[PATCH v2 0/2] Clarify display info PIXDATA bus flags

[PATCH v2 0/2] Clarify display info PIXDATA bus flags

[Laurent Pinchart]

Hello,

This patch series attemps at clarifying usage of the
DRM_BUS_FLAG_(PIXDATA|SYNC)_(POS|NEG)EDGE flags. It results from a
discussion on the mailing list available at [1].

The problem being discussed was confusion around how the
DRM_BUS_FLAG_(PIXDATA|SYNC)_POSEDGE and DRM_BUS_FLAG_(PIXDATA|SYNC)_NEGEDGE
flags could be interpreted (and are interpreted now by drivers). Patch 1/2
introduces new, more explicit flags, and explains the rationale. Patch
2/2 then updates the drivers to use the new flags.

Compared to the previous RFC series, the DRM_BUS_FLAG_SYNC_* flags have been
addressed too, and the series got rebased on top of drm-next (with one more
use of the old flags being replaced).

[1] https://www.spinics.net/lists/arm-kernel/msg677079.html

Laurent Pinchart (2):
  drm: Clarify definition of the DRM_BUS_FLAG_(PIXDATA|SYNC)_* macros
  drm: Use new DRM_BUS_FLAG_*_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags

 drivers/gpu/drm/bridge/dumb-vga-dac.c         |  6 ++--
 drivers/gpu/drm/drm_modes.c                   | 12 +++----
 drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c    |  2 +-
 drivers/gpu/drm/imx/ipuv3-crtc.c              |  2 +-
 drivers/gpu/drm/mxsfb/mxsfb_crtc.c            |  6 ++--
 .../gpu/drm/omapdrm/displays/encoder-tfp410.c |  5 +--
 .../displays/panel-lgphilips-lb035q02.c       |  5 +--
 .../omapdrm/displays/panel-nec-nl8048hl11.c   |  5 +--
 .../displays/panel-sharp-ls037v7dw01.c        |  5 +--
 .../omapdrm/displays/panel-sony-acx565akm.c   |  5 +--
 .../omapdrm/displays/panel-tpo-td028ttec1.c   |  5 +--
 .../omapdrm/displays/panel-tpo-td043mtea1.c   |  5 +--
 drivers/gpu/drm/omapdrm/dss/dsi.c             |  4 +--
 drivers/gpu/drm/omapdrm/dss/sdi.c             |  4 +--
 drivers/gpu/drm/omapdrm/omap_encoder.c        |  8 ++---
 drivers/gpu/drm/panel/panel-arm-versatile.c   |  4 +--
 drivers/gpu/drm/panel/panel-ilitek-ili9322.c  |  4 +--
 drivers/gpu/drm/panel/panel-seiko-43wvf1g.c   |  2 +-
 drivers/gpu/drm/panel/panel-simple.c          | 24 ++++++-------
 drivers/gpu/drm/pl111/pl111_display.c         |  2 +-
 drivers/gpu/drm/sun4i/sun4i_tcon.c            |  4 +--
 drivers/gpu/drm/tve200/tve200_display.c       |  3 +-
 include/drm/drm_bridge.h                      |  9 ++---
 include/drm/drm_connector.h                   | 36 ++++++++++++++++---
 24 files changed, 102 insertions(+), 65 deletions(-)

-- 
Regards,

Laurent Pinchart

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[PATCH v2 1/2] drm: Clarify definition of the DRM_BUS_FLAG_(PIXDATA|SYNC)_* macros

[Laurent Pinchart]

From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

The DRM_BUS_FLAG_PIXDATA_POSEDGE and DRM_BUS_FLAG_PIXDATA_NEGEDGE macros
and their DRM_BUS_FLAG_SYNC_* counterparts define on which pixel clock
edge data and sync signals are driven. They are however used in some
drivers to define on which pixel clock edge data and sync signals are
sampled, which should usually (but not always) be the opposite edge of
the driving edge. This creates confusion.

Create four new macros for both PIXDATA and SYNC that explicitly state
the driving and sampling edge in their name to remove the confusion. The
driving macros are defined as the opposite of the sampling macros to
made code simpler based on the assumption that the driving and sampling
edges are opposite.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
---
Changes since v1:

- Address the DRM_BUS_FLAG_SYNC_* flags
- Rebase on top of drm-next
---
 include/drm/drm_connector.h | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 665b9cae7f43..420fce85be0e 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -330,19 +330,47 @@ struct drm_display_info {
 
