linux-kernel - [PATCH] dmaengine: ti: k3-udma-glue: fix channel enable functions

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Message-ID: <20200915164149.22123-1-grygorii.strashko@ti.com>
Date:   Tue, 15 Sep 2020 19:41:49 +0300
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Vinod Koul <vkoul@...nel.org>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        <dmaengine@...r.kernel.org>
CC:     Sekhar Nori <nsekhar@...com>, <linux-kernel@...r.kernel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        Grygorii Strashko <grygorii.strashko@...com>
Subject: [PATCH] dmaengine: ti: k3-udma-glue: fix channel enable functions

Now the K3 UDMA glue layer enable functions perform RMW operation on UDMA
RX/TX RT_CTL registers to set EN bit and enable channel, which is
incorrect, because only EN bit has to be set in those registers to enable
channel (all other bits should be cleared 0).
More over, this causes issues when bootloader leaves UDMA channel RX/TX
RT_CTL registers in incorrect state - TDOWN bit set, for example. As
result, UDMA channel will just perform teardown right after it's enabled.

Hence, fix it by writing correct values (EN=1) directly in UDMA channel
RX/TX RT_CTL registers in k3_udma_glue_enable_tx/rx_chn() functions.

Fixes: d70241913413 ("dmaengine: ti: k3-udma: Add glue layer for non DMAengine users")
Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
---
 drivers/dma/ti/k3-udma-glue.c | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/drivers/dma/ti/k3-udma-glue.c b/drivers/dma/ti/k3-udma-glue.c
index dc03880f021a..37d706cf3ba9 100644
--- a/drivers/dma/ti/k3-udma-glue.c
+++ b/drivers/dma/ti/k3-udma-glue.c
@@ -370,7 +370,6 @@ EXPORT_SYMBOL_GPL(k3_udma_glue_pop_tx_chn);
 
 int k3_udma_glue_enable_tx_chn(struct k3_udma_glue_tx_channel *tx_chn)
 {
-	u32 txrt_ctl;
 	int ret;
 
 	ret = xudma_navss_psil_pair(tx_chn->common.udmax,
@@ -383,15 +382,11 @@ int k3_udma_glue_enable_tx_chn(struct k3_udma_glue_tx_channel *tx_chn)
 
 	tx_chn->psil_paired = true;
 
-	txrt_ctl = UDMA_PEER_RT_EN_ENABLE;
 	xudma_tchanrt_write(tx_chn->udma_tchanx, UDMA_CHAN_RT_PEER_RT_EN_REG,
-			    txrt_ctl);
+			    UDMA_PEER_RT_EN_ENABLE);
 
-	txrt_ctl = xudma_tchanrt_read(tx_chn->udma_tchanx,
-				      UDMA_CHAN_RT_CTL_REG);
-	txrt_ctl |= UDMA_CHAN_RT_CTL_EN;
 	xudma_tchanrt_write(tx_chn->udma_tchanx, UDMA_CHAN_RT_CTL_REG,
-			    txrt_ctl);
+			    UDMA_CHAN_RT_CTL_EN);
 
 	k3_udma_glue_dump_tx_rt_chn(tx_chn, "txchn en");
 	return 0;
@@ -1059,7 +1054,6 @@ EXPORT_SYMBOL_GPL(k3_udma_glue_rx_flow_disable);
 
 int k3_udma_glue_enable_rx_chn(struct k3_udma_glue_rx_channel *rx_chn)
 {
-	u32 rxrt_ctl;
 	int ret;
 
 	if (rx_chn->remote)
@@ -1078,11 +1072,8 @@ int k3_udma_glue_enable_rx_chn(struct k3_udma_glue_rx_channel *rx_chn)
 
 	rx_chn->psil_paired = true;
 
-	rxrt_ctl = xudma_rchanrt_read(rx_chn->udma_rchanx,
-				      UDMA_CHAN_RT_CTL_REG);
-	rxrt_ctl |= UDMA_CHAN_RT_CTL_EN;
 	xudma_rchanrt_write(rx_chn->udma_rchanx, UDMA_CHAN_RT_CTL_REG,
-			    rxrt_ctl);
+			    UDMA_CHAN_RT_CTL_EN);
 
 	xudma_rchanrt_write(rx_chn->udma_rchanx, UDMA_CHAN_RT_PEER_RT_EN_REG,
 			    UDMA_PEER_RT_EN_ENABLE);
-- 
2.17.1