Re: [PATCH v3] OMAP2/3: I2C: Errata ID i207: Clear wrong RDR interrupt
On Thu, Apr 15, 2010 at 03:08:16PM +0300, Aaro Koskinen wrote: > Hi, > > Manjunatha GK wrote: > > Under certain rare conditions, I2C_STAT[13].RDR bit may be set > > and the corresponding interrupt fire, even there is no data in > > the receive FIFO, or the I2C data transfer is still ongoing. > > These spurious RDR events must be ignored by the software. > > > > This patch handles and ignores RDR spurious interrupts. > > > > The below sequence is required in interrupt handler for > > handling this errata: > > 1. If RDR is set to 1, clear RDR > > 2. Read I2C status register and check for BusBusy bit. If BusBusy > > bit is set, skip remaining steps. > > 3. If BusBusy bit is not set, perform read operation on I2C status > > register. > > 4. If RDR is set, clear the same. Check RDR again and clear if it sets > > RDR bit again. > > 5. Perform I2C Data Read operation N number of times(where N is value > > read from the register BUFSTAT-RXSTAT bit fields). > > > > Note : This errata is applicable for OMAP2 and OMAP3 platforms only. > > It is not applicable for OMAP4. > > > > Signed-off-by: Manjunatha GK > > Cc: linux-...@vger.kernel.org > > Cc: ben-li...@fluff.org > > Cc: Kalliguddi, Hema > > Cc: Nishanth Menon > > > > --- > > drivers/i2c/busses/i2c-omap.c | 28 > > 1 files changed, 28 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c > > index ae6f5c1..d1648da 100644 > > --- a/drivers/i2c/busses/i2c-omap.c > > +++ b/drivers/i2c/busses/i2c-omap.c > > @@ -733,6 +733,34 @@ complete: > > } > > if (stat & (OMAP_I2C_STAT_RRDY | OMAP_I2C_STAT_RDR)) { > > u8 num_bytes = 1; > > + > > + /* > > +* I2C Errata(Errata Nos. OMAP2: 1.67, OMAP3: 1.8) > > +* Not applicable for OMAP4. > > +* Under certain rare conditions, RDR could be set again > > +* when the bus is busy, then ignore the interrupt and > > +* clear the interrupt. > > +*/ > > + if ((stat & OMAP_I2C_STAT_RDR) && !cpu_is_omap44xx()) { > > + /* Step 1: If RDR is set, clear it */ > > + omap_i2c_ack_stat(dev, stat & > > OMAP_I2C_STAT_RDR); > > You know the bit is set, so just: omap_i2c_ack_stat(dev, OMAP_I2C_STAT_RDR); > > > + > > + /* Step 2: */ > > + if(!(omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG) > > + & OMAP_I2C_STAT_BB)) { > > + /* Step 3: */ > > + if(omap_i2c_read_reg(dev, > > + OMAP_I2C_STAT_REG) > > + & OMAP_I2C_STAT_RDR) { > > + omap_i2c_ack_stat(dev, stat > > + & OMAP_I2C_STAT_RDR); > > Same here. > > > + dev_err(dev->dev, > > + "I2C : RDR when the bus is > > busy.\n"); > > Remove the "I2C : " from the log, it's redundant. I'd agree, we're already prefixing this with the device name and driver name from the dev_err() call. No need to add any more. If it is in use elsewhere in the file, I'd prefer to see it removed from the other points. > > + continue; > > + } > > + > > + } > > + } > > if (dev->fifo_size) { > > if (stat & OMAP_I2C_STAT_RRDY) > > num_bytes = dev->fifo_size; > > -- > To unsubscribe from this list: send the line "unsubscribe linux-i2c" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Ben (b...@fluff.org, http://www.fluff.org/) 'a smiley only costs 4 bytes' -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v3] OMAP2/3: I2C: Errata ID i207: Clear wrong RDR interrupt
Hi, Manjunatha GK wrote: > Under certain rare conditions, I2C_STAT[13].RDR bit may be set > and the corresponding interrupt fire, even there is no data in > the receive FIFO, or the I2C data transfer is still ongoing. > These spurious RDR events must be ignored by the software. > > This patch handles and ignores RDR spurious interrupts. > > The below sequence is required in interrupt handler for > handling this errata: > 1. If RDR is set to 1, clear RDR > 2. Read I2C status register and check for BusBusy bit. If BusBusy > bit is set, skip remaining steps. > 3. If BusBusy bit is not set, perform read operation on I2C status > register. > 4. If RDR is set, clear the same. Check RDR again and clear if it sets > RDR bit again. > 5. Perform I2C Data Read operation N number of times(where N is value > read from the register BUFSTAT-RXSTAT bit fields). > > Note : This errata is applicable for OMAP2 and OMAP3 platforms only. > It is not applicable for OMAP4. > > Signed-off-by: Manjunatha GK > Cc: linux-...