 #define DRM_BUS_FLAG_DE_LOW		(1<<0)
 #define DRM_BUS_FLAG_DE_HIGH		(1<<1)
-/* drive data on pos. edge */
+
+/*
+ * Don't use those two flags directly, use the DRM_BUS_FLAG_PIXDATA_DRIVE_*
+ * and DRM_BUS_FLAG_PIXDATA_SAMPLE_* variants to qualify the flags explicitly.
+ * The DRM_BUS_FLAG_PIXDATA_SAMPLE_* flags are defined as the opposite of the
+ * DRM_BUS_FLAG_PIXDATA_DRIVE_* flags to make code simpler, as signals are
+ * usually to be sampled on the opposite edge of the driving edge.
+ */
 #define DRM_BUS_FLAG_PIXDATA_POSEDGE	(1<<2)
-/* drive data on neg. edge */
 #define DRM_BUS_FLAG_PIXDATA_NEGEDGE	(1<<3)
+
+/* Drive data on rising edge */
+#define DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE	DRM_BUS_FLAG_PIXDATA_POSEDGE
+/* Drive data on falling edge */
+#define DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE	DRM_BUS_FLAG_PIXDATA_NEGEDGE
+/* Sample data on rising edge */
+#define DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE	DRM_BUS_FLAG_PIXDATA_NEGEDGE
+/* Sample data on falling edge */
+#define DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE	DRM_BUS_FLAG_PIXDATA_POSEDGE
+
 /* data is transmitted MSB to LSB on the bus */
 #define DRM_BUS_FLAG_DATA_MSB_TO_LSB	(1<<4)
 /* data is transmitted LSB to MSB on the bus */
 #define DRM_BUS_FLAG_DATA_LSB_TO_MSB	(1<<5)
-/* drive sync on pos. edge */
+
+/*
+ * Similarly to the DRM_BUS_FLAG_PIXDATA_* flags, don't use these two flags
+ * directly, use one of the DRM_BUS_FLAG_SYNC_(DRIVE|SAMPLE)_* instead.
+ */
 #define DRM_BUS_FLAG_SYNC_POSEDGE	(1<<6)
-/* drive sync on neg. edge */
 #define DRM_BUS_FLAG_SYNC_NEGEDGE	(1<<7)
 
+/* Drive sync on rising edge */
+#define DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE		DRM_BUS_FLAG_SYNC_POSEDGE
+/* Drive sync on falling edge */
+#define DRM_BUS_FLAG_SYNC_DRIVE_NEGEDGE		DRM_BUS_FLAG_SYNC_NEGEDGE
+/* Sample sync on rising edge */
+#define DRM_BUS_FLAG_SYNC_SAMPLE_POSEDGE	DRM_BUS_FLAG_SYNC_NEGEDGE
+/* Sample sync on falling edge */
+#define DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE	DRM_BUS_FLAG_SYNC_POSEDGE
+
 	/**
 	 * @bus_flags: Additional information (like pixel signal polarity) for
 	 * the pixel data on the bus, using DRM_BUS_FLAGS\_ defines.
-- 
Regards,

Laurent Pinchart

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[PATCH v2 2/2] drm: Use new DRM_BUS_FLAG_*_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags

[Laurent Pinchart]

From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

The DRM_BUS_FLAG_PIXDATA_(POS|NEG)EDGE and
DRM_BUS_FLAG_SYNC_(POS|NEG)EDGE flags are deprecated in favour of the
new DRM_BUS_FLAG_PIXDATA_(DRIVE|SAMPLE)_(POS|NEG)EDGE and
new DRM_BUS_FLAG_SYNC_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags. Replace them
through the code.

This effectively changes the value of the .sampling_edge bridge timings
field in the dumb-vga-dac driver. This is safe to do as no driver
consumes these values yet.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
---
Changes since v1:

- Clarify commit message
- Address the DRM_BUS_FLAG_SYNC_* flags
- Rebase on top of drm-next
---
 drivers/gpu/drm/bridge/dumb-vga-dac.c         |  6 ++---
 drivers/gpu/drm/drm_modes.c                   | 12 +++++-----
 drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c    |  2 +-
 drivers/gpu/drm/imx/ipuv3-crtc.c              |  2 +-
 drivers/gpu/drm/mxsfb/mxsfb_crtc.c            |  6 ++---
 .../gpu/drm/omapdrm/displays/encoder-tfp410.c |  5 ++--
 .../displays/panel-lgphilips-lb035q02.c       |  5 ++--
 .../omapdrm/displays/panel-nec-nl8048hl11.c   |  5 ++--
 .../displays/panel-sharp-ls037v7dw01.c        |  5 ++--
 .../omapdrm/displays/panel-sony-acx565akm.c   |  5 ++--
 .../omapdrm/displays/panel-tpo-td028ttec1.c   |  5 ++--
 .../omapdrm/displays/panel-tpo-td043mtea1.c   |  5 ++--
 drivers/gpu/drm/omapdrm/dss/dsi.c             |  4 ++--
 drivers/gpu/drm/omapdrm/dss/sdi.c             |  4 ++--
 drivers/gpu/drm/omapdrm/omap_encoder.c        |  8 +++----
 drivers/gpu/drm/panel/panel-arm-versatile.c   |  4 ++--
 drivers/gpu/drm/panel/panel-ilitek-ili9322.c  |  4 ++--
 drivers/gpu/drm/panel/panel-seiko-43wvf1g.c   |  2 +-
 drivers/gpu/drm/panel/panel-simple.c          | 24 +++++++++----------
 drivers/gpu/drm/pl111/pl111_display.c         |  2 +-
 drivers/gpu/drm/sun4i/sun4i_tcon.c            |  4 ++--
 drivers/gpu/drm/tve200/tve200_display.c       |  3 ++-
 include/drm/drm_bridge.h                      |  9 +++----
 23 files changed, 70 insertions(+), 61 deletions(-)

