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

On Fri, Mar 09, 2018 at 03:32:56PM -0800, Eric Anholt wrote:

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@anholt.net Fixes: 7b1298e05310 ("drm/vc4: Switch DPI to using the panel-bridge helper.") Cc: Boris Brezillon boris.brezillon@bootlin.com

---

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)

whitespace creep, with that fixed:

Reviewed-by: Sean Paul seanpaul@chromium.org

bridge = drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_DPI);

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

2.16.2

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