This is a note to let you know that I've just added the patch titled
drm/bridge: tc358768: fix THS_ZEROCNT computation
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-bridge-tc358768-fix-ths_zerocnt-computation.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 15ad2cb4e8f60bdf7414bff95f35ddcca306da61
Author: Francesco Dolcini <francesco.dolcini@xxxxxxxxxxx>
Date: Thu Apr 27 16:29:31 2023 +0200
drm/bridge: tc358768: fix THS_ZEROCNT computation
[ Upstream commit 77a089328da791118af9692543a5eedc79eb5fd4 ]
Correct computation of THS_ZEROCNT register.
This register must be set to a value that ensure that
THS_PREPARE + THS_ZERO > 145ns + 10*UI
with the actual value of (THS_PREPARE + THS_ZERO) being
((1 to 2) + 1 + (TCLK_ZEROCNT + 1) + (3 to 4)) x ByteClk cycle +
+ HSByteClk x (2 + (1 to 2)) + (PHY delay)
with PHY delay being about
(8 + (5 to 6)) x MIPIBitClk cycle in the BitClk conversion.
Fixes: ff1ca6397b1d ("drm/bridge: Add tc358768 driver")
Signed-off-by: Francesco Dolcini <francesco.dolcini@xxxxxxxxxxx>
Reviewed-by: Robert Foss <rfoss@xxxxxxxxxx>
Signed-off-by: Robert Foss <rfoss@xxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20230427142934.55435-7-francesco@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c
index de4022c864034..151eecbf6027d 100644
--- a/drivers/gpu/drm/bridge/tc358768.c
+++ b/drivers/gpu/drm/bridge/tc358768.c
@@ -744,9 +744,10 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge)
/* 40ns + 4*UI < THS_PREPARE < 85ns + 6*UI */
val = 50 + tc358768_to_ns(4 * ui_nsk);
val = tc358768_ns_to_cnt(val, dsibclk_nsk) - 1;
- /* THS_ZERO > 145ns + 10*UI */
- val2 = tc358768_ns_to_cnt(145 - tc358768_to_ns(ui_nsk), dsibclk_nsk);
- val |= (val2 - tc358768_to_ns(phy_delay_nsk)) << 8;
+ /* THS_PREPARE + THS_ZERO > 145ns + 10*UI */
+ raw_val = tc358768_ns_to_cnt(145 - tc358768_to_ns(3 * ui_nsk), dsibclk_nsk) - 10;
+ val2 = clamp(raw_val, 0, 127);
+ val |= val2 << 8;
dev_dbg(priv->dev, "THS_HEADERCNT: 0x%x\n", val);
tc358768_write(priv, TC358768_THS_HEADERCNT, val);