@vger.kernel.org > Cc: ben-li...@fluff.org > Cc: Kalliguddi, Hema > Cc: Nishanth Menon > > --- > drivers/i2c/busses/i2c-omap.c | 28 > 1 files changed, 28 insertions(+), 0 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c > index ae6f5c1..d1648da 100644 > --- a/drivers/i2c/busses/i2c-omap.c > +++ b/drivers/i2c/busses/i2c-omap.c > @@ -733,6 +733,34 @@ complete: > } > if (stat & (OMAP_I2C_STAT_RRDY | OMAP_I2C_STAT_RDR)) { > u8 num_bytes = 1; > + > + /* > + * I2C Errata(Errata Nos. OMAP2: 1.67, OMAP3: 1.8) > + * Not applicable for OMAP4. > + * Under certain rare conditions, RDR could be set again > + * when the bus is busy, then ignore the interrupt and > + * clear the interrupt. > + */ > + if ((stat & OMAP_I2C_STAT_RDR) && !cpu_is_omap44xx()) { > + /* Step 1: If RDR is set, clear it */ > + omap_i2c_ack_stat(dev, stat & > OMAP_I2C_STAT_RDR); You know the bit is set, so just: omap_i2c_ack_stat(dev, OMAP_I2C_STAT_RDR); > + > + /* Step 2: */ > + if(!(omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG) > + & OMAP_I2C_STAT_BB)) { > + /* Step 3: */ > + if(omap_i2c_read_reg(dev, > + OMAP_I2C_STAT_REG) > + & OMAP_I2C_STAT_RDR) { > + omap_i2c_ack_stat(dev, stat > + & OMAP_I2C_STAT_RDR); Same here. > + dev_err(dev->dev, > + "I2C : RDR when the bus is > busy.\n"); Remove the "I2C : " from the log, it's redundant. > + continue; > + } > + > + } > + } > if (dev->fifo_size) { > if (stat & OMAP_I2C_STAT_RRDY) > num_bytes = dev->fifo_size; -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH v3] OMAP2/3: I2C: Errata ID i207: Clear wrong RDR interrupt
Under certain rare conditions, I2C_STAT[13].RDR bit may be set and the corresponding interrupt fire, even there is no data in the receive FIFO, or the I2C data transfer is still ongoing. These spurious RDR events must be ignored by the software. This patch handles and ignores RDR spurious interrupts. The below sequence is required in interrupt handler for handling this errata: 1. If RDR is set to 1, clear RDR 2. Read I2C status register and check for BusBusy bit. If BusBusy bit is set, skip remaining steps. 3. If BusBusy bit is not set, perform read operation on I2C status register. 4. If RDR is set, clear the same. Check RDR again and clear if it sets RDR bit again. 5. Perform I2C Data Read operation N number of times(where N is value read from the register BUFSTAT-RXSTAT bit fields). Note : This errata is applicable for OMAP2 and OMAP3 platforms only. It is not applicable for OMAP4. Signed-off-by: Manjunatha GK Cc: linux-...@vger.kernel.org Cc: ben-li...@fluff.org Cc: Kalliguddi, Hema Cc: Nishanth Menon --- drivers/i2c/busses/i2c-omap.c | 28 1 files changed, 28 insertions(+), 0 deletions(-) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index ae6f5c1..d1648da 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -733,6 +733,34 @@ complete: } if (stat & (OMAP_I2C_STAT_RRDY | OMAP_I2C_STAT_RDR)) { u8 num_bytes = 1; + + /* +* I2C Errata(Errata Nos. OMAP2: 1.67, OMAP3: 1.8) +* Not applicable for OMAP4. +* Under certain rare conditions, RDR could be set again +* when the bus is busy, then ignore the interrupt and +* clear the interrupt. +*/ + if ((stat & OMAP_I2C_STAT_RDR) && !cpu_is_omap44xx()) { + /* Step 1: If RDR is set, clear it */ + omap_i2c_ack_stat(dev, stat & OMAP_I2C_STAT_RDR); + + /* Step 2: */ + if(!(omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG) + & OMAP_I2C_STAT_BB)) { + /* Step 3: */ + if(omap_i2c_read_reg(dev, + OMAP_I2C_STAT_REG) + & OMAP_I2C_STAT_RDR) { + omap_i2c_ack_stat(dev, stat + & OMAP_I2C_STAT_RDR); + dev_err(dev->dev, + "I2C : RDR when the bus is busy.\n"); + continue; + } + + } + } if (dev->fifo_size) { if (stat & OMAP_I2C_STAT_RRDY) num_bytes = dev->fifo_size; -- 1.6.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html