linux-kernel - [PATCH 5.18 103/112] dmaengine: dw-axi-dmac: Fix RMW on channel suspend register

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Date:   Mon, 11 Jul 2022 11:07:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Samin Guo <samin.guo@...rfivetech.com>,
        Emil Renner Berthing <kernel@...il.dk>,
        Vinod Koul <vkoul@...nel.org>
Subject: [PATCH 5.18 103/112] dmaengine: dw-axi-dmac: Fix RMW on channel suspend register

From: Emil Renner Berthing <kernel@...il.dk>

commit 49db68d45bdcad06e28a420d5d911e4178389666 upstream.

When the DMA is configured for more than 8 channels the bits controlling
suspend moves to another register. However when adding support for this
the new register would be completely overwritten in one case and
overwritten with values from the old register in another case.

Found by comparing the parallel implementation of more than 8 channel
support for the StarFive JH7100 SoC by Samin.

Fixes: 824351668a41 ("dmaengine: dw-axi-dmac: support DMAX_NUM_CHANNELS > 8")
Co-developed-by: Samin Guo <samin.guo@...rfivetech.com>
Signed-off-by: Samin Guo <samin.guo@...rfivetech.com>
Signed-off-by: Emil Renner Berthing <kernel@...il.dk>
Link: https://lore.kernel.org/r/20220627090939.1775717-1-emil.renner.berthing@canonical.com
Signed-off-by: Vinod Koul <vkoul@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -1164,8 +1164,9 @@ static int dma_chan_pause(struct dma_cha
 			BIT(chan->id) << DMAC_CHAN_SUSP_WE_SHIFT;
 		axi_dma_iowrite32(chan->chip, DMAC_CHEN, val);
 	} else {
-		val = BIT(chan->id) << DMAC_CHAN_SUSP2_SHIFT |
-		      BIT(chan->id) << DMAC_CHAN_SUSP2_WE_SHIFT;
+		val = axi_dma_ioread32(chan->chip, DMAC_CHSUSPREG);
+		val |= BIT(chan->id) << DMAC_CHAN_SUSP2_SHIFT |
+			BIT(chan->id) << DMAC_CHAN_SUSP2_WE_SHIFT;
 		axi_dma_iowrite32(chan->chip, DMAC_CHSUSPREG, val);
 	}
 
@@ -1190,12 +1191,13 @@ static inline void axi_chan_resume(struc
 {
 	u32 val;
 
-	val = axi_dma_ioread32(chan->chip, DMAC_CHEN);
 	if (chan->chip->dw->hdata->reg_map_8_channels) {
+		val = axi_dma_ioread32(chan->chip, DMAC_CHEN);
 		val &= ~(BIT(chan->id) << DMAC_CHAN_SUSP_SHIFT);
 		val |=  (BIT(chan->id) << DMAC_CHAN_SUSP_WE_SHIFT);
 		axi_dma_iowrite32(chan->chip, DMAC_CHEN, val);
 	} else {
+		val = axi_dma_ioread32(chan->chip, DMAC_CHSUSPREG);
 		val &= ~(BIT(chan->id) << DMAC_CHAN_SUSP2_SHIFT);
 		val |=  (BIT(chan->id) << DMAC_CHAN_SUSP2_WE_SHIFT);
 		axi_dma_iowrite32(chan->chip, DMAC_CHSUSPREG, val);