diff --git a/drivers/gpu/drm/bridge/dumb-vga-dac.c b/drivers/gpu/drm/bridge/dumb-vga-dac.c
index 9b706789a341..7dc14c22f7db 100644
--- a/drivers/gpu/drm/bridge/dumb-vga-dac.c
+++ b/drivers/gpu/drm/bridge/dumb-vga-dac.c
@@ -234,7 +234,7 @@ static int dumb_vga_remove(struct platform_device *pdev)
  */
 static const struct drm_bridge_timings default_dac_timings = {
 	/* Timing specifications, datasheet page 7 */
-	.sampling_edge = DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.sampling_edge = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
 	.setup_time_ps = 500,
 	.hold_time_ps = 1500,
 };
@@ -245,7 +245,7 @@ static const struct drm_bridge_timings default_dac_timings = {
  */
 static const struct drm_bridge_timings ti_ths8134_dac_timings = {
 	/* From timing diagram, datasheet page 9 */
-	.sampling_edge = DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.sampling_edge = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
 	/* From datasheet, page 12 */
 	.setup_time_ps = 3000,
 	/* I guess this means latched input */
@@ -258,7 +258,7 @@ static const struct drm_bridge_timings ti_ths8134_dac_timings = {
  */
 static const struct drm_bridge_timings ti_ths8135_dac_timings = {
 	/* From timing diagram, datasheet page 14 */
-	.sampling_edge = DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.sampling_edge = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
 	/* From datasheet, page 16 */
 	.setup_time_ps = 2000,
 	.hold_time_ps = 500,
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 24a750436559..bf49ee1a09e1 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -662,22 +662,22 @@ EXPORT_SYMBOL_GPL(drm_display_mode_to_videomode);
  * @bus_flags: information about pixelclk, sync and DE polarity will be stored
  * here
  *
- * Sets DRM_BUS_FLAG_DE_(LOW|HIGH),  DRM_BUS_FLAG_PIXDATA_(POS|NEG)EDGE and
- * DISPLAY_FLAGS_SYNC_(POS|NEG)EDGE in @bus_flags according to DISPLAY_FLAGS
+ * Sets DRM_BUS_FLAG_DE_(LOW|HIGH),  DRM_BUS_FLAG_PIXDATA_DRIVE_(POS|NEG)EDGE
+ * and DISPLAY_FLAGS_SYNC_(POS|NEG)EDGE in @bus_flags according to DISPLAY_FLAGS
  * found in @vm
  */
 void drm_bus_flags_from_videomode(const struct videomode *vm, u32 *bus_flags)
 {
 	*bus_flags = 0;
 	if (vm->flags & DISPLAY_FLAGS_PIXDATA_POSEDGE)
-		*bus_flags |= DRM_BUS_FLAG_PIXDATA_POSEDGE;
+		*bus_flags |= DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE;
 	if (vm->flags & DISPLAY_FLAGS_PIXDATA_NEGEDGE)
-		*bus_flags |= DRM_BUS_FLAG_PIXDATA_NEGEDGE;
+		*bus_flags |= DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE;
 
 	if (vm->flags & DISPLAY_FLAGS_SYNC_POSEDGE)
-		*bus_flags |= DRM_BUS_FLAG_SYNC_POSEDGE;
+		*bus_flags |= DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE;
 	if (vm->flags & DISPLAY_FLAGS_SYNC_NEGEDGE)
-		*bus_flags |= DRM_BUS_FLAG_SYNC_NEGEDGE;
+		*bus_flags |= DRM_BUS_FLAG_SYNC_DRIVE_NEGEDGE;
 
 	if (vm->flags & DISPLAY_FLAGS_DE_LOW)
 		*bus_flags |= DRM_BUS_FLAG_DE_LOW;
diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c
index 18afc94e4dff..1aaf8b48413e 100644
--- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c
+++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c
@@ -94,7 +94,7 @@ static void fsl_dcu_drm_crtc_mode_set_nofb(struct drm_crtc *crtc)
 	drm_display_mode_to_videomode(mode, &vm);
 
 	/* INV_PXCK as default (most display sample data on rising edge) */
-	if (!(con->display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_POSEDGE))
+	if (!(con->display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE))
 		pol |= DCU_SYN_POL_INV_PXCK;
 
 	if (vm.flags & DISPLAY_FLAGS_HSYNC_LOW)
diff --git a/drivers/gpu/drm/imx/ipuv3-crtc.c b/drivers/gpu/drm/imx/ipuv3-crtc.c
index 7d4b710b837a..82c513fc0ae3 100644
--- a/drivers/gpu/drm/imx/ipuv3-crtc.c
+++ b/drivers/gpu/drm/imx/ipuv3-crtc.c
@@ -277,7 +277,7 @@ static void ipu_crtc_mode_set_nofb(struct drm_crtc *crtc)
 	sig_cfg.enable_pol = !(imx_crtc_state->bus_flags & DRM_BUS_FLAG_DE_LOW);
 	/* Default to driving pixel data on negative clock edges */
 	sig_cfg.clk_pol = !!(imx_crtc_state->bus_flags &
-			     DRM_BUS_FLAG_PIXDATA_POSEDGE);
+			     DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE);
 	sig_cfg.bus_format = imx_crtc_state->bus_format;
 	sig_cfg.v_to_h_sync = 0;
 	sig_cfg.hsync_pin = imx_crtc_state->di_hsync_pin;
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
index 24b1f0c1432e..5c4be8366743 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
@@ -253,12 +253,12 @@ static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb)
 	if (!(bus_flags & DRM_BUS_FLAG_DE_LOW))
 		vdctrl0 |= VDCTRL0_ENABLE_ACT_HIGH;
 	/*
-	 * DRM_BUS_FLAG_PIXDATA_ defines are controller centric,
+	 * DRM_BUS_FLAG_PIXDATA_DRIVE_ defines are controller centric,
 	 * controllers VDCTRL0_DOTCLK is display centric.
 	 * Drive on positive edge       -> display samples on falling edge
-	 * DRM_BUS_FLAG_PIXDATA_POSEDGE -> VDCTRL0_DOTCLK_ACT_FALLING
+	 * DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE -> VDCTRL0_DOTCLK_ACT_FALLING
 	 */
-	if (bus_flags & DRM_BUS_FLAG_PIXDATA_POSEDGE)
+	if (bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE)
 		vdctrl0 |= VDCTRL0_DOTCLK_ACT_FALLING;
 
