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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jon Lin <jon.lin@rock-chips.com>,
        Emil Renner Berthing <kernel@esmil.dk>,
        Heiko Stuebner <heiko@sntech.de>,
        Mark Brown <broonie@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.8 056/464] spi: rockchip: Fix error in SPI slave pio read
Date:   Mon, 17 Aug 2020 17:10:09 +0200
Message-Id: <20200817143836.444580437@linuxfoundation.org>
In-Reply-To: <20200817143833.737102804@linuxfoundation.org>
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From: Jon Lin <jon.lin@rock-chips.com>

[ Upstream commit 4294e4accf8d695ea5605f6b189008b692e3e82c ]

The RXFLR is possible larger than rx_left in Rockchip SPI, fix it.

Fixes: 01b59ce5dac8 ("spi: rockchip: use irq rather than polling")
Signed-off-by: Jon Lin <jon.lin@rock-chips.com>
Tested-by: Emil Renner Berthing <kernel@esmil.dk>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Emil Renner Berthing <kernel@esmil.dk>
Link: https://lore.kernel.org/r/20200723004356.6390-3-jon.lin@rock-chips.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/spi/spi-rockchip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index 9b8a5e1233c06..4776aa815c3fa 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -288,7 +288,7 @@ static void rockchip_spi_pio_writer(struct rockchip_spi *rs)
 static void rockchip_spi_pio_reader(struct rockchip_spi *rs)
 {
 	u32 words = readl_relaxed(rs->regs + ROCKCHIP_SPI_RXFLR);
-	u32 rx_left = rs->rx_left - words;
+	u32 rx_left = (rs->rx_left > words) ? rs->rx_left - words : 0;
 
 	/* the hardware doesn't allow us to change fifo threshold
 	 * level while spi is enabled, so instead make sure to leave
-- 
2.25.1