From: Francesco Dolcini francesco.dolcini@toradex.com
[ Upstream commit ee18698e212b1659dd0850d7e2ae0f22e16ed3d3 ]
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.
Fixes: ff1ca6397b1d ("drm/bridge: Add tc358768 driver") Signed-off-by: Francesco Dolcini francesco.dolcini@toradex.com Reviewed-by: Robert Foss rfoss@kernel.org Signed-off-by: Robert Foss rfoss@kernel.org Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-2-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-3-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-4-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-5-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-2-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-3-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-4-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-5-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-2-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-3-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-4-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-5-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-2-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-3-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-4-frances... Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-5-frances... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/bridge/tc358768.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c index 487bfe33edc88..4cb46a3e6be8c 100644 --- a/drivers/gpu/drm/bridge/tc358768.c +++ b/drivers/gpu/drm/bridge/tc358768.c @@ -10,6 +10,7 @@ #include <linux/i2c.h> #include <linux/kernel.h> #include <linux/media-bus-format.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);