imx-drm: imx-drm-core: sanitise imx_drm_encoder_get_mux_id()

Address the following issues:
- imx_drm_encoder_get_mux_id() searches the CRTC list for the matching
  CRTC, and returns the position within this list as the MUX programming
  value for encoders.  This is sub-optimal for two reasons:
  1. It relies upon the CRTC list not changing during the lifetime of
     the driver.
  2. It is dependent on the initialisation order of the CRTCs.

  We address (1) in this patch, leaving (2) until a better solution can
  be found, as (2) requires larger changes.

- imx_drm_encoder is unused.  Instead, pass the drm_encoder which is
  slightly more useful; all callers pass encoder->crtc as the required
  crtc, so move this inside the function.

Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 6 insertions, 11 deletions

diff --git a/drivers/staging/imx-drm/imx-drm-core.c b/drivers/staging/imx-drm/imx-drm-core.c
index 236ed66f116a..92fde89f58ac 100644
--- a/drivers/staging/imx-drm/imx-drm-core.c
+++ b/drivers/staging/imx-drm/imx-drm-core.c
@@ -53,6 +53,7 @@ struct imx_drm_crtc {
 	struct imx_drm_crtc_helper_funcs	imx_drm_helper_funcs;
 	struct module				*owner;
 	struct crtc_cookie			cookie;
+	int					mux_id;
 };
 
 struct imx_drm_encoder {
@@ -503,7 +504,7 @@ int imx_drm_add_crtc(struct drm_crtc *crtc,
 	imx_drm_crtc->pipe = imxdrm->pipes++;
 	imx_drm_crtc->cookie.cookie = cookie;
 	imx_drm_crtc->cookie.id = id;
-
+	imx_drm_crtc->mux_id = imx_drm_crtc->pipe;
 	imx_drm_crtc->crtc = crtc;
 	imx_drm_crtc->imxdrm = imxdrm;
 
@@ -657,22 +658,16 @@ int imx_drm_encoder_add_possible_crtcs(
 }
 EXPORT_SYMBOL_GPL(imx_drm_encoder_add_possible_crtcs);
 
-int imx_drm_encoder_get_mux_id(struct imx_drm_encoder *imx_drm_encoder,
-		struct drm_crtc *crtc)
+int imx_drm_encoder_get_mux_id(struct drm_encoder *encoder)
 {
 	struct imx_drm_device *imxdrm = __imx_drm_device();
 	struct imx_drm_crtc *imx_crtc;
-	int i = 0;
 
-	list_for_each_entry(imx_crtc, &imxdrm->crtc_list, list) {
-		if (imx_crtc->crtc == crtc)
-			goto found;
-		i++;
-	}
+	list_for_each_entry(imx_crtc, &imxdrm->crtc_list, list)
+		if (imx_crtc->crtc == encoder->crtc)
+			return imx_crtc->mux_id;
 
 	return -EINVAL;
-found:
-	return i;
 }
 EXPORT_SYMBOL_GPL(imx_drm_encoder_get_mux_id);