[PATCH AUTOSEL 6.4 03/31] drm: bridge: samsung-dsim: Drain command transfer FIFO before transfer

[Sasha Levin]

From: Marek Vasut <marex at denx.de>

[ Upstream commit 14806c6415820b1c4bc317655c40784d050a2edb ]

Wait until the command transfer FIFO is empty before loading in the next
command. The previous behavior where the code waited until command transfer
FIFO was not full suffered from transfer corruption, where the last command
in the FIFO could be overwritten in case the FIFO indicates not full, but
also does not have enough space to store another transfer yet.

Signed-off-by: Marek Vasut <marex at denx.de>
Reviewed-by: Jagan Teki <jagan at amarulasolutions.com>
Tested-by: Jagan Teki <jagan at amarulasolutions.com> # imx8mm-icore
Link: https://patchwork.freedesktop.org/patch/msgid/20230615201511.565923-1-marex@denx.de
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/gpu/drm/bridge/samsung-dsim.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index 3194cabb26b32..891ec0245a910 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -932,7 +932,7 @@ static int samsung_dsim_wait_for_hdr_fifo(struct samsung_dsim *dsi)
 	do {
 		u32 reg = samsung_dsim_read(dsi, DSIM_FIFOCTRL_REG);
 
-		if (!(reg & DSIM_SFR_HEADER_FULL))
+		if (reg & DSIM_SFR_HEADER_EMPTY)
 			return 0;
 
 		if (!cond_resched())
-- 
2.40.1