* [PATCH 0/2] omap i2c interrupt handler fixes @ 2009-12-16 13:43 Alexander Shishkin 2009-12-16 13:43 ` [PATCH 1/2] omap i2c: make errata 1.153 workaround a separate function Alexander Shishkin 0 siblings, 1 reply; 5+ messages in thread From: Alexander Shishkin @ 2009-12-16 13:43 UTC (permalink / raw) To: ben-linux-elnMNo+KYs3YtjvyW6yDsg Cc: linux-omap-u79uwXL29TY76Z2rM5mHXA, linux-i2c-u79uwXL29TY76Z2rM5mHXA Hi, This is the second version of the patch that I've sent to linux-omap to address this issue. This time I've moved the whole errata workaround bit to a separate function to get rid of too long lines and a couple of extra levels of indentation. The actual fix is the same as the first time, it adds a timeout to a busy loop which happens to take place in an interrupt handler and is capable of hanging the kernel. Regards, -- Alex ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH 1/2] omap i2c: make errata 1.153 workaround a separate function 2009-12-16 13:43 [PATCH 0/2] omap i2c interrupt handler fixes Alexander Shishkin @ 2009-12-16 13:43 ` Alexander Shishkin 2009-12-16 13:43 ` Alexander Shishkin 0 siblings, 1 reply; 5+ messages in thread From: Alexander Shishkin @ 2009-12-16 13:43 UTC (permalink / raw) To: ben-linux; +Cc: linux-omap, linux-i2c, Alexander Shishkin This is to avoid insanely long lines and levels of indentation. Signed-off-by: Alexander Shishkin <virtuoso@slind.org> CC: linux-i2c@vger.kernel.org CC: linux-omap@vger.kernel.org --- drivers/i2c/busses/i2c-omap.c | 43 ++++++++++++++++++++++------------------ 1 files changed, 24 insertions(+), 19 deletions(-) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index 75bf3ad..ad8242a 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -671,6 +671,27 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id) #define omap_i2c_rev1_isr NULL #endif +/* + * OMAP3430 Errata 1.153: When an XRDY/XDR is hit, wait for XUDF before writing + * data to DATA_REG. Otherwise some data bytes can be lost while transferring + * them from the memory to the I2C interface. + */ +static int omap3430_workaround(struct omap_i2c_dev *dev, u16 *stat, int *err) +{ + while (!(*stat & OMAP_I2C_STAT_XUDF)) { + if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) { + omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY | + OMAP_I2C_STAT_XDR)); + *err |= OMAP_I2C_STAT_XUDF; + return -1; + } + cpu_relax(); + *stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG); + } + + return 0; +} + static irqreturn_t omap_i2c_isr(int this_irq, void *dev_id) { @@ -794,25 +815,9 @@ complete: break; } - /* - * OMAP3430 Errata 1.153: When an XRDY/XDR - * is hit, wait for XUDF before writing data - * to DATA_REG. Otherwise some data bytes can - * be lost while transferring them from the - * memory to the I2C interface. - */ - - if (dev->rev <= OMAP_I2C_REV_ON_3430) { - while (!(stat & OMAP_I2C_STAT_XUDF)) { - if (stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) { - omap_i2c_ack_stat(dev, stat & (OMAP_I2C_STAT_XRDY | OMAP_I2C_STAT_XDR)); - err |= OMAP_I2C_STAT_XUDF; - goto complete; - } - cpu_relax(); - stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG); - } - } + if (dev->rev <= OMAP_I2C_REV_ON_3430 && + omap3430_workaround(dev, &stat, &err)) + goto complete; omap_i2c_write_reg(dev, OMAP_I2C_DATA_REG, w); } -- 1.6.3.3 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH 1/2] omap i2c: make errata 1.153 workaround a separate function 2009-12-16 13:43 ` [PATCH 1/2] omap i2c: make errata 1.153 workaround a separate function Alexander Shishkin @ 2009-12-16 13:43 ` Alexander Shishkin [not found] ` <1260970986-26613-3-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org> 2009-12-16 13:57 ` [PATCH 1/2] omap i2c: make errata 1.153 workaround a separate function Alexander Shishkin 0 siblings, 2 replies; 5+ messages in thread From: Alexander Shishkin @ 2009-12-16 13:43 UTC (permalink / raw) To: ben-linux; +Cc: linux-omap, linux-i2c, Alexander Shishkin From: Alexander Shishkin <ext-alexander.shishkin@nokia.com> This is to avoid insanely long lines and levels of indentation. Signed-off-by: Alexander Shishkin <ext-alexander.shishkin@nokia.com> --- drivers/i2c/busses/i2c-omap.c | 43 ++++++++++++++++++++++------------------ 1 files changed, 24 insertions(+), 19 deletions(-) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index 75bf3ad..ad8242a 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -671,6 +671,27 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id) #define omap_i2c_rev1_isr NULL #endif +/* + * OMAP3430 Errata 1.153: When an XRDY/XDR is hit, wait for XUDF before writing + * data to DATA_REG. Otherwise some data bytes can be lost while transferring + * them from the memory to the I2C interface. + */ +static int omap3430_workaround(struct omap_i2c_dev *dev, u16 *stat, int *err) +{ + while (!