linux-kernel - [PATCH] mmc: mediatek: wait dma stop bit reset to 0

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Date:   Mon, 6 Jun 2022 22:20:51 +0800
From:   Mengqi Zhang <mengqi.zhang@...iatek.com>
To:     <chaotian.jing@...iatek.com>, <ulf.hansson@...aro.org>,
        <matthias.bgg@...il.com>
CC:     <linux-mmc@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        "Mengqi Zhang" <mengqi.zhang@...iatek.com>
Subject: [PATCH] mmc: mediatek: wait dma stop bit reset to 0

MediaTek IP requires that after dma stop, it need to wait this dma stop
bit auto-reset to 0. When bus is in high loading state, it will take a
while for the dma stop complete. If there is no waiting operation here,
when program runs to clear fifo and reset, bus will hang.

In addition, there should be no return in msdc_data_xfer_next, because no
matter what error occurs here, it should continue to excute to the
following mmc_request_done. Otherwise the core layer may wait complete
forever.

Signed-off-by: Mengqi Zhang <mengqi.zhang@...iatek.com>
---
 drivers/mmc/host/mtk-sd.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
index 195dc897188b..c925f45786c2 100644
--- a/drivers/mmc/host/mtk-sd.c
+++ b/drivers/mmc/host/mtk-sd.c
@@ -1385,12 +1385,15 @@ static bool msdc_data_xfer_done(struct msdc_host *host, u32 events,
 		sdr_set_field(host->base + MSDC_DMA_CTRL, MSDC_DMA_CTRL_STOP,
 				1);
 
+		ret = readl_poll_timeout_atomic(host->base + MSDC_DMA_CTRL, val,
+						!(val & MSDC_DMA_CTRL_STOP), 1, 20000);
+		if (ret)
+			dev_dbg(host->dev, "DMA stop timed out\n");
+
 		ret = readl_poll_timeout_atomic(host->base + MSDC_DMA_CFG, val,
 						!(val & MSDC_DMA_CFG_STS), 1, 20000);
-		if (ret) {
-			dev_dbg(host->dev, "DMA stop timed out\n");
-			return false;
-		}
+		if (ret)
+			dev_dbg(host->dev, "DMA inactive timed out\n");
 
 		sdr_clr_bits(host->base + MSDC_INTEN, data_ints_mask);
 		dev_dbg(host->dev, "DMA stop\n");
@@ -2416,6 +2419,9 @@ static void msdc_cqe_disable(struct mmc_host *mmc, bool recovery)
 	if (recovery) {
 		sdr_set_field(host->base + MSDC_DMA_CTRL,
 			      MSDC_DMA_CTRL_STOP, 1);
+		if (WARN_ON(readl_poll_timeout(host->base + MSDC_DMA_CTRL, val,
+			!(val & MSDC_DMA_CTRL_STOP), 1, 3000)))
+			return;
 		if (WARN_ON(readl_poll_timeout(host->base + MSDC_DMA_CFG, val,
 			!(val & MSDC_DMA_CFG_STS), 1, 3000)))
 			return;
-- 
2.25.1