Hi,
Alexander Shishkin wrote:
> 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@xxxxxxxxx>
> Acked-by: Tony Lindgren <tony@xxxxxxxxxxx>
> CC: linux-i2c@xxxxxxxxxxxxxxx
> CC: linux-omap@xxxxxxxxxxxxxxx
> CC: nm@xxxxxx
> ---
> drivers/i2c/busses/i2c-omap.c | 8 ++++++++
> 1 files changed, 8 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index 2d146ac..7d56a25 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -678,6 +678,8 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id)
> */
> static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
> {
> + unsigned long timeout = jiffies + msecs_to_jiffies(1);
> +
> 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 |
> @@ -685,6 +687,12 @@ static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err)
> *err |= OMAP_I2C_STAT_XUDF;
> return -ETIMEDOUT;
> }
> +
> + if (time_after(jiffies, timeout)) {
This is called from hard interrupt context, so we cannot use jiffies.
> + dev_err(dev->dev, "timeout waiting on XUDF bit\n");
> + return 0;
> + }
> +
> cpu_relax();
> *stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
> }
A.
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