diff options
| author | Francesco Dolcini <francesco.dolcini@toradex.com> | 2023-04-14 16:13:52 +0200 |
|---|---|---|
| committer | Francesco Dolcini <francesco.dolcini@toradex.com> | 2023-04-28 14:38:45 +0200 |
| commit | 793dea46dc913f2f1c2964622904abd6e9bf96af (patch) | |
| tree | 75b262fab3eff51ce634d9e415761be43d2df830 | |
| parent | 7bc0da5a5b0819d050242595516e61103ca6c436 (diff) | |
drm/bridge: tc358768: fix TCLK_TRAILCNT computation
Correct computation of TCLK_TRAILCNT register.
The driver does not implement non-continuous clock mode, so the actual
value doesn't make a practical difference yet. However this change also
ensures that the value does not write to reserved registers bits in case
of under/overflow.
This register must be set to a value that ensures that
TCLK-TRAIL > 60ns
and
TEOT <= (105 ns + 12 x UI)
with the actual value of TCLK-TRAIL being
(TCLK_TRAILCNT + (1 to 2)) xHSByteClkCycle +
(2 + (1 to 2)) * HSBYTECLKCycle - (PHY output delay)
with PHY output delay being about
(2 to 3) x MIPIBitClk cycle in the BitClk conversion.
Upstream-Status: Submitted [https://lore.kernel.org/all/20230427142934.55435-1-francesco@dolcini.it/]
Fixes: ff1ca6397b1d ("drm/bridge: Add tc358768 driver")
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
| -rw-r--r-- | drivers/gpu/drm/bridge/tc358768.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c index 4916f2730a3b..259fa3fb5cd1 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/minmax.h> #include <linux/module.h> #include <linux/regmap.h> #include <linux/regulator/consumer.h> @@ -639,6 +640,7 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge) struct mipi_dsi_device *dsi_dev = priv->output.dev; unsigned long mode_flags = dsi_dev->mode_flags; u32 val, val2, lptxcnt, hact, data_type; + s32 raw_val; const struct drm_display_mode *mode; u32 dsibclk_nsk, dsiclk_nsk, ui_nsk, phy_delay_nsk; u32 dsiclk, dsibclk, video_start; @@ -750,9 +752,9 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge) dev_dbg(priv->dev, "TCLK_HEADERCNT: 0x%x\n", val); tc358768_write(priv, TC358768_TCLK_HEADERCNT, val); - /* TCLK_TRAIL > 60ns + 3*UI */ - val = 60 + tc358768_to_ns(3 * ui_nsk); - val = tc358768_ns_to_cnt(val, dsibclk_nsk) - 5; + /* TCLK_TRAIL > 60ns AND TEOT <= 105 ns + 12*UI */ + raw_val = tc358768_ns_to_cnt(60 + tc358768_to_ns(2 * ui_nsk), dsibclk_nsk) - 5; + val = clamp(raw_val, 0, 127); dev_dbg(priv->dev, "TCLK_TRAILCNT: 0x%x\n", val); tc358768_write(priv, TC358768_TCLK_TRAILCNT, val); |