 	writel(vdctrl0, mxsfb->base + LCDC_VDCTRL0);
diff --git a/drivers/gpu/drm/omapdrm/displays/encoder-tfp410.c b/drivers/gpu/drm/omapdrm/displays/encoder-tfp410.c
index 82035078377a..177b44ffdcb5 100644
--- a/drivers/gpu/drm/omapdrm/displays/encoder-tfp410.c
+++ b/drivers/gpu/drm/omapdrm/displays/encoder-tfp410.c
@@ -87,8 +87,9 @@ static int tfp410_probe(struct platform_device *pdev)
 	dssdev->output_type = OMAP_DISPLAY_TYPE_DVI;
 	dssdev->owner = THIS_MODULE;
 	dssdev->of_ports = BIT(1) | BIT(0);
-	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_SYNC_POSEDGE
-			  | DRM_BUS_FLAG_PIXDATA_POSEDGE;
+	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH
+			  | DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE
+			  | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE;
 
 	dssdev->next = omapdss_of_find_connected_device(pdev->dev.of_node, 1);
 	if (IS_ERR(dssdev->next)) {
diff --git a/drivers/gpu/drm/omapdrm/displays/panel-lgphilips-lb035q02.c b/drivers/gpu/drm/omapdrm/displays/panel-lgphilips-lb035q02.c
index f37931bf1c5f..c0cbee43b3d4 100644
--- a/drivers/gpu/drm/omapdrm/displays/panel-lgphilips-lb035q02.c
+++ b/drivers/gpu/drm/omapdrm/displays/panel-lgphilips-lb035q02.c
@@ -206,8 +206,9 @@ static int lb035q02_panel_spi_probe(struct spi_device *spi)
 	 * DE is active LOW
 	 * DATA needs to be driven on the FALLING edge
 	 */
-	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_SYNC_NEGEDGE
-			  | DRM_BUS_FLAG_PIXDATA_POSEDGE;
+	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH
+			  | DRM_BUS_FLAG_SYNC_DRIVE_NEGEDGE
+			  | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE;
 
 	omapdss_display_init(dssdev);
 	omapdss_device_register(dssdev);
diff --git a/drivers/gpu/drm/omapdrm/displays/panel-nec-nl8048hl11.c b/drivers/gpu/drm/omapdrm/displays/panel-nec-nl8048hl11.c
index 8f2fb3d0492f..ccb5fec09681 100644
--- a/drivers/gpu/drm/omapdrm/displays/panel-nec-nl8048hl11.c
+++ b/drivers/gpu/drm/omapdrm/displays/panel-nec-nl8048hl11.c
@@ -195,8 +195,9 @@ static int nec_8048_probe(struct spi_device *spi)
 	dssdev->owner = THIS_MODULE;
 	dssdev->of_ports = BIT(0);
 	dssdev->ops_flags = OMAP_DSS_DEVICE_OP_MODES;
-	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_SYNC_POSEDGE
-			  | DRM_BUS_FLAG_PIXDATA_POSEDGE;
+	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH
+			  | DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE
+			  | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE;
 
 	omapdss_display_init(dssdev);
 	omapdss_device_register(dssdev);
diff --git a/drivers/gpu/drm/omapdrm/displays/panel-sharp-ls037v7dw01.c b/drivers/gpu/drm/omapdrm/displays/panel-sharp-ls037v7dw01.c
index 8d5d7f775b55..d4642004d455 100644
--- a/drivers/gpu/drm/omapdrm/displays/panel-sharp-ls037v7dw01.c
+++ b/drivers/gpu/drm/omapdrm/displays/panel-sharp-ls037v7dw01.c
@@ -215,8 +215,9 @@ static int sharp_ls_probe(struct platform_device *pdev)
 	 * Note: According to the panel documentation:
 	 * DATA needs to be driven on the FALLING edge
 	 */
-	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_SYNC_NEGEDGE
-			  | DRM_BUS_FLAG_PIXDATA_POSEDGE;
+	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH
+			  | DRM_BUS_FLAG_SYNC_DRIVE_NEGEDGE
+			  | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE;
 
 	omapdss_display_init(dssdev);
 	omapdss_device_register(dssdev);
diff --git a/drivers/gpu/drm/omapdrm/displays/panel-sony-acx565akm.c b/drivers/gpu/drm/omapdrm/displays/panel-sony-acx565akm.c
index b8360cef3754..97b5447decd2 100644
--- a/drivers/gpu/drm/omapdrm/displays/panel-sony-acx565akm.c
+++ b/drivers/gpu/drm/omapdrm/displays/panel-sony-acx565akm.c
@@ -709,8 +709,9 @@ static int acx565akm_probe(struct spi_device *spi)
 	dssdev->owner = THIS_MODULE;
 	dssdev->of_ports = BIT(0);
 	dssdev->ops_flags = OMAP_DSS_DEVICE_OP_MODES;
-	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_SYNC_NEGEDGE
-			  | DRM_BUS_FLAG_PIXDATA_POSEDGE;
+	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH
+			  | DRM_BUS_FLAG_SYNC_DRIVE_NEGEDGE
+			  | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE;
 
