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From:   =?UTF-8?q?=C5=81ukasz=20Stelmach?= <l.stelmach@samsung.com>
To:     Kukjin Kim <kgene@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Andi Shyti <andi@etezian.org>, Mark Brown <broonie@kernel.org>,
        linux-spi@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
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Cc:     m.szyprowski@samsung.com, b.zolnierkie@samsung.com,
        =?UTF-8?q?=C5=81ukasz=20Stelmach?= <l.stelmach@samsung.com>
Subject: [PATCH v2 8/9] spi: spi-s3c64xx: Increase transfer timeout
Date:   Fri, 21 Aug 2020 18:14:00 +0200
Message-Id: <20200821161401.11307-9-l.stelmach@samsung.com>
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        <CGME20200821161407eucas1p23a283ac117d4381e087e9bacec537665@eucas1p2.samsung.com>
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Increase timeout by 30 ms for some wiggle and set the minimum value to
100 ms. This ensures a non-zero value for short transfers which
may take less than 1 ms. The timeout value does not affect
performance because it is used with a completion.

Similar formula is used in other drivers e.g. sun4i, sun6i.

Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
---
 drivers/spi/spi-s3c64xx.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 89c162efe355..ea5a22dec53d 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -473,7 +473,8 @@ static int s3c64xx_wait_for_dma(struct s3c64xx_spi_driver_data *sdd,
 
 	/* millisecs to xfer 'len' bytes @ 'cur_speed' */
 	ms = xfer->len * 8 * 1000 / sdd->cur_speed;
-	ms += 10; /* some tolerance */
+	ms += 30;               /* some tolerance */
+	ms = max(ms, 100);      /* minimum timeout */
 
 	val = msecs_to_jiffies(ms) + 10;
 	val = wait_for_completion_timeout(&sdd->xfer_completion, val);
-- 
2.26.2