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Message-ID: <20240906080749.GE275077@black.fi.intel.com>
Date: Fri, 6 Sep 2024 11:07:49 +0300
From: Mika Westerberg <mika.westerberg@...ux.intel.com>
To: Kimriver Liu <kimriver.liu@...ngine.com>
Cc: jarkko.nikula@...ux.intel.com, andriy.shevchenko@...ux.intel.com,
jsd@...ihalf.com, andi.shyti@...nel.org, linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: designware: fix master is holding SCL low while
ENABLE bit is disabled
Hi,
On Fri, Sep 06, 2024 at 03:47:31PM +0800, Kimriver Liu wrote:
> It was observed issuing ABORT bit(IC_ENABLE[1]) will not work when
> IC_ENABLE is already disabled.
>
> Check if ENABLE bit(IC_ENABLE[0]) is disabled when the master is
> holding SCL low. If ENABLE bit is disabled, the software need
> enable it before trying to issue ABORT bit. otherwise,
> the controller ignores any write to ABORT bit.
>
> Signed-off-by: Kimriver Liu <kimriver.liu@...ngine.com>
>
> ---
> V5->V6: restore i2c_dw_is_master_idling() function checking
> V4->V5: delete master idling checking
> V3->V4:
> 1. update commit messages and add patch version and changelog
> 2. move print the error message in i2c_dw_xfer
> V2->V3: change (!enable) to (!(enable & DW_IC_ENABLE_ENABLE))
> V1->V2: used standard words in function names and addressed review comments
>
> link to V1:
> https://lore.kernel.org/lkml/20240904064224.2394-1-kimriver.liu@siengine.com/
> ---
> drivers/i2c/busses/i2c-designware-common.c | 11 +++++++++++
> drivers/i2c/busses/i2c-designware-master.c | 22 ++++++++++++++++++++++
> 2 files changed, 33 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
> index e8a688d04aee..2b3398cd4382 100644
> --- a/drivers/i2c/busses/i2c-designware-common.c
> +++ b/drivers/i2c/busses/i2c-designware-common.c
> @@ -453,6 +453,17 @@ void __i2c_dw_disable(struct dw_i2c_dev *dev)
>
> abort_needed = raw_intr_stats & DW_IC_INTR_MST_ON_HOLD;
> if (abort_needed) {
> + if (!(enable & DW_IC_ENABLE_ENABLE)) {
> + regmap_write(dev->map, DW_IC_ENABLE, DW_IC_ENABLE_ENABLE);
> + enable |= DW_IC_ENABLE_ENABLE;
> + /*
> + * Wait two ic_clk delay when enabling the I2C to ensure ENABLE bit
> + * is already set by the driver (for 400KHz this is 25us)
> + * as described in the DesignWare I2C databook.
> + */
> + fsleep(25);
> + }
> +
> regmap_write(dev->map, DW_IC_ENABLE, enable | DW_IC_ENABLE_ABORT);
> ret = regmap_read_poll_timeout(dev->map, DW_IC_ENABLE, enable,
> !(enable & DW_IC_ENABLE_ABORT), 10,
> diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
> index c7e56002809a..132b7237c004 100644
> --- a/drivers/i2c/busses/i2c-designware-master.c
> +++ b/drivers/i2c/busses/i2c-designware-master.c
> @@ -253,6 +253,19 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
> __i2c_dw_write_intr_mask(dev, DW_IC_INTR_MASTER_MASK);
> }
>
> +static bool i2c_dw_is_master_idling(struct dw_i2c_dev *dev)
> +{
> + u32 status;
> +
> + regmap_read(dev->map, DW_IC_STATUS, &status);
> + if (!(status & DW_IC_STATUS_MASTER_ACTIVITY))
> + return true;
> +
> + return !regmap_read_poll_timeout(dev->map, DW_IC_STATUS, status,
> + !(status & DW_IC_STATUS_MASTER_ACTIVITY),
> + 1100, 20000);
> +}
Yeah, I now realize that i2c_dw_wait_bus_not_busy() checks for
DW_IC_STATUS_ACTIVITY not for DW_IC_STATUS_MASTER_ACTIVITY as I thought
so consolidating them makes not that much sense.
This looks good to me,
Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
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