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path: root/drivers/gpu/drm/bridge/tc358768.c
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Diffstat (limited to 'drivers/gpu/drm/bridge/tc358768.c')
-rw-r--r--drivers/gpu/drm/bridge/tc358768.c211
1 files changed, 183 insertions, 28 deletions
diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c
index 0afb17c42ce2..9052a75aa70b 100644
--- a/drivers/gpu/drm/bridge/tc358768.c
+++ b/drivers/gpu/drm/bridge/tc358768.c
@@ -9,6 +9,7 @@
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
+#include <linux/math64.h>
#include <linux/media-bus-format.h>
#include <linux/minmax.h>
#include <linux/module.h>
@@ -158,6 +159,7 @@ struct tc358768_priv {
u32 frs; /* PLL Freqency range for HSCK (post divider) */
u32 dsiclk; /* pll_clk / 2 */
+ u32 pclk; /* incoming pclk rate */
};
static inline struct tc358768_priv *dsi_host_to_tc358768(struct mipi_dsi_host
@@ -377,6 +379,7 @@ found:
priv->prd = best_prd;
priv->frs = frs;
priv->dsiclk = best_pll / 2;
+ priv->pclk = mode->clock * 1000;
return 0;
}
@@ -635,6 +638,28 @@ static u32 tc358768_ps_to_ns(u32 ps)
return ps / 1000;
}
+static u32 tc358768_dpi_to_ns(u32 val, u32 pclk)
+{
+ return (u32)div_u64((u64)val * NANO, pclk);
+}
+
+/* Convert value in DPI pixel clock units to DSI byte count */
+static u32 tc358768_dpi_to_dsi_bytes(struct tc358768_priv *priv, u32 val)
+{
+ u64 m = (u64)val * priv->dsiclk / 4 * priv->dsi_lanes;
+ u64 n = priv->pclk;
+
+ return (u32)div_u64(m + n - 1, n);
+}
+
+static u32 tc358768_dsi_bytes_to_ns(struct tc358768_priv *priv, u32 val)
+{
+ u64 m = (u64)val * NANO;
+ u64 n = priv->dsiclk / 4 * priv->dsi_lanes;
+
+ return (u32)div_u64(m, n);
+}
+
static void tc358768_bridge_pre_enable(struct drm_bridge *bridge)
{
struct tc358768_priv *priv = bridge_to_tc358768(bridge);
@@ -644,11 +669,19 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge)
s32 raw_val;
const struct drm_display_mode *mode;
u32 hsbyteclk_ps, dsiclk_ps, ui_ps;
- u32 dsiclk, hsbyteclk, video_start;
- const u32 internal_delay = 40;
+ u32 dsiclk, hsbyteclk;
int ret, i;
struct videomode vm;
struct device *dev = priv->dev;
+ /* In pixelclock units */
+ u32 dpi_htot, dpi_data_start;
+ /* In byte units */
+ u32 dsi_dpi_htot, dsi_dpi_data_start;
+ u32 dsi_hsw, dsi_hbp, dsi_hact, dsi_hfp;
+ const u32 dsi_hss = 4; /* HSS is a short packet (4 bytes) */
+ /* In hsbyteclk units */
+ u32 dsi_vsdly;
+ const u32 internal_dly = 40;
if (mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS) {
dev_warn_once(dev, "Non-continuous mode unimplemented, falling back to continuous\n");
@@ -683,27 +716,23 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge)
case MIPI_DSI_FMT_RGB888:
val |= (0x3 << 4);
hact = vm.hactive * 3;
- video_start = (vm.hsync_len + vm.hback_porch) * 3;
data_type = MIPI_DSI_PACKED_PIXEL_STREAM_24;
break;
case MIPI_DSI_FMT_RGB666:
val |= (0x4 << 4);
hact = vm.hactive * 3;
- video_start = (vm.hsync_len + vm.hback_porch) * 3;
data_type = MIPI_DSI_PACKED_PIXEL_STREAM_18;
break;
case MIPI_DSI_FMT_RGB666_PACKED:
val |= (0x4 << 4) | BIT(3);
hact = vm.hactive * 18 / 8;
- video_start = (vm.hsync_len + vm.hback_porch) * 18 / 8;
data_type = MIPI_DSI_PIXEL_STREAM_3BYTE_18;
break;
case MIPI_DSI_FMT_RGB565:
val |= (0x5 << 4);
hact = vm.hactive * 2;
- video_start = (vm.hsync_len + vm.hback_porch) * 2;
data_type = MIPI_DSI_PACKED_PIXEL_STREAM_16;
break;
default:
@@ -713,9 +742,150 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge)
return;
}
+ /*
+ * There are three important things to make TC358768 work correctly,
+ * which are not trivial to manage:
+ *
+ * 1. Keep the DPI line-time and the DSI line-time as close to each
+ * other as possible.
