On Sun, Jun 28, 2020 at 02:48:20PM +0300, Laurent Pinchart wrote:

Hi Sam,

On Sun, Jun 28, 2020 at 11:13:47AM +0200, Sam Ravnborg wrote:

...

On Sun, Jun 28, 2020 at 10:54:01AM +0300, Laurent Pinchart wrote:

...

The DRM bus flags reporting on which clock edge the pixel data and sync signals are sampled or driven don't make sense for LVDS panels, as the bus then uses sub-clock timings to send data. Drop those flags and add a warning in the probe function to make sure the mistake won't be repeated.

Signed-off-by: Laurent Pinchart laurent.pinchart+renesas@ideasonboard.com

drivers/gpu/drm/panel/panel-simple.c | 30 +++++++++++++++++----------- 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c index bff1cab529d2..537d75ef7fc2 100644 --- a/drivers/gpu/drm/panel/panel-simple.c +++ b/drivers/gpu/drm/panel/panel-simple.c @@ -549,6 +549,14 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc) panel_simple_parse_panel_timing_node(dev, panel, &dt); }

• if (desc->connector_type == DRM_MODE_CONNECTOR_LVDS)

• /* Catch common mistakes for LVDS panels. */
  

• WARN_ON(desc->bus_flags &
  

• 	(DRM_BUS_FLAG_PIXDATA_POSEDGE |
  

• 	 DRM_BUS_FLAG_PIXDATA_NEGEDGE |
  

• 	 DRM_BUS_FLAG_SYNC_POSEDGE |
  

• 	 DRM_BUS_FLAG_SYNC_NEGEDGE));
  

The above are only the legacy flags.

We currently have

DRM_BUS_FLAG_PIXDATA_POSEDGE = BIT(2), DRM_BUS_FLAG_PIXDATA_NEGEDGE = BIT(3), DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE = DRM_BUS_FLAG_PIXDATA_POSEDGE, DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE = DRM_BUS_FLAG_PIXDATA_NEGEDGE, DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE = DRM_BUS_FLAG_PIXDATA_NEGEDGE, DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE = DRM_BUS_FLAG_PIXDATA_POSEDGE,

Only the first two are legacy, but the last four have the same values. I could pick DRIVE or SAMPLE (the latter seems to be a better match here) instead.

We want to get rid of the legacy values, so yes, no more new users.

Sam

...

For LVDS panels I think we could check if either DRM_BUS_FLAG_DE_LOW or DRM_BUS_FLAG_DE_HIGH is set and nothing else.

A whitelist instead of a blacklist is a good idea.

...

And then as an additional check that the .bus_format is relevant.

I have a patch for that, but we first need to fix two occurrences of incorrect formats. As I couldn't find documentation for these two panels, I've replied to the patches that introduced them, and am waiting for answers.

...

Then we have managed to catch most of the mistakes for LVDS panels.

We could add checks for DPI panels too, but that would be later.

...

• drm_panel_init(&panel->base, dev, &panel_simple_funcs, desc->connector_type);

@@ -688,7 +696,7 @@ static const struct panel_desc auo_b101aw03 = { .height = 125, }, .bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH, .connector_type = DRM_MODE_CONNECTOR_LVDS,

};

@@ -1398,7 +1406,7 @@ static const struct panel_desc chunghwa_claa070wp03xg = { .height = 150, }, .bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH, .connector_type = DRM_MODE_CONNECTOR_LVDS,

};

@@ -1423,7 +1431,7 @@ static const struct panel_desc chunghwa_claa101wa01a = { .height = 120, }, .bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH, .connector_type = DRM_MODE_CONNECTOR_LVDS,

};

@@ -1448,7 +1456,7 @@ static const struct panel_desc chunghwa_claa101wb01 = { .height = 125, }, .bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH, .connector_type = DRM_MODE_CONNECTOR_LVDS,

};

@@ -2123,7 +2131,7 @@ static const struct panel_desc innolux_n156bge_l21 = { .height = 193, }, .bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH, .connector_type = DRM_MODE_CONNECTOR_LVDS,

};

@@ -2256,7 +2264,7 @@ static const struct panel_desc koe_tx26d202vm0bwa = { .disable = 1000, }, .bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH, .connector_type = DRM_MODE_CONNECTOR_LVDS,

};

@@ -2497,9 +2505,7 @@ static const struct panel_desc logictechno_lt170410_2whc = { .height = 136, }, .bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH |

•      DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE |
  

•      DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE,
  

• .bus_flags = DRM_BUS_FLAG_DE_HIGH, .connector_type = DRM_MODE_CONNECTOR_LVDS,

};

@@ -3072,7 +3078,7 @@ static const struct panel_desc samsung_ltn101nt05 = { .height = 125, }, .bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH, .connector_type = DRM_MODE_CONNECTOR_LVDS,

};

@@ -3319,7 +3325,7 @@ static const struct panel_desc starry_kr070pe2t = { .height = 86, }, .bus_format = MEDIA_BUS_FMT_RGB888_1X24,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH, .connector_type = DRM_MODE_CONNECTOR_LVDS,

};

@@ -3512,7 +3518,7 @@ static const struct panel_desc toshiba_lt089ac29000 = { .height = 116, }, .bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,

• .bus_flags = DRM_BUS_FLAG_DE_HIGH, .connector_type = DRM_MODE_CONNECTOR_LVDS,

};

-- Regards,

Laurent Pinchart