 	omapdss_display_init(dssdev);
 	omapdss_device_register(dssdev);
diff --git a/drivers/gpu/drm/omapdrm/displays/panel-tpo-td028ttec1.c b/drivers/gpu/drm/omapdrm/displays/panel-tpo-td028ttec1.c
index 721c5bb3bdef..cddc509917d1 100644
--- a/drivers/gpu/drm/omapdrm/displays/panel-tpo-td028ttec1.c
+++ b/drivers/gpu/drm/omapdrm/displays/panel-tpo-td028ttec1.c
@@ -329,8 +329,9 @@ static int td028ttec1_panel_probe(struct spi_device *spi)
 	 * Note: According to the panel documentation:
 	 * SYNC needs to be driven on the FALLING edge
 	 */
-	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_SYNC_POSEDGE
-			  | DRM_BUS_FLAG_PIXDATA_NEGEDGE;
+	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH
+			  | DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE
+			  | DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE;
 
 	omapdss_display_init(dssdev);
 	omapdss_device_register(dssdev);
diff --git a/drivers/gpu/drm/omapdrm/displays/panel-tpo-td043mtea1.c b/drivers/gpu/drm/omapdrm/displays/panel-tpo-td043mtea1.c
index 50960018dbe8..46314b9ada26 100644
--- a/drivers/gpu/drm/omapdrm/displays/panel-tpo-td043mtea1.c
+++ b/drivers/gpu/drm/omapdrm/displays/panel-tpo-td043mtea1.c
@@ -428,8 +428,9 @@ static int tpo_td043_probe(struct spi_device *spi)
 	 * Note: According to the panel documentation:
 	 * SYNC needs to be driven on the FALLING edge
 	 */
-	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_SYNC_POSEDGE
-			  | DRM_BUS_FLAG_PIXDATA_NEGEDGE;
+	dssdev->bus_flags = DRM_BUS_FLAG_DE_HIGH
+			  | DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE
+			  | DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE;
 
 	omapdss_display_init(dssdev);
 	omapdss_device_register(dssdev);
diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
index 0ba4670fd6cf..e8df291cd3b2 100644
--- a/drivers/gpu/drm/omapdrm/dss/dsi.c
+++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
@@ -5118,9 +5118,9 @@ static int dsi_init_output(struct dsi_data *dsi)
 	out->ops = &dsi_ops;
 	out->owner = THIS_MODULE;
 	out->of_ports = BIT(0);
-	out->bus_flags = DRM_BUS_FLAG_PIXDATA_POSEDGE
+	out->bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE
 		       | DRM_BUS_FLAG_DE_HIGH
-		       | DRM_BUS_FLAG_SYNC_NEGEDGE;
+		       | DRM_BUS_FLAG_SYNC_DRIVE_NEGEDGE;
 
 	r = omapdss_device_init_output(out);
 	if (r < 0)
diff --git a/drivers/gpu/drm/omapdrm/dss/sdi.c b/drivers/gpu/drm/omapdrm/dss/sdi.c
index 38b0bf19538d..453d6fcb2069 100644
--- a/drivers/gpu/drm/omapdrm/dss/sdi.c
+++ b/drivers/gpu/drm/omapdrm/dss/sdi.c
@@ -279,8 +279,8 @@ static int sdi_init_output(struct sdi_device *sdi)
 	out->of_ports = BIT(1);
 	out->ops = &sdi_ops;
 	out->owner = THIS_MODULE;
-	out->bus_flags = DRM_BUS_FLAG_PIXDATA_POSEDGE	/* 15.5.9.1.2 */
-		       | DRM_BUS_FLAG_SYNC_POSEDGE;
+	out->bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE	/* 15.5.9.1.2 */
+		       | DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE;
 
 	r = omapdss_device_init_output(out);
 	if (r < 0)
diff --git a/drivers/gpu/drm/omapdrm/omap_encoder.c b/drivers/gpu/drm/omapdrm/omap_encoder.c
index 4fb8b3fbd688..12904b5a79aa 100644
--- a/drivers/gpu/drm/omapdrm/omap_encoder.c
+++ b/drivers/gpu/drm/omapdrm/omap_encoder.c
@@ -87,17 +87,17 @@ static void omap_encoder_mode_set(struct drm_encoder *encoder,
 
 		if (!(vm.flags & (DISPLAY_FLAGS_PIXDATA_POSEDGE |
 				  DISPLAY_FLAGS_PIXDATA_NEGEDGE))) {
-			if (bus_flags & DRM_BUS_FLAG_PIXDATA_POSEDGE)
+			if (bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE)
 				vm.flags |= DISPLAY_FLAGS_PIXDATA_POSEDGE;
-			else if (bus_flags & DRM_BUS_FLAG_PIXDATA_NEGEDGE)
+			else if (bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE)
 				vm.flags |= DISPLAY_FLAGS_PIXDATA_NEGEDGE;
 		}
 