+ * 2. TC358768 goes to LP mode after each line's active area. The DSI
+ * HFP period has to be long enough for entering and exiting LP mode.
+ * But it is not clear how to calculate this.
+ * 3. VSDly (video start delay) has to be long enough to ensure that the
+ * DSI TX does not start transmitting util we have started receiving
+ * pixel data from the DPI input. It is not clear how to calculate
+ * this either.
+ */
+
+ dpi_htot = vm.hactive + vm.hfront_porch + vm.hsync_len + vm.hback_porch;
+ dpi_data_start = vm.hsync_len + vm.hback_porch;
+
+ dev_dbg(dev, "dpi horiz timing (pclk): %u + %u + %u + %u = %u\n",
+ vm.hsync_len, vm.hback_porch, vm.hactive, vm.hfront_porch,
+ dpi_htot);
+
+ dev_dbg(dev, "dpi horiz timing (ns): %u + %u + %u + %u = %u\n",
+ tc358768_dpi_to_ns(vm.hsync_len, vm.pixelclock),
+ tc358768_dpi_to_ns(vm.hback_porch, vm.pixelclock),
+ tc358768_dpi_to_ns(vm.hactive, vm.pixelclock),
+ tc358768_dpi_to_ns(vm.hfront_porch, vm.pixelclock),
+ tc358768_dpi_to_ns(dpi_htot, vm.pixelclock));
+
+ dev_dbg(dev, "dpi data start (ns): %u + %u = %u\n",
+ tc358768_dpi_to_ns(vm.hsync_len, vm.pixelclock),
+ tc358768_dpi_to_ns(vm.hback_porch, vm.pixelclock),
+ tc358768_dpi_to_ns(dpi_data_start, vm.pixelclock));
+
+ dsi_dpi_htot = tc358768_dpi_to_dsi_bytes(priv, dpi_htot);
+ dsi_dpi_data_start = tc358768_dpi_to_dsi_bytes(priv, dpi_data_start);
+
+ if (dsi_dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) {
+ dsi_hsw = tc358768_dpi_to_dsi_bytes(priv, vm.hsync_len);
+ dsi_hbp = tc358768_dpi_to_dsi_bytes(priv, vm.hback_porch);
+ } else {
+ /* HBP is included in HSW in event mode */
+ dsi_hbp = 0;
+ dsi_hsw = tc358768_dpi_to_dsi_bytes(priv,
+ vm.hsync_len + vm.hback_porch);
+
+ /*
+ * The pixel packet includes the actual pixel data, and:
+ * DSI packet header = 4 bytes
+ * DCS code = 1 byte
+ * DSI packet footer = 2 bytes
+ */
+ dsi_hact = hact + 4 + 1 + 2;
+
+ dsi_hfp = dsi_dpi_htot - dsi_hact - dsi_hsw - dsi_hss;
+
+ /*
+ * Here we should check if HFP is long enough for entering LP
+ * and exiting LP, but it's not clear how to calculate that.
+ * Instead, this is a naive algorithm that just adjusts the HFP
+ * and HSW so that HFP is (at least) roughly 2/3 of the total
+ * blanking time.
+ */
+ if (dsi_hfp < (dsi_hfp + dsi_hsw + dsi_hss) * 2 / 3) {
+ u32 old_hfp = dsi_hfp;
+ u32 old_hsw = dsi_hsw;
+ u32 tot = dsi_hfp + dsi_hsw + dsi_hss;
+
+ dsi_hsw = tot / 3;
+
+ /*
+ * Seems like sometimes HSW has to be divisible by num-lanes, but
+ * not always...
