linux-kernel - [PATCH v2] spi: spi-mtk-nor: Optimize timeout for dma read

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Date:   Mon, 14 Nov 2022 16:13:27 +0800
From:   Bayi Cheng <bayi.cheng@...iatek.com>
To:     Mark Brown <broonie@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Ikjoon Jang <ikjn@...omium.org>
CC:     <linux-spi@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>,
        bayi cheng <bayi.cheng@...iatek.com>
Subject: [PATCH v2] spi: spi-mtk-nor: Optimize timeout for dma read

From: bayi cheng <bayi.cheng@...iatek.com>

The timeout value of the current dma read is unreasonable. For example,
If the spi flash clock is 26Mhz, It will takes about 1.3ms to read a
4KB data in spi mode. But the actual measurement exceeds 50s when a
dma read timeout is encountered.

In order to be more accurately, It is necessary to use usecs_to_jiffies,
After modification, the measured timeout value is about 130ms.

Signed-off-by: bayi cheng <bayi.cheng@...iatek.com>
---
Change in v2:
  -Change the type of "timeout" from ulong to u32.
  -Replace max_t with max.
  -Replace msecs_to_jiffies with usecs_to_jiffies.
---
---
 drivers/spi/spi-mtk-nor.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-mtk-nor.c b/drivers/spi/spi-mtk-nor.c
index d167699a1a96..58eca18b28b0 100644
--- a/drivers/spi/spi-mtk-nor.c
+++ b/drivers/spi/spi-mtk-nor.c
@@ -354,7 +354,7 @@ static int mtk_nor_dma_exec(struct mtk_nor *sp, u32 from, unsigned int length,
 			    dma_addr_t dma_addr)
 {
 	int ret = 0;
-	ulong delay;
+	u32 delay, timeout;
 	u32 reg;
 
 	writel(from, sp->base + MTK_NOR_REG_DMA_FADR);
@@ -376,15 +376,16 @@ static int mtk_nor_dma_exec(struct mtk_nor *sp, u32 from, unsigned int length,
 	mtk_nor_rmw(sp, MTK_NOR_REG_DMA_CTL, MTK_NOR_DMA_START, 0);
 
 	delay = CLK_TO_US(sp, (length + 5) * BITS_PER_BYTE);
+	timeout = (delay + 1) * 100;
 
 	if (sp->has_irq) {
 		if (!wait_for_completion_timeout(&sp->op_done,
-						 (delay + 1) * 100))
+		    usecs_to_jiffies(max(timeout, 10000U))))
 			ret = -ETIMEDOUT;
 	} else {
 		ret = readl_poll_timeout(sp->base + MTK_NOR_REG_DMA_CTL, reg,
 					 !(reg & MTK_NOR_DMA_START), delay / 3,
-					 (delay + 1) * 100);
+					 timeout);
 	}
 
 	if (ret < 0)
-- 
2.25.1