 		if (!(vm.flags & (DISPLAY_FLAGS_SYNC_POSEDGE |
 				  DISPLAY_FLAGS_SYNC_NEGEDGE))) {
-			if (bus_flags & DRM_BUS_FLAG_SYNC_POSEDGE)
+			if (bus_flags & DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE)
 				vm.flags |= DISPLAY_FLAGS_SYNC_POSEDGE;
-			else if (bus_flags & DRM_BUS_FLAG_SYNC_NEGEDGE)
+			else if (bus_flags & DRM_BUS_FLAG_SYNC_DRIVE_NEGEDGE)
 				vm.flags |= DISPLAY_FLAGS_SYNC_NEGEDGE;
 		}
 	}
diff --git a/drivers/gpu/drm/panel/panel-arm-versatile.c b/drivers/gpu/drm/panel/panel-arm-versatile.c
index b428c4678106..078fa2c0eef8 100644
--- a/drivers/gpu/drm/panel/panel-arm-versatile.c
+++ b/drivers/gpu/drm/panel/panel-arm-versatile.c
@@ -191,7 +191,7 @@ static const struct versatile_panel_type versatile_panels[] = {
 			.vrefresh = 390,
 			.flags = DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC,
 		},
-		.bus_flags = DRM_BUS_FLAG_PIXDATA_NEGEDGE,
+		.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
 	},
 	/*
 	 * Sanyo ALR252RGT 240x320 portrait display found on the
@@ -215,7 +215,7 @@ static const struct versatile_panel_type versatile_panels[] = {
 			.vrefresh = 116,
 			.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
 		},
-		.bus_flags = DRM_BUS_FLAG_PIXDATA_NEGEDGE,
+		.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
 		.ib2 = true,
 	},
 };
diff --git a/drivers/gpu/drm/panel/panel-ilitek-ili9322.c b/drivers/gpu/drm/panel/panel-ilitek-ili9322.c
index bd38bf4f1ba6..35497ff08391 100644
--- a/drivers/gpu/drm/panel/panel-ilitek-ili9322.c
+++ b/drivers/gpu/drm/panel/panel-ilitek-ili9322.c
@@ -412,11 +412,11 @@ static int ili9322_init(struct drm_panel *panel, struct ili9322 *ili)
 	if (ili->conf->dclk_active_high) {
 		reg = ILI9322_POL_DCLK;
 		connector->display_info.bus_flags |=
-			DRM_BUS_FLAG_PIXDATA_POSEDGE;
+			DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE;
 	} else {
 		reg = 0;
 		connector->display_info.bus_flags |=
-			DRM_BUS_FLAG_PIXDATA_NEGEDGE;
+			DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE;
 	}
 	if (ili->conf->de_active_high) {
 		reg |= ILI9322_POL_DE;
diff --git a/drivers/gpu/drm/panel/panel-seiko-43wvf1g.c b/drivers/gpu/drm/panel/panel-seiko-43wvf1g.c
index 2d99e28ff117..bdcc5d80823d 100644
--- a/drivers/gpu/drm/panel/panel-seiko-43wvf1g.c
+++ b/drivers/gpu/drm/panel/panel-seiko-43wvf1g.c
@@ -328,7 +328,7 @@ static const struct seiko_panel_desc seiko_43wvf1g = {
 		.height = 57,
 	},
 	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
-	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_NEGEDGE,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
 };
 
 static const struct of_device_id platform_of_match[] = {
diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 5fbee837b0db..af6c84a726ef 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -890,7 +890,7 @@ static const struct panel_desc cdtech_s043wq26h_ct7 = {
 		.width = 95,
 		.height = 54,
 	},
-	.bus_flags = DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
 };
 
 static const struct drm_display_mode cdtech_s070wv95_ct16_mode = {
@@ -1010,7 +1010,7 @@ static const struct panel_desc dataimage_scf0700c48ggu18 = {
 		.height = 91,
 	},
 	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
-	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
 };
 
 static const struct display_timing dlc_dlc0700yzg_1_timing = {
@@ -1095,7 +1095,7 @@ static const struct panel_desc edt_et057090dhu = {
 		.height = 86,
 	},
 	.bus_format = MEDIA_BUS_FMT_RGB666_1X18,
-	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_NEGEDGE,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
 };
 
 static const struct drm_display_mode edt_etm0700g0dh6_mode = {
@@ -1121,7 +1121,7 @@ static const struct panel_desc edt_etm0700g0dh6 = {
 		.height = 91,
 	},
 	.bus_format = MEDIA_BUS_FMT_RGB666_1X18,
-	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_NEGEDGE,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
 };
 
 static const struct panel_desc edt_etm0700g0bdh6 = {
@@ -1133,7 +1133,7 @@ static const struct panel_desc edt_etm0700g0bdh6 = {
 		.height = 91,
 	},
 	.bus_format = MEDIA_BUS_FMT_RGB666_1X18,
-	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
 };
 
 static const struct drm_display_mode foxlink_fl500wvr00_a0t_mode = {
@@ -1287,7 +1287,7 @@ static const struct panel_desc innolux_at043tn24 = {
 		.height = 54,
 	},
 	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
-	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
 };
 
 static const struct drm_display_mode innolux_at070tn92_mode = {
@@ -1770,7 +1770,7 @@ static const struct panel_desc nec_nl4827hc19_05b = {
 		.height = 54,
 	},
 	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
-	.bus_flags = DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
 };
 
