From aec0246f3e3882065b5c29916a84b539afe4e4af Mon Sep 17 00:00:00 2001
From: Uma Shankar <uma.shankar@intel.com>
Date: Mon, 25 Sep 2017 19:26:01 +0530
Subject: [PATCH] drm/i915: Enable scanline read based on frame timestamps
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Git-commit: aec0246f3e3882065b5c29916a84b539afe4e4af
Patch-mainline: v4.15-rc1
References: FATE#322643 bsc#1055900
For certain platforms on certain encoders, timings are driven
from port instead of pipe. Thus, we can't rely on pipe scanline
registers to get the timing information. Some cases scanline
register read will not be functional.
This is causing vblank evasion logic to fail since it relies on
scanline, causing atomic update failure warnings.
This patch uses pipe framestamp and current timestamp registers
to calculate scanline. This is an indirect way to get the scanline.
It helps resolve atomic update failure for gen9 dsi platforms.
V2: Addressed Ville and Daniel's review comments. Updated the
register MACROs, handled race condition for register reads,
extracted timings from the hwmode. Removed the dependency on
crtc->config to get the encoder type.
V3: Made get scanline function generic
V4: Addressed Ville's review comments. Added a flag to decide timestamp
based scanline reporting. Changed 64bit variables to u32
V5: Adressed Ville's review comments. Put the scanline compute function
at the place of caller. Removed hwmode flags from uapi and used a local
i915 data structure instead.
V6: Used vblank hwmode to get the timings.
V7: Fixed sparse warnings, indentation and minor review comments.
V8: Limited this only for Gen9 DSI.
Credits-to: Ville Syrj채l채 <ville.syrjala@linux.intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Chandra Konduru <chandra.konduru@intel.com>
Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>
Reviewed-by: Ville Syrj채l채 <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1506347761-4201-1-git-send-email-vidya.srinivas@intel.com
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/gpu/drm/i915/i915_irq.c | 54 +++++++++++++++++++++++++++++++++++++++
drivers/gpu/drm/i915/i915_reg.h | 9 ++++++
drivers/gpu/drm/i915/intel_drv.h | 2 +
drivers/gpu/drm/i915/intel_dsi.c | 8 +++++
4 files changed, 73 insertions(+)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -783,6 +783,57 @@ static u32 g4x_get_vblank_counter(struct
return I915_READ(PIPE_FRMCOUNT_G4X(pipe));
}
+/*
+ * On certain encoders on certain platforms, pipe
+ * scanline register will not work to get the scanline,
+ * since the timings are driven from the PORT or issues
+ * with scanline register updates.
+ * This function will use Framestamp and current
+ * timestamp registers to calculate the scanline.
+ */
+static u32 __intel_get_crtc_scanline_from_timestamp(struct intel_crtc *crtc)
+{
+ struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+ struct drm_vblank_crtc *vblank =
+ &crtc->base.dev->vblank[drm_crtc_index(&crtc->base)];
+ const struct drm_display_mode *mode = &vblank->hwmode;
+ u32 vblank_start = mode->crtc_vblank_start;
+ u32 vtotal = mode->crtc_vtotal;
+ u32 htotal = mode->crtc_htotal;
+ u32 clock = mode->crtc_clock;
+ u32 scanline, scan_prev_time, scan_curr_time, scan_post_time;
+
+ /*
+ * To avoid the race condition where we might cross into the
+ * next vblank just between the PIPE_FRMTMSTMP and TIMESTAMP_CTR
+ * reads. We make sure we read PIPE_FRMTMSTMP and TIMESTAMP_CTR
+ * during the same frame.
+ */
+ do {
+ /*
+ * This field provides read back of the display
+ * pipe frame time stamp. The time stamp value
+ * is sampled at every start of vertical blank.
+ */
+ scan_prev_time = I915_READ_FW(PIPE_FRMTMSTMP(crtc->pipe));
+
+ /*
+ * The TIMESTAMP_CTR register has the current
+ * time stamp value.
