[PATCH] drm/vc4: Fix oops dereferencing DPI's connector since panel_bridge.

From: Eric Anholt
Date: Fri Mar 09 2018 - 18:33:07 EST


In the cleanup, I didn't notice that we needed to dereference the
connector for the bus_format. Fix the regression by looking up the
first (and only) connector attached to us, and assume that its
bus_format is what we want. Some day it would be good to have that
part of display_info attached to the bridge, instead.

Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
Fixes: 7b1298e05310 ("drm/vc4: Switch DPI to using the panel-bridge helper.")
Cc: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
---
drivers/gpu/drm/vc4/vc4_dpi.c | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_dpi.c b/drivers/gpu/drm/vc4/vc4_dpi.c
index 72c9dbd81d7f..88783e143cc2 100644
--- a/drivers/gpu/drm/vc4/vc4_dpi.c
+++ b/drivers/gpu/drm/vc4/vc4_dpi.c
@@ -96,7 +96,6 @@ struct vc4_dpi {
struct platform_device *pdev;

struct drm_encoder *encoder;
- struct drm_connector *connector;

void __iomem *regs;

@@ -164,14 +163,31 @@ static void vc4_dpi_encoder_disable(struct drm_encoder *encoder)

static void vc4_dpi_encoder_enable(struct drm_encoder *encoder)
{
+ struct drm_device *dev = encoder->dev;
struct drm_display_mode *mode = &encoder->crtc->mode;
struct vc4_dpi_encoder *vc4_encoder = to_vc4_dpi_encoder(encoder);
struct vc4_dpi *dpi = vc4_encoder->dpi;
+ struct drm_connector_list_iter conn_iter;
+ struct drm_connector *connector = NULL, *connector_scan;
u32 dpi_c = DPI_ENABLE | DPI_OUTPUT_ENABLE_MODE;
int ret;

- if (dpi->connector->display_info.num_bus_formats) {
- u32 bus_format = dpi->connector->display_info.bus_formats[0];
+ /* Look up the connector attached to DPI so we can get the
+ * bus_format. Ideally the bridge would tell us the
+ * bus_format we want, but it doesn't yet, so assume that it's
+ * uniform throughout the bridge chain.
+ */
+ drm_connector_list_iter_begin(dev, &conn_iter);
+ drm_for_each_connector_iter(connector_scan, &conn_iter) {
+ if (connector_scan->encoder == encoder) {
+ connector = connector_scan;
+ break;
+ }
+ }
+ drm_connector_list_iter_end(&conn_iter);
+
+ if (connector && connector->display_info.num_bus_formats) {
+ u32 bus_format = connector->display_info.bus_formats[0];

switch (bus_format) {
case MEDIA_BUS_FMT_RGB888_1X24:
@@ -199,6 +215,9 @@ static void vc4_dpi_encoder_enable(struct drm_encoder *encoder)
DRM_ERROR("Unknown media bus format %d\n", bus_format);
break;
}
+ } else {
+ /* Default to 24bit if no connector found. */
+ dpi_c |= VC4_SET_FIELD(DPI_FORMAT_24BIT_888_RGB, DPI_FORMAT);
}

if (mode->flags & DRM_MODE_FLAG_NHSYNC)
@@ -264,7 +283,7 @@ static int vc4_dpi_init_bridge(struct vc4_dpi *dpi)
return ret;
}

- if (panel)
+ if (panel)
bridge = drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_DPI);

return drm_bridge_attach(dpi->encoder, bridge, NULL);
--
2.16.2