[Intel-gfx] [PATCH] drm/i915: Fix DSI panels with v1 MIPI sequences without a DEASSERT sequence v2

[Hans de Goede]

So far models of the Dell Venue 8 Pro, with a panel with MIPI panel
index = 3, one of which has been kindly provided to me by Jan Brummer,
where not working with the i915 driver, giving a black screen on the
first modeset.

The problem with at least these Dells is that their VBT defines a MIPI
ASSERT sequence, but not a DEASSERT sequence. Instead they DEASSERT the
reset in their INIT_OTP sequence, but the deassert must be done before
calling intel_dsi_device_ready(), so that is too late.

Simply doing the INIT_OTP sequence earlier is not enough to fix this,
because the INIT_OTP sequence also sends various MIPI packets to the
panel, which can only happen after calling intel_dsi_device_ready().

This commit fixes this by splitting the INIT_OTP sequence into everything
before the first DSI packet and everything else, including the first DSI
packet. The first part (everything before the first DSI packet) is then
used as deassert sequence.

Changed in v2:
-Split the init OTP sequence into a deassert reset and the actual init
 OTP sequence, instead of calling it earlier and then having the first
 mipi_exec_send_packet() call call intel_dsi_device_ready().

BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=82880
Related: https://bugs.freedesktop.org/show_bug.cgi?id=101205
Cc: Jan-Michael Brummer <jan.brummer at tabos.org>
Reported-by: Jan-Michael Brummer <jan.brummer at tabos.org>
Tested-by: Hans de Goede <hdegoede at redhat.com>
Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
 drivers/gpu/drm/i915/intel_dsi.c     |  1 +
 drivers/gpu/drm/i915/intel_dsi.h     |  2 +
 drivers/gpu/drm/i915/intel_dsi_vbt.c | 82 ++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
index f67d321376e4..b59ef34d25f6 100644
--- a/drivers/gpu/drm/i915/intel_dsi.c
+++ b/drivers/gpu/drm/i915/intel_dsi.c
@@ -1642,6 +1642,7 @@ static void intel_dsi_encoder_destroy(struct drm_encoder *encoder)
 	if (intel_dsi->gpio_panel)
 		gpiod_put(intel_dsi->gpio_panel);
 
+	kfree(intel_dsi->deassert_seq);
 	intel_encoder_destroy(encoder);
 }
 
diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
index 7afeb9580f41..5895588144ad 100644
--- a/drivers/gpu/drm/i915/intel_dsi.h
+++ b/drivers/gpu/drm/i915/intel_dsi.h
@@ -46,6 +46,8 @@ struct intel_dsi {
 
 	struct intel_connector *attached_connector;
 
+	u8 *deassert_seq;
+
 	/* bit mask of ports being driven */
 	u16 ports;
 
diff --git a/drivers/gpu/drm/i915/intel_dsi_vbt.c b/drivers/gpu/drm/i915/intel_dsi_vbt.c
index 91c07b0c8db9..84664f79cbef 100644
--- a/drivers/gpu/drm/i915/intel_dsi_vbt.c
+++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c
@@ -499,6 +499,86 @@ int intel_dsi_vbt_get_modes(struct intel_dsi *intel_dsi)
 	return 1;
 }
 
+/*
+ * Get len of pre-fixed deassert from init OTP, skip all delay + gpio operands
+ * and stop at the first DSI packet op.
+ */
+static int intel_vbi_get_deassert_len(const u8 *data, int total)
+{
+	int index, len;
+
+	/* index = 1 to skip sequence byte */
+	for (index = 1; index < total; index += len) {
+		switch (data[index]) {
+		case MIPI_SEQ_ELEM_SEND_PKT:
+			return index;
+		case MIPI_SEQ_ELEM_DELAY:
+			len = 5; /* 1 byte for operand + uint32 */
+			break;
+		case MIPI_SEQ_ELEM_GPIO:
+			len = 3; /* 1 byte for op, 1 for gpio_nr, 1 for value */
+			break;
+		default:
+			return 0;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Some v1 VBT MIPI sequences do the deassert in the init OTP sequence.
+ * The deassert must be done before calling intel_dsi_device_ready, so for
+ * these devices we split the init OTP sequence into a deassert sequence and
+ * the actual init OTP part.
+ */
+static void intel_dsi_fixup_dsi_sequences(struct intel_dsi *intel_dsi)
+{
+	struct drm_i915_private *dev_priv = to_i915(intel_dsi->base.base.dev);
+	int init_otp_index, len;
+	u8 *init_otp;
+
+	/* Limit this to VLV for now. */
+	if (!IS_VALLEYVIEW(dev_priv))
+		return;
+
+	/* Limit this to v1 vid-mode sequences */
+	if (intel_dsi->operation_mode != INTEL_DSI_VIDEO_MODE ||
+	    dev_priv->vbt.dsi.seq_version != 1)
+		return;
+
+	/* Only do this if there are otp and assert seqs and no deassert seq */
+	if (!dev_priv->vbt.dsi.sequence[MIPI_SEQ_INIT_OTP] ||
+	    !dev_priv->vbt.dsi.sequence[MIPI_SEQ_ASSERT_RESET] ||
+	    dev_priv->vbt.dsi.sequence[MIPI_SEQ_DEASSERT_RESET])
+		return;
+
+	/* The deassert-sequence ends at the first DSI packet */
+	init_otp_index = dev_priv->vbt.dsi.sequence[MIPI_SEQ_INIT_OTP] -
+			 (const u8 *)dev_priv->vbt.dsi.data;
+	init_otp = dev_priv->vbt.dsi.data + init_otp_index;
+	len = dev_priv->vbt.dsi.size - init_otp_index;
+	len = intel_vbi_get_deassert_len(init_otp, len);
+	if (!len)
+		return;
+
+	DRM_DEBUG_KMS("Using init OTP fragment to deassert reset\n");
+
+	/* Copy the fragment, update seq byte and terminate it */
+	intel_dsi->deassert_seq = kmemdup(init_otp, len + 1, GFP_KERNEL);
+	if (!intel_dsi->deassert_seq)
+		return;
+	intel_dsi->deassert_seq[0] = MIPI_SEQ_DEASSERT_RESET;
+	intel_dsi->deassert_seq[len] = MIPI_SEQ_ELEM_END;
+	/* Use the copy for deassert */
+	dev_priv->vbt.dsi.sequence[MIPI_SEQ_DEASSERT_RESET] =
+		intel_dsi->deassert_seq;
+	/* Replace the last byte of the fragment with init OTP seq byte */
+	init_otp[len - 1] = MIPI_SEQ_INIT_OTP;
+	/* And make MIPI_MIPI_SEQ_INIT_OTP point to it */
+	dev_priv->vbt.dsi.sequence[MIPI_SEQ_INIT_OTP] = init_otp + len - 1;
+}
+
 bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id)
 {
 	struct drm_device *dev = intel_dsi->base.base.dev;
@@ -794,5 +874,7 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id)
 		mipi_dsi_attach(intel_dsi->dsi_hosts[port]->device);
 	}
 
+	intel_dsi_fixup_dsi_sequences(intel_dsi);
+
 	return true;
 }
-- 
2.14.3