+ */
+ scan_curr_time = I915_READ_FW(IVB_TIMESTAMP_CTR);
+
+ scan_post_time = I915_READ_FW(PIPE_FRMTMSTMP(crtc->pipe));
+ } while (scan_post_time != scan_prev_time);
+
+ scanline = div_u64(mul_u32_u32(scan_curr_time - scan_prev_time,
+ clock), 1000 * htotal);
+ scanline = min(scanline, vtotal - 1);
+ scanline = (scanline + vblank_start) % vtotal;
+
+ return scanline;
+}
+
/* I915_READ_FW, only for fast reads of display block, no need for forcewake etc. */
static int __intel_get_crtc_scanline(struct intel_crtc *crtc)
{
@@ -799,6 +850,9 @@ static int __intel_get_crtc_scanline(str
vblank = &crtc->base.dev->vblank[drm_crtc_index(&crtc->base)];
mode = &vblank->hwmode;
+ if (mode->private_flags & I915_MODE_FLAG_GET_SCANLINE_FROM_TIMESTAMP)
+ return __intel_get_crtc_scanline_from_timestamp(crtc);
+
vtotal = mode->crtc_vtotal;
if (mode->flags & DRM_MODE_FLAG_INTERLACE)
vtotal /= 2;
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -8809,6 +8809,15 @@ enum skl_power_gate {
#define MIPIO_TXESC_CLK_DIV2 _MMIO(0x160008)
#define GLK_TX_ESC_CLK_DIV2_MASK 0x3FF
+/* Gen4+ Timestamp and Pipe Frame time stamp registers */
+#define GEN4_TIMESTAMP _MMIO(0x2358)
+#define ILK_TIMESTAMP_HI _MMIO(0x70070)
+#define IVB_TIMESTAMP_CTR _MMIO(0x44070)
+
+#define _PIPE_FRMTMSTMP_A 0x70048
+#define PIPE_FRMTMSTMP(pipe) \
+ _MMIO_PIPE2(pipe, _PIPE_FRMTMSTMP_A)
+
/* BXT MIPI clock controls */
#define BXT_MAX_VAR_OUTPUT_KHZ 39500
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -494,6 +494,8 @@ struct intel_crtc_scaler_state {
/* drm_mode->private_flags */
#define I915_MODE_FLAG_INHERITED 1
+/* Flag to get scanline using frame time stamps */
+#define I915_MODE_FLAG_GET_SCANLINE_FROM_TIMESTAMP (1<<1)
struct intel_pipe_wm {
struct intel_wm_level wm[5];
--- a/drivers/gpu/drm/i915/intel_dsi.c
+++ b/drivers/gpu/drm/i915/intel_dsi.c
@@ -330,6 +330,10 @@ static bool intel_dsi_compute_config(str
adjusted_mode->flags = 0;
if (IS_GEN9_LP(dev_priv)) {
+ /* Enable Frame time stamp based scanline reporting */
+ adjusted_mode->private_flags |=
+ I915_MODE_FLAG_GET_SCANLINE_FROM_TIMESTAMP;
+
/* Dual link goes to DSI transcoder A. */
if (intel_dsi->ports == BIT(PORT_C))
pipe_config->cpu_transcoder = TRANSCODER_DSI_C;
@@ -1102,6 +1106,10 @@ static void bxt_dsi_get_pipe_config(stru
pixel_format_from_register_bits(fmt));
bpp = pipe_config->pipe_bpp;
+ /* Enable Frame time stamo based scanline reporting */
+ adjusted_mode->private_flags |=
+ I915_MODE_FLAG_GET_SCANLINE_FROM_TIMESTAMP;
+
/* In terms of pixels */
adjusted_mode->crtc_hdisplay =
I915_READ(BXT_MIPI_TRANS_HACTIVE(port));