From:   Kevin Groeneveld <kgroeneveld@lenbrook.com>
To:     Andrzej Hajda <andrzej.hajda@intel.com>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Robert Foss <rfoss@kernel.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Cc:     Kevin Groeneveld <kgroeneveld@lenbrook.com>
Subject: [PATCH] drm/bridge: nwl-dsi: fix packet read ISR handling
Date:   Sat, 18 Mar 2023 18:36:21 -0400
Message-Id: <20230318223621.4239-1-kgroeneveld@lenbrook.com>
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In some cases the NWL_DSI_RX_PKT_PAYLOAD_DATA_RCVD interrupt flag is not
set along with NWL_DSI_RX_PKT_HDR_RCVD when the initial interrupt fires.
Since the NWL_DSI_RX_PKT_PAYLOAD_DATA_RCVD_MASK was not set then the ISR
does not fire again when NWL_DSI_RX_PKT_PAYLOAD_DATA_RCVD is finally set
and the read times out.

Also the read packet handling checks for NWL_DSI_DPHY_DIRECTION which is
not always set when the ISR for reading the payload runs. Instead it seems
better to check xfer->direction is DSI_PACKET_RECEIVE (more similar to the
send packet case).

The above two changes were required to perform a successful DCS read from
a display with a Chipone ICNL9707 driver IC.

Signed-off-by: Kevin Groeneveld <kgroeneveld@lenbrook.com>
---
 drivers/gpu/drm/bridge/nwl-dsi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
index 6dc2a4e191d7..241568a17f60 100644
--- a/drivers/gpu/drm/bridge/nwl-dsi.c
+++ b/drivers/gpu/drm/bridge/nwl-dsi.c
@@ -334,6 +334,7 @@ static int nwl_dsi_init_interrupts(struct nwl_dsi *dsi)
 {
 	u32 irq_enable = ~(u32)(NWL_DSI_TX_PKT_DONE_MASK |
 				NWL_DSI_RX_PKT_HDR_RCVD_MASK |
+				NWL_DSI_RX_PKT_PAYLOAD_DATA_RCVD_MASK |
 				NWL_DSI_TX_FIFO_OVFLW_MASK |
 				NWL_DSI_HS_TX_TIMEOUT_MASK);
 
@@ -489,7 +490,7 @@ static void nwl_dsi_finish_transmission(struct nwl_dsi *dsi, u32 status)
 	    status & NWL_DSI_TX_PKT_DONE) {
 		xfer->status = xfer->tx_len;
 		end_packet = true;
-	} else if (status & NWL_DSI_DPHY_DIRECTION &&
+	} else if (xfer->direction == DSI_PACKET_RECEIVE &&
 		   ((status & (NWL_DSI_RX_PKT_HDR_RCVD |
 			       NWL_DSI_RX_PKT_PAYLOAD_DATA_RCVD)))) {
 		end_packet = nwl_dsi_read_packet(dsi, status);
-- 
2.34.1