 static const struct drm_display_mode netron_dy_e231732_mode = {
@@ -1819,8 +1819,8 @@ static const struct panel_desc newhaven_nhd_43_480272ef_atxl = {
 		.height = 54,
 	},
 	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
-	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_POSEDGE |
-		     DRM_BUS_FLAG_SYNC_POSEDGE,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE |
+		     DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE,
 };
 
 static const struct display_timing nlt_nl192108ac18_02d_timing = {
@@ -1981,7 +1981,7 @@ static const struct panel_desc ortustech_com43h4m85ulc = {
 		.height = 93,
 	},
 	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
-	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
 };
 
 static const struct drm_display_mode qd43003c0_40_mode = {
@@ -2326,7 +2326,7 @@ static const struct panel_desc toshiba_lt089ac29000 = {
 		.height = 116,
 	},
 	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
-	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
 };
 
 static const struct drm_display_mode tpk_f07a_0102_mode = {
@@ -2349,7 +2349,7 @@ static const struct panel_desc tpk_f07a_0102 = {
 		.width = 152,
 		.height = 91,
 	},
-	.bus_flags = DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
 };
 
 static const struct drm_display_mode tpk_f10a_0102_mode = {
diff --git a/drivers/gpu/drm/pl111/pl111_display.c b/drivers/gpu/drm/pl111/pl111_display.c
index 754f6b25f265..0c5d391f0a8f 100644
--- a/drivers/gpu/drm/pl111/pl111_display.c
+++ b/drivers/gpu/drm/pl111/pl111_display.c
@@ -188,7 +188,7 @@ static void pl111_display_enable(struct drm_simple_display_pipe *pipe,
 			tim2 |= TIM2_IOE;
 
 		if (connector->display_info.bus_flags &
-		    DRM_BUS_FLAG_PIXDATA_NEGEDGE)
+		    DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE)
 			tim2 |= TIM2_IPC;
 	}
 
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index 0420f5c978b9..a19dc28bcb36 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -561,10 +561,10 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
 	 * Following code is a way to avoid quirks all around TCON
 	 * and DOTCLOCK drivers.
 	 */
-	if (display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_POSEDGE)
+	if (display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE)
 		clk_set_phase(tcon->dclk, 240);
 
-	if (display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_NEGEDGE)
+	if (display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE)
 		clk_set_phase(tcon->dclk, 0);
 
 	regmap_update_bits(tcon->regs, SUN4I_TCON0_IO_POL_REG,
diff --git a/drivers/gpu/drm/tve200/tve200_display.c b/drivers/gpu/drm/tve200/tve200_display.c
index e8723a2412a6..d775d10dbe6a 100644
--- a/drivers/gpu/drm/tve200/tve200_display.c
+++ b/drivers/gpu/drm/tve200/tve200_display.c
@@ -149,7 +149,8 @@ static void tve200_display_enable(struct drm_simple_display_pipe *pipe,
 	/* Vsync IRQ at start of Vsync at first */
 	ctrl1 |= TVE200_VSTSTYPE_VSYNC;
 
-	if (connector->display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_NEGEDGE)
+	if (connector->display_info.bus_flags &
+	    DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE)
 		ctrl1 |= TVE200_CTRL_TVCLKP;
 
 	if ((mode->hdisplay == 352 && mode->vdisplay == 240) || /* SIF(525) */
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index bd850747ce54..bf81fb573a5e 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -246,10 +246,11 @@ struct drm_bridge_timings {
 	/**
 	 * @sampling_edge:
 	 *
-	 * Tells whether the bridge samples the digital input signal
-	 * from the display engine on the positive or negative edge of the
-	 * clock, this should reuse the DRM_BUS_FLAG_PIXDATA_[POS|NEG]EDGE
-	 * bitwise flags from the DRM connector (bit 2 and 3 valid).
+	 * Tells whether the bridge samples the digital input signals from the
+	 * display engine on the positive or negative edge of the clock. This
+	 * should use the DRM_BUS_FLAG_PIXDATA_SAMPLE_[POS|NEG]EDGE and
+	 * DRM_BUS_FLAG_SYNC_SAMPLE_[POS|NEG]EDGE bitwise flags from the DRM
+	 * connector (bit 2, 3, 6 and 7 valid).
 	 */
 	u32 sampling_edge;
 	/**
-- 
Regards,

Laurent Pinchart

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Re: [PATCH v2 2/2] drm: Use new DRM_BUS_FLAG_*_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags

[Tomi Valkeinen]

Hi,

On 05/12/18 10:49, Laurent Pinchart wrote:
> From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> 
> The DRM_BUS_FLAG_PIXDATA_(POS|NEG)EDGE and
> DRM_BUS_FLAG_SYNC_(POS|NEG)EDGE flags are deprecated in favour of the
> new DRM_BUS_FLAG_PIXDATA_(DRIVE|SAMPLE)_(POS|NEG)EDGE and
> new DRM_BUS_FLAG_SYNC_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags. Replace them
> through the code.
> 
> This effectively changes the value of the .sampling_edge bridge timings
> field in the dumb-vga-dac driver. This is safe to do as no driver
> consumes these values yet.

When to use which?

Looking at the omap drivers, you use the DRIVE variant. But if the
encoder/panel is describing what it wants as input, shouldn't it use the
SAMPLE variant?

