[PATCH v1 7/9] drm/bridge: tc358768: fix TXTAGOCNT computation

Francesco Dolcini francesco at dolcini.it
Thu Apr 27 14:29:32 UTC 2023


From: Francesco Dolcini <francesco.dolcini at toradex.com>

Correct computation of TXTAGOCNT register.

This register must be set to a value that ensure that the
TTA-GO period = (4 x TLPX)

with the actual value of TTA-GO being

4 x (TXTAGOCNT + 1) x (HSByteClk cycle)

Fixes: ff1ca6397b1d ("drm/bridge: Add tc358768 driver")
Signed-off-by: Francesco Dolcini <francesco.dolcini at toradex.com>
---
 drivers/gpu/drm/bridge/tc358768.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c
index 36e33cba59a2..854fc04f08d0 100644
--- a/drivers/gpu/drm/bridge/tc358768.c
+++ b/drivers/gpu/drm/bridge/tc358768.c
@@ -795,7 +795,7 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge)
 
 	/* TXTAGOCNT[26:16] RXTASURECNT[10:0] */
 	val = tc358768_to_ns((lptxcnt + 1) * dsibclk_nsk * 4);
-	val = tc358768_ns_to_cnt(val, dsibclk_nsk) - 1;
+	val = tc358768_ns_to_cnt(val, dsibclk_nsk) / 4 - 1;
 	val2 = tc358768_ns_to_cnt(tc358768_to_ns((lptxcnt + 1) * dsibclk_nsk),
 				  dsibclk_nsk) - 2;
 	val = val << 16 | val2;
-- 
2.25.1



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