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Date: Sat, 07 Jun 2014 02:26:29 +0100 From: Ben Hutchings <ben@...adent.org.uk> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org CC: akpm@...ux-foundation.org, "Wolfram Sang" <wsa@...-dreams.de>, "Du, Wenkai" <wenkai.du@...el.com>, "Mika Westerberg" <mika.westerberg@...ux.intel.com> Subject: [PATCH 3.2 70/92] i2c: designware: Mask all interrupts during i2c controller enable 3.2.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: "Du, Wenkai" <wenkai.du@...el.com> commit 47bb27e78867997040a228328f2a631c3c7f2c82 upstream. There have been "i2c_designware 80860F41:00: controller timed out" errors on a number of Baytrail platforms. The issue is caused by incorrect value in Interrupt Mask Register (DW_IC_INTR_MASK) when i2c core is being enabled. This causes call to __i2c_dw_enable() to immediately start the transfer which leads to timeout. There are 3 failure modes observed: 1. Failure in S0 to S3 resume path The default value after reset for DW_IC_INTR_MASK is 0x8ff. When we start the first transaction after resuming from system sleep, TX_EMPTY interrupt is already unmasked because of the hardware default. 2. Failure in normal operational path This failure happens rarely and is hard to reproduce. Debug trace showed that DW_IC_INTR_MASK had value of 0x254 when failure occurred, which meant TX_EMPTY was unmasked. 3. Failure in S3 to S0 suspend path This failure also happens rarely and is hard to reproduce. Adding debug trace that read DW_IC_INTR_MASK made this failure not reproducible. But from ISR call trace we could conclude TX_EMPTY was unmasked when problem occurred. The patch masks all interrupts before the controller is enabled to resolve the faulty DW_IC_INTR_MASK conditions. Signed-off-by: Wenkai Du <wenkai.du@...el.com> Acked-by: Mika Westerberg <mika.westerberg@...ux.intel.com> [wsa: improved the comment and removed typo in commit msg] Signed-off-by: Wolfram Sang <wsa@...-dreams.de> Signed-off-by: Ben Hutchings <ben@...adent.org.uk> --- drivers/i2c/busses/i2c-designware-core.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/i2c/busses/i2c-designware-core.c +++ b/drivers/i2c/busses/i2c-designware-core.c @@ -346,6 +346,9 @@ static void i2c_dw_xfer_init(struct dw_i ic_con &= ~DW_IC_CON_10BITADDR_MASTER; dw_writel(dev, ic_con, DW_IC_CON); + /* enforce disabled interrupts (due to HW issues) */ + i2c_dw_disable_int(dev); + /* Enable the adapter */ dw_writel(dev, 1, DW_IC_ENABLE); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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