From: Masahiro Yamada <yamada.masahiro@socionext.com> To: linux-i2c@vger.kernel.org Cc: Masahiro Yamada <yamada.masahiro@socionext.com>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/4] i2c: uniphier-f: fill TX-FIFO only in IRQ handler for repeated START Date: Thu, 6 Dec 2018 12:55:26 +0900 [thread overview] Message-ID: <1544068528-27657-3-git-send-email-yamada.masahiro@socionext.com> (raw) In-Reply-To: <1544068528-27657-1-git-send-email-yamada.masahiro@socionext.com> - For a repeated START condition, this controller starts data transfer immediately after the slave address is written to the TX-FIFO. - Once the TX-FIFO empty interrupt is asserted, the controller makes a pause even if additional data are written to the TX-FIFO. Given those circumstances, the data after a repeated START may not be transferred if the interrupt is asserted while the TX-FIFO is being filled up. A more reliable way is to append TX data only in the interrupt handler. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- drivers/i2c/busses/i2c-uniphier-f.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c index fad2b00..d8a5db14 100644 --- a/drivers/i2c/busses/i2c-uniphier-f.c +++ b/drivers/i2c/busses/i2c-uniphier-f.c @@ -269,7 +269,8 @@ static irqreturn_t uniphier_fi2c_interrupt(int irq, void *dev_id) return IRQ_HANDLED; } -static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr) +static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr, + bool repeat) { priv->enabled_irqs |= UNIPHIER_FI2C_INT_TE; uniphier_fi2c_set_irqs(priv); @@ -279,8 +280,12 @@ static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr) /* set slave address */ writel(UNIPHIER_FI2C_DTTX_CMD | addr << 1, priv->membase + UNIPHIER_FI2C_DTTX); - /* first chunk of data */ - uniphier_fi2c_fill_txfifo(priv, true); + /* + * First chunk of data. For a repeated START condition, do not write + * data to the TX fifo here to avoid the timing issue. + */ + if (!repeat) + uniphier_fi2c_fill_txfifo(priv, true); } static void uniphier_fi2c_rx_init(struct uniphier_fi2c_priv *priv, u16 addr) @@ -361,7 +366,7 @@ static int uniphier_fi2c_master_xfer_one(struct i2c_adapter *adap, if (is_read) uniphier_fi2c_rx_init(priv, msg->addr); else - uniphier_fi2c_tx_init(priv, msg->addr); + uniphier_fi2c_tx_init(priv, msg->addr, repeat); dev_dbg(&adap->dev, "start condition\n"); /* -- 2.7.4
WARNING: multiple messages have this Message-ID (diff)
From: Masahiro Yamada <yamada.masahiro@socionext.com> To: linux-i2c@vger.kernel.org Cc: Masahiro Yamada <yamada.masahiro@socionext.com>, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH 2/4] i2c: uniphier-f: fill TX-FIFO only in IRQ handler for repeated START Date: Thu, 6 Dec 2018 12:55:26 +0900 [thread overview] Message-ID: <1544068528-27657-3-git-send-email-yamada.masahiro@socionext.com> (raw) In-Reply-To: <1544068528-27657-1-git-send-email-yamada.masahiro@socionext.com> - For a repeated START condition, this controller starts data transfer immediately after the slave address is written to the TX-FIFO. - Once the TX-FIFO empty interrupt is asserted, the controller makes a pause even if additional data are written to the TX-FIFO. Given those circumstances, the data after a repeated START may not be transferred if the interrupt is asserted while the TX-FIFO is being filled up. A more reliable way is to append TX data only in the interrupt handler. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- drivers/i2c/busses/i2c-uniphier-f.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c index fad2b00..d8a5db14 100644 --- a/drivers/i2c/busses/i2c-uniphier-f.c +++ b/drivers/i2c/busses/i2c-uniphier-f.c @@ -269,7 +269,8 @@ static irqreturn_t uniphier_fi2c_interrupt(int irq, void *dev_id) return IRQ_HANDLED; } -static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr) +static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr, + bool repeat) { priv->enabled_irqs |= UNIPHIER_FI2C_INT_TE; uniphier_fi2c_set_irqs(priv); @@ -279,8 +280,12 @@ static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr) /* set slave address */ writel(UNIPHIER_FI2C_DTTX_CMD | addr << 1, priv->membase + UNIPHIER_FI2C_DTTX); - /* first chunk of data */ - uniphier_fi2c_fill_txfifo(priv, true); + /* + * First chunk of data. For a repeated START condition, do not write + * data to the TX fifo here to avoid the timing issue. + */ + if (!repeat) + uniphier_fi2c_fill_txfifo(priv, true); } static void uniphier_fi2c_rx_init(struct uniphier_fi2c_priv *priv, u16 addr) @@ -361,7 +366,7 @@ static int uniphier_fi2c_master_xfer_one(struct i2c_adapter *adap, if (is_read) uniphier_fi2c_rx_init(priv, msg->addr); else - uniphier_fi2c_tx_init(priv, msg->addr); + uniphier_fi2c_tx_init(priv, msg->addr, repeat); dev_dbg(&adap->dev, "start condition\n"); /* -- 2.7.4 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2018-12-06 3:56 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-12-06 3:55 [PATCH 0/4] UniPhier I2C fixes Masahiro Yamada 2018-12-06 3:55 ` Masahiro Yamada 2018-12-06 3:55 ` [PATCH 1/4] i2c: uniphier-f: fix timeout error after reading 8 bytes Masahiro Yamada 2018-12-06 3:55 ` Masahiro Yamada 2018-12-06 3:55 ` Masahiro Yamada [this message] 2018-12-06 3:55 ` [PATCH 2/4] i2c: uniphier-f: fill TX-FIFO only in IRQ handler for repeated START Masahiro Yamada 2018-12-06 3:55 ` [PATCH 3/4] i2c: uniphier: fix violation of tLOW requirement for Fast-mode Masahiro Yamada 2018-12-06 3:55 ` Masahiro Yamada 2018-12-06 3:55 ` Masahiro Yamada 2018-12-06 3:55 ` [PATCH 4/4] i2c: uniphier-f: " Masahiro Yamada 2018-12-06 3:55 ` Masahiro Yamada 2018-12-06 22:06 ` [PATCH 0/4] UniPhier I2C fixes Wolfram Sang 2018-12-06 22:06 ` Wolfram Sang
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