 Tomi

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Re: [PATCH v2 2/2] drm: Use new DRM_BUS_FLAG_*_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags

[Stefan Agner]

On 05.12.2018 11:42, Tomi Valkeinen wrote:
> Hi,
> 
> On 05/12/18 10:49, Laurent Pinchart wrote:
>> From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
>>
>> The DRM_BUS_FLAG_PIXDATA_(POS|NEG)EDGE and
>> DRM_BUS_FLAG_SYNC_(POS|NEG)EDGE flags are deprecated in favour of the
>> new DRM_BUS_FLAG_PIXDATA_(DRIVE|SAMPLE)_(POS|NEG)EDGE and
>> new DRM_BUS_FLAG_SYNC_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags. Replace them
>> through the code.
>>
>> This effectively changes the value of the .sampling_edge bridge timings
>> field in the dumb-vga-dac driver. This is safe to do as no driver
>> consumes these values yet.
> 
> When to use which?

I guess whatever works best, e.g. if a display controller uses the
sample perspective, to describe its register, I would use the matching
defines.

> 
> Looking at the omap drivers, you use the DRIVE variant. But if the
> encoder/panel is describing what it wants as input, shouldn't it use the
> SAMPLE variant?

If it is fine to use either one in display controllers or displays, I
guess that is fine. I'd rather prefer a mechanical change right now, and
do logical fixes on a per case basis. However, in this patch the
dumb-vga-dac.c case already breaks that rule. Maybe it should be  a
separate patch?

--
Stefan


> 
>  Tomi
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Re: [PATCH v2 2/2] drm: Use new DRM_BUS_FLAG_*_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags

[Laurent Pinchart]

Hi Tomi,

On Wednesday, 5 December 2018 12:42:12 EET Tomi Valkeinen wrote:
> On 05/12/18 10:49, Laurent Pinchart wrote:
> > From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> > 
> > The DRM_BUS_FLAG_PIXDATA_(POS|NEG)EDGE and
> > DRM_BUS_FLAG_SYNC_(POS|NEG)EDGE flags are deprecated in favour of the
> > new DRM_BUS_FLAG_PIXDATA_(DRIVE|SAMPLE)_(POS|NEG)EDGE and
> > new DRM_BUS_FLAG_SYNC_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags. Replace them
> > through the code.
> > 
> > This effectively changes the value of the .sampling_edge bridge timings
> > field in the dumb-vga-dac driver. This is safe to do as no driver
> > consumes these values yet.
> 
> When to use which?

The idea is to use the flags that correspond to the side corresponding to the 
code. A bridge driver, in its input_bus_flags, would use the sample flags. A 
display controller driver would likely use the drive flags. If we later extend 
drm_bridge to handle polarities on the source side of the bridge, the drive 
flags should be used there.

It also makes sense to follow the perspective described in datasheets and 
hardware registers. If an internal encoder is documented using the driving 
perspective for its input signals, usage of the drive flags is likely best.

In a nutshell, use the flags that result in the simplest possible code.

> Looking at the omap drivers, you use the DRIVE variant. But if the
> encoder/panel is describing what it wants as input, shouldn't it use the
> SAMPLE variant?

I have to confess I haven't paid much attention to the omapdrm/displays/ 
drivers as we're in the process of removing them, but I think you're right 
there. For the SDI encoder, the datasheet documents polarities from a drive 
perspective, so I've kept that. For the DSI encoder there's no documented 
polarities, so I used the drive perspective there as well to remain 
consistent.

-- 
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Laurent Pinchart



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Re: [PATCH v2 2/2] drm: Use new DRM_BUS_FLAG_*_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags

[Laurent Pinchart]

Hi Stefan,

(Maxime, there's a question for you below)

On Wednesday, 5 December 2018 14:21:56 EET Stefan Agner wrote:
> On 05.12.2018 11:42, Tomi Valkeinen wrote:
> > On 05/12/18 10:49, Laurent Pinchart wrote:
> >> From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> >> 
> >> The DRM_BUS_FLAG_PIXDATA_(POS|NEG)EDGE and
> >> DRM_BUS_FLAG_SYNC_(POS|NEG)EDGE flags are deprecated in favour of the
> >> new DRM_BUS_FLAG_PIXDATA_(DRIVE|SAMPLE)_(POS|NEG)EDGE and
> >> new DRM_BUS_FLAG_SYNC_(DRIVE|SAMPLE)_(POS|NEG)EDGE flags. Replace them
> >> through the code.
> >> 
> >> This effectively changes the value of the .sampling_edge bridge timings
> >> field in the dumb-vga-dac driver. This is safe to do as no driver
> >> consumes these values yet.
> > 
> > When to use which?
> 
> I guess whatever works best, e.g. if a display controller uses the
> sample perspective, to describe its register, I would use the matching
> defines.
> 
> > Looking at the omap drivers, you use the DRIVE variant. But if the
> > encoder/panel is describing what it wants as input, shouldn't it use the
> > SAMPLE variant?
> 
> If it is fine to use either one in display controllers or displays, I
> guess that is fine. I'd rather prefer a mechanical change right now, and
> do logical fixes on a per case basis. However, in this patch the
> dumb-vga-dac.c case already breaks that rule. Maybe it should be a
> separate patch?

If that's preferred I'll submit a v3 with this patch split in two. Maxime ?

-- 
Regards,

Laurent Pinchart



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