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Date: Wed, 10 May 2017 16:13:01 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Tim Sander <tim@...eglstein.org>,
Phil Reid <preid@...ctromag.com.au>
Cc: Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
Wolfram Sang <wsa@...-dreams.de>, linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c-designware: add i2c gpio recovery option
On Wed, 2017-05-10 at 13:57 +0200, Tim Sander wrote:
> This patch contains much input from Phil Reid and has been tested
> on Intel/Altera Cyclone V SOC Hardware with Altera GPIO's for the
> SCL and SDA GPIO's. I am still a little unsure about the recover
> in the timeout case (i2c-designware-core.c:770) as i could not
> test this codepath.
Since it's not an RFC anymore let me do some comments on the below.
> @@ -317,6 +317,7 @@ static void i2c_dw_release_lock(struct dw_i2c_dev
> *dev)
> dev->release_lock(dev);
> }
>
> +
> /**
> * i2c_dw_init() - initialize the designware i2c master hardware
> * @dev: device private data
This doesn't belong to the change.
> @@ -463,7 +464,12 @@ static int i2c_dw_wait_bus_not_busy(struct
> dw_i2c_dev *dev)
> while (dw_readl(dev, DW_IC_STATUS) & DW_IC_STATUS_ACTIVITY) {
> if (timeout <= 0) {
> dev_warn(dev->dev, "timeout waiting for bus
> ready\n");
> - return -ETIMEDOUT;
> + i2c_recover_bus(&dev->adapter);
> +
> + if (dw_readl(dev, DW_IC_STATUS) &
> DW_IC_STATUS_ACTIVITY)
> + return -ETIMEDOUT;
> + else
Redundant.
> + return 0;
> }
Actually I would rather refactor first above function:
1) to be do {} while();
2) to have invariant condition out of the loop.
> timeout--;
> usleep_range(1000, 1100);
> @@ -719,9 +725,10 @@ static int i2c_dw_handle_tx_abort(struct
> dw_i2c_dev *dev)
> for_each_set_bit(i, &abort_source, ARRAY_SIZE(abort_sources))
> dev_err(dev->dev, "%s: %s\n", __func__,
> abort_sources[i]);
>
> - if (abort_source & DW_IC_TX_ARB_LOST)
> + if (abort_source & DW_IC_TX_ARB_LOST) {
> + i2c_recover_bus(&dev->adapter);
> return -EAGAIN;
> - else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
> + } else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
> return -EINVAL; /* wrong msgs[] data */
> else
Both else:s are redundant.
if (abort_source & DW_IC_TX_ARB_LOST) {
i2c_recover_bus(&dev->adapter);
return -EAGAIN;
}
if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
...
Though I may agree on leaving them here for sake of keeping less lines
of code.
> return -EIO;
> +#include <linux/gpio.h>
I think it should be
#include <linux/gpio/consumer.h>
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -41,6 +41,7 @@
> #include <linux/reset.h>
> #include <linux/slab.h>
> #include <linux/acpi.h>
> +#include <linux/of_gpio.h>
No, please don't.
In recent code we try to avoid OF/ACPI/platform specific bits if there
is a common resource provider (and API) for that. GPIO is the case.
> +void i2c_dw_unprepare_recovery(struct i2c_adapter *adap)
> +{
> +}
> +
> +
Remove extra line.
> +static int i2c_dw_get_scl(struct i2c_adapter *adap)
> +{
> + struct platform_device *pdev = to_platform_device(&adap->dev);
> + struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
struct dw_i2c_dev *dev = i2c_get_adapdata(adap); ?
Ditto for all occurrences in the code.
> +
> + return gpiod_get_value_cansleep(dev->gpio_scl);
> +}
> +static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev,
> + struct i2c_adapter *adap)
> +{
> + struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
> +
> + dev->gpio_scl = devm_gpiod_get_optional(dev->dev,
> + "scl",
> + GPIOD_OUT_HIGH);
> + if (IS_ERR_OR_NULL(dev->gpio_scl))
This is wrong. You should not use this macro in most cases. And
especially it breaks the logic behind _optional().
> + return PTR_ERR(dev->gpio_scl);
> +
> + dev->gpio_sda = devm_gpiod_get_optional(dev->dev, "sda",
> GPIOD_IN);
> + if (IS_ERR_OR_NULL(dev->gpio_sda))
Ditto.
> + return PTR_ERR(dev->gpio_sda);
> + rinfo->scl_gpio = desc_to_gpio(dev->gpio_scl);
> + rinfo->sda_gpio = desc_to_gpio(dev->gpio_sda);
Why?!
> +};
> @@ -285,6 +368,7 @@ static int dw_i2c_plat_probe(struct
> platform_device *pdev)
> adap->class = I2C_CLASS_DEPRECATED;
> ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
> adap->dev.of_node = pdev->dev.of_node;
> + snprintf(adap->name, sizeof(adap->name), "Designware i2c
> adapter");
It looks like a separate change.
>
> + r = i2c_dw_init_recovery_info(dev, adap);
> + if (r == -EPROBE_DEFER)
Remove extra space.
> + goto exit_probe;
> +
> r = i2c_dw_probe(dev);
> if (r)
> goto exit_probe;
>
> - return r;
> + return 0;
Doesn't belong to the change.
Don't change arbitrary typos or do small "improvements" in the change
which is not about them.
--
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy
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