm/drm_of.h>

 #include "imx-drm.h"

@@ -47,7 +48,6 @@ struct imx_drm_crtc {
        struct drm_crtc                         *crtc;
        int                                     pipe;
        struct imx_drm_crtc_helper_funcs        imx_drm_helper_funcs;
-       struct device_node                      *port;
 };

 static int legacyfb_depth = 16;
@@ -366,9 +366,10 @@ int imx_drm_add_crtc(struct drm_device *drm, struct 
drm_crtc *crtc,

        imx_drm_crtc->imx_drm_helper_funcs = *imx_drm_helper_funcs;
        imx_drm_crtc->pipe = imxdrm->pipes++;
-       imx_drm_crtc->port = port;
        imx_drm_crtc->crtc = crtc;

+       crtc->port = port;
+
        imxdrm->crtc[imx_drm_crtc->pipe] = imx_drm_crtc;

        *new_crtc = imx_drm_crtc;
@@ -409,34 +410,6 @@ int imx_drm_remove_crtc(struct imx_drm_crtc *imx_drm_crtc)
 }
 EXPORT_SYMBOL_GPL(imx_drm_remove_crtc);

-/*
- * Find the DRM CRTC possible mask for the connected endpoint.
- *
- * The encoder possible masks are defined by their position in the
- * mode_config crtc_list.  This means that CRTCs must not be added
- * or removed once the DRM device has been fully initialised.
- */
-static uint32_t imx_drm_find_crtc_mask(struct imx_drm_device *imxdrm,
-       struct device_node *endpoint)
-{
-       struct device_node *port;
-       unsigned i;
-
-       port = of_graph_get_remote_port(endpoint);
-       if (!port)
-               return 0;
-       of_node_put(port);
-
-       for (i = 0; i < MAX_CRTC; i++) {
-               struct imx_drm_crtc *imx_drm_crtc = imxdrm->crtc[i];
-
-               if (imx_drm_crtc && imx_drm_crtc->port == port)
-                       return drm_crtc_mask(imx_drm_crtc->crtc);
-       }
-
-       return 0;
-}
-
 static struct device_node *imx_drm_of_get_next_endpoint(
                const struct device_node *parent, struct device_node *prev)
 {
@@ -449,35 +422,16 @@ static struct device_node *imx_drm_of_get_next_endpoint(
 int imx_drm_encoder_parse_of(struct drm_device *drm,
        struct drm_encoder *encoder, struct device_node *np)
 {
-       struct imx_drm_device *imxdrm = drm->dev_private;
-       struct device_node *ep = NULL;
-       uint32_t crtc_mask = 0;
-       int i;
+       uint32_t crtc_mask = drm_of_find_possible_crtcs(drm, np);

-       for (i = 0; ; i++) {
-               u32 mask;
-
-               ep = imx_drm_of_get_next_endpoint(np, ep);
-               if (!ep)
-                       break;
-
-               mask = imx_drm_find_crtc_mask(imxdrm, ep);
-
-               /*
-                * If we failed to find the CRTC(s) which this encoder is
-                * supposed to be connected to, it's because the CRTC has
-                * not been registered yet.  Defer probing, and hope that
-                * the required CRTC is added later.
-                */
-               if (mask == 0)
-                       return -EPROBE_DEFER;
-
-               crtc_mask |= mask;
-       }
-
-       of_node_put(ep);
-       if (i == 0)
-               return -ENOENT;
+       /*
+        * If we failed to find the CRTC(s) which this encoder is
+        * supposed to be connected to, it's because the CRTC has
+        * not been registered yet.  Defer probing, and hope that
+        * the required CRTC is added later.
+        */
+       if (crtc_mask == 0)
+               return -EPROBE_DEFER;

        encoder->possible_crtcs = crtc_mask;

@@ -511,7 +465,7 @@ int imx_drm_encoder_get_mux_id(struct device_node *node,

                port = of_graph_get_remote_port(ep);
                of_node_put(port);
-               if (port == imx_crtc->port) {
+               if (port == imx_crtc->crtc->port) {
                        ret = of_graph_parse_endpoint(ep, &endpoint);
                        return ret ? ret : endpoint.port;
                }
-- 
1.8.3.1



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