+ */
+ dsi_hsw = roundup(dsi_hsw, priv->dsi_lanes);
+
+ dsi_hfp = dsi_dpi_htot - dsi_hact - dsi_hsw - dsi_hss;
+
+ dev_dbg(dev,
+ "hfp too short, adjusting dsi hfp and dsi hsw from %u, %u to %u, %u\n",
+ old_hfp, old_hsw, dsi_hfp, dsi_hsw);
+ }
+
+ dev_dbg(dev,
+ "dsi horiz timing (bytes): %u, %u + %u + %u + %u = %u\n",
+ dsi_hss, dsi_hsw, dsi_hbp, dsi_hact, dsi_hfp,
+ dsi_hss + dsi_hsw + dsi_hbp + dsi_hact + dsi_hfp);
+
+ dev_dbg(dev, "dsi horiz timing (ns): %u + %u + %u + %u + %u = %u\n",
+ tc358768_dsi_bytes_to_ns(priv, dsi_hss),
+ tc358768_dsi_bytes_to_ns(priv, dsi_hsw),
+ tc358768_dsi_bytes_to_ns(priv, dsi_hbp),
+ tc358768_dsi_bytes_to_ns(priv, dsi_hact),
+ tc358768_dsi_bytes_to_ns(priv, dsi_hfp),
+ tc358768_dsi_bytes_to_ns(priv, dsi_hss + dsi_hsw + dsi_hbp + dsi_hact + dsi_hfp));
+ }
+
+ /* VSDly calculation */
+
+ /* Start with the HW internal delay */
+ dsi_vsdly = internal_dly;
+
+ /* Convert to byte units as the other variables are in byte units */
+ dsi_vsdly *= priv->dsi_lanes;
+
+ /* Do we need more delay, in addition to the internal? */
+ if (dsi_dpi_data_start > dsi_vsdly + dsi_hss + dsi_hsw + dsi_hbp) {
+ dsi_vsdly = dsi_dpi_data_start - dsi_hss - dsi_hsw - dsi_hbp;
+ dsi_vsdly = roundup(dsi_vsdly, priv->dsi_lanes);
+ }
+
+ dev_dbg(dev, "dsi data start (bytes) %u + %u + %u + %u = %u\n",
+ dsi_vsdly, dsi_hss, dsi_hsw, dsi_hbp,
+ dsi_vsdly + dsi_hss + dsi_hsw + dsi_hbp);
+
+ dev_dbg(dev, "dsi data start (ns) %u + %u + %u + %u = %u\n",
+ tc358768_dsi_bytes_to_ns(priv, dsi_vsdly),
+ tc358768_dsi_bytes_to_ns(priv, dsi_hss),
+ tc358768_dsi_bytes_to_ns(priv, dsi_hsw),
+ tc358768_dsi_bytes_to_ns(priv, dsi_hbp),
+ tc358768_dsi_bytes_to_ns(priv, dsi_vsdly + dsi_hss + dsi_hsw + dsi_hbp));
+
+ /* Convert back to hsbyteclk */
+ dsi_vsdly /= priv->dsi_lanes;
+
+ /*
+ * The docs say that there is an internal delay of 40 cycles.
+ * However, we get underflows if we follow that rule. If we
+ * instead ignore the internal delay, things work. So either
+ * the docs are wrong or the calculations are wrong.
+ *
+ * As a temporary fix, add the internal delay here, to counter
+ * the subtraction when writing the register.
+ */
+ dsi_vsdly += internal_dly;
+
+ /* Clamp to the register max */
+ if (dsi_vsdly - internal_dly > 0x3ff) {
+ dev_warn(dev, "VSDly too high, underflows likely\n");
+ dsi_vsdly = 0x3ff + internal_dly;
+ }
+
/* VSDly[9:0] */
- video_start = max(video_start, internal_delay + 1) - internal_delay;
- tc358768_write(priv, TC358768_VSDLY, video_start);
+ tc358768_write(priv, TC358768_VSDLY, dsi_vsdly - internal_dly);
tc358768_write(priv, TC358768_DATAFMT, val);
tc358768_write(priv, TC358768_DSITX_DT, data_type);
@@ -823,18 +993,6 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge)
/* vbp */
tc358768_write(priv, TC358768_DSI_VBPR, vm.vback_porch);
-
- /* hsw * byteclk * ndl / pclk */
- val = (u32)div_u64(vm.hsync_len *
- (u64)hsbyteclk * priv->dsi_lanes,
- vm.pixelclock);
- tc358768_write(priv, TC358768_DSI_HSW, val);
-
- /* hbp * byteclk * ndl / pclk */
- val = (u32)div_u64(vm.hback_porch *
- (u64)hsbyteclk * priv->dsi_lanes,
- vm.pixelclock);
- tc358768_write(priv, TC358768_DSI_HBPR, val);
} else {
/* Set event mode */
tc358768_write(priv, TC358768_DSI_EVENT, 1);
@@ -848,16 +1006,13 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge)
/* vbp (not used in event mode) */
tc358768_write(priv, TC358768_DSI_VBPR, 0);
+ }
- /* (hsw + hbp) * byteclk * ndl / pclk */
- val = (u32)div_u64((vm.hsync_len + vm.hback_porch) *
- (u64)hsbyteclk * priv->dsi_lanes,
- vm.pixelclock);
- tc358768_write(priv, TC358768_DSI_HSW, val);
+ /* hsw (bytes) */
+ tc358768_write(priv, TC358768_DSI_HSW, dsi_hsw);
- /* hbp (not used in event mode) */
- tc358768_write(priv, TC358768_DSI_HBPR, 0);
- }
+ /* hbp (bytes) */
+ tc358768_write(priv, TC358768_DSI_HBPR, dsi_hbp);
/* hact (bytes) */
tc358768_write(priv, TC358768_DSI_HACT, hact);
generated by cgit v1.2.3 (git 2.0.4) at 2024-05-17 18:53:35 +0000