This is a note to let you know that I've just added the patch titled i2c: rcar: protect against supurious interrupts on V3U to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: i2c-rcar-protect-against-supurious-interrupts-on-v3u.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f85810cdce9d1474e8c1d810f373cd8f1679834c Author: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx> Date: Wed Dec 23 18:21:54 2020 +0100 i2c: rcar: protect against supurious interrupts on V3U [ Upstream commit 9c975c432bc0aa53a90438fc80b369cb35134a48 ] V3U creates spurious interrupts which we need to handle. This costs time until BUS_PHASE_DATA can be activated which is problematic for Gen2 SoCs and earlier. Because of this we introduce two interrupt handlers here which will call a generic main irq function once the timing critical stuff is done. Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx> Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c index 3c9c3a6f7ac8..12f6d452c0f7 100644 --- a/drivers/i2c/busses/i2c-rcar.c +++ b/drivers/i2c/busses/i2c-rcar.c @@ -625,20 +625,11 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv) * generated. It turned out that taking a spinlock at the beginning of the ISR * was already causing repeated messages. Thus, this driver was converted to * the now lockless behaviour. Please keep this in mind when hacking the driver. + * R-Car Gen3 seems to have this fixed but earlier versions than R-Car Gen2 are + * likely affected. Therefore, we have different interrupt handler entries. */ -static irqreturn_t rcar_i2c_irq(int irq, void *ptr) +static irqreturn_t rcar_i2c_irq(int irq, struct rcar_i2c_priv *priv, u32 msr) { - struct rcar_i2c_priv *priv = ptr; - u32 msr; - - /* Clear START or STOP immediately, except for REPSTART after read */ - if (likely(!(priv->flags & ID_P_REP_AFTER_RD))) - rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA); - - msr = rcar_i2c_read(priv, ICMSR); - - /* Only handle interrupts that are currently enabled */ - msr &= rcar_i2c_read(priv, ICMIER); if (!msr) { if (rcar_i2c_slave_irq(priv)) return IRQ_HANDLED; @@ -682,6 +673,41 @@ out: return IRQ_HANDLED; } +static irqreturn_t rcar_i2c_gen2_irq(int irq, void *ptr) +{ + struct rcar_i2c_priv *priv = ptr; + u32 msr; + + /* Clear START or STOP immediately, except for REPSTART after read */ + if (likely(!(priv->flags & ID_P_REP_AFTER_RD))) + rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA); + + /* Only handle interrupts that are currently enabled */ + msr = rcar_i2c_read(priv, ICMSR); + msr &= rcar_i2c_read(priv, ICMIER); + + return rcar_i2c_irq(irq, priv, msr); +} + +static irqreturn_t rcar_i2c_gen3_irq(int irq, void *ptr) +{ + struct rcar_i2c_priv *priv = ptr; + u32 msr; + + /* Only handle interrupts that are currently enabled */ + msr = rcar_i2c_read(priv, ICMSR); + msr &= rcar_i2c_read(priv, ICMIER); + + /* + * Clear START or STOP immediately, except for REPSTART after read or + * if a spurious interrupt was detected. + */ + if (likely(!(priv->flags & ID_P_REP_AFTER_RD) && msr)) + rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA); + + return rcar_i2c_irq(irq, priv, msr); +} + static struct dma_chan *rcar_i2c_request_dma_chan(struct device *dev, enum dma_transfer_direction dir, dma_addr_t port_addr) @@ -929,6 +955,7 @@ static int rcar_i2c_probe(struct platform_device *pdev) struct i2c_adapter *adap; struct device *dev = &pdev->dev; unsigned long irqflags = 0; + irqreturn_t (*irqhandler)(int irq, void *ptr) = rcar_i2c_gen3_irq; int ret; /* Otherwise logic will break because some bytes must always use PIO */ @@ -977,8 +1004,10 @@ static int rcar_i2c_probe(struct platform_device *pdev) rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */ - if (priv->devtype < I2C_RCAR_GEN3) + if (priv->devtype < I2C_RCAR_GEN3) { irqflags |= IRQF_NO_THREAD; + irqhandler = rcar_i2c_gen2_irq; + } if (priv->devtype == I2C_RCAR_GEN3) { priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL); @@ -999,7 +1028,7 @@ static int rcar_i2c_probe(struct platform_device *pdev) priv->flags |= ID_P_HOST_NOTIFY; priv->irq = platform_get_irq(pdev, 0); - ret = devm_request_irq(dev, priv->irq, rcar_i2c_irq, irqflags, dev_name(dev), priv); + ret = devm_request_irq(dev, priv->irq, irqhandler, irqflags, dev_name(dev), priv); if (ret < 0) { dev_err(dev, "cannot get irq %d\n", priv->irq); goto out_pm_disable;