(*stat & OMAP_I2C_STAT_XUDF)) { + if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) { + omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY | + OMAP_I2C_STAT_XDR)); + *err |= OMAP_I2C_STAT_XUDF; + return -1; + } + cpu_relax(); + *stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG); + } + + return 0; +} + static irqreturn_t omap_i2c_isr(int this_irq, void *dev_id) { @@ -794,25 +815,9 @@ complete: break; } - /* - * OMAP3430 Errata 1.153: When an XRDY/XDR - * is hit, wait for XUDF before writing data - * to DATA_REG. Otherwise some data bytes can - * be lost while transferring them from the - * memory to the I2C interface. - */ - - if (dev->rev <= OMAP_I2C_REV_ON_3430) { - while (!(stat & OMAP_I2C_STAT_XUDF)) { - if (stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) { - omap_i2c_ack_stat(dev, stat & (OMAP_I2C_STAT_XRDY | OMAP_I2C_STAT_XDR)); - err |= OMAP_I2C_STAT_XUDF; - goto complete; - } - cpu_relax(); - stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG); - } - } + if (dev->rev <= OMAP_I2C_REV_ON_3430 && + omap3430_workaround(dev, &stat, &err)) + goto complete; omap_i2c_write_reg(dev, OMAP_I2C_DATA_REG, w); } -- 1.6.3.3 ^ permalink raw reply related [flat|nested] 5+ messages in thread
[parent not found: <1260970986-26613-3-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org>]
* [PATCH 2/2] omap i2c: add a timeout to the busy waiting [not found] ` <1260970986-26613-3-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org> @ 2009-12-16 13:46 ` Alexander Shishkin 0 siblings, 0 replies; 5+ messages in thread From: Alexander Shishkin @ 2009-12-16 13:46 UTC (permalink / raw) To: ben-linux-elnMNo+KYs3YtjvyW6yDsg Cc: linux-omap-u79uwXL29TY76Z2rM5mHXA, linux-i2c-u79uwXL29TY76Z2rM5mHXA, Alexander Shishkin The errata 1.153 workaround is busy waiting on XUDF bit in interrupt context, which may lead to kernel hangs. The problem can be reproduced by running the bus with wrong (too high) speed. Signed-off-by: Alexander Shishkin <virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org> CC: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org CC: linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org --- drivers/i2c/busses/i2c-omap.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index ad8242a..b474c20 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -678,7 +678,9 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id) */ static int omap3430_workaround(struct omap_i2c_dev *dev, u16 *stat, int *err) { - while (!(*stat & OMAP_I2C_STAT_XUDF)) { + unsigned long timeout = 10000; + + while (!(*stat & OMAP_I2C_STAT_XUDF && --timeout)) { if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) { omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY | OMAP_I2C_STAT_XDR)); @@ -689,6 +691,9 @@ static int omap3430_workaround(struct omap_i2c_dev *dev, u16 *stat, int *err) *stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG); } + if (!timeout) + dev_err(dev->dev, "timeout waiting on XUDF bit\n"); + return 0; } -- 1.6.3.3 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 1/2] omap i2c: make errata 1.153 workaround a separate function 2009-12-16 13:43 ` Alexander Shishkin [not found] ` <1260970986-26613-3-git-send-email-virtuoso-0lOfPCoBze7YtjvyW6yDsg@public.gmane.org> @ 2009-12-16 13:57 ` Alexander Shishkin 1 sibling, 0 replies; 5+ messages in thread From: Alexander Shishkin @ 2009-12-16 13:57 UTC (permalink / raw) To: ben-linux; +Cc: linux-omap, linux-i2c, Alexander Shishkin On Wed, Dec 16, 2009 at 03:43:04 +0200, Alexander Shishkin wrote: > From: Alexander Shishkin <ext-alexander.shishkin@nokia.com> Please disregard this, I've got the emails wrong here. I'll resend shortly. Regards, -- Alex ^ permalink raw reply [flat|nested] 5+ messages in thread
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2009-12-16 13:43 [PATCH 0/2] omap i2c interrupt handler fixes Alexander Shishkin
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2009-12-16 13:46 ` [PATCH 2/2] omap i2c: add a timeout to the busy waiting Alexander Shishkin
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