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SubjectRe: [PATCH v2 5/6] i2c: Add Actions Semi OWL family S900 I2C driver
On Thu, Jun 28, 2018 at 9:10 PM, Manivannan Sadhasivam
<manivannan.sadhasivam@linaro.org> wrote:
> Add Actions Semi OWL family S900 I2C driver.

> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>

> +#include <linux/io.h>

Perhaps keep in order?

> +#define OWL_I2C_DEFAULT_SPEED 100000
> +#define OWL_I2C_MAX_SPEED 400000

..._SPEED -> ..._SPEED_HZ ?

DEFAULT -> DEF ?

> +static int owl_i2c_reset(struct owl_i2c_dev *i2c_dev)
> +{
> + unsigned int val, timeout = 0;
> +
> + owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
> + OWL_I2C_CTL_EN, false);

> + mdelay(1);

1 ms keeping CPU busy for nothing. Perhaps usleep_range() / msleep()?
Is it called in atomic context?

> + owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
> + OWL_I2C_CTL_EN, true);
> +
> + /* Reset FIFO */
> + owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
> + OWL_I2C_FIFOCTL_RFR | OWL_I2C_FIFOCTL_TFR,
> + true);
> +
> + /* Wait 50ms for FIFO reset complete */
> + do {
> + val = readl(i2c_dev->base + OWL_I2C_REG_FIFOCTL);
> + if (!(val & (OWL_I2C_FIFOCTL_RFR | OWL_I2C_FIFOCTL_TFR)))
> + break;

> + mdelay(1);

Ditto.

> + } while (timeout++ < OWL_I2C_MAX_RETRIES);

OK, I see you call it from IRQ context. 50ms for IRQ handler is
inappropriate. (1ms either, but at least not so drastically).

> +}

> +static irqreturn_t owl_i2c_interrupt(int irq, void *_dev)
> +{

> + stat = readl(i2c_dev->base + OWL_I2C_REG_STAT);
> + if (stat & OWL_I2C_STAT_BEB) {
> + dev_dbg(&i2c_dev->adap.dev, "bus error");

> + owl_i2c_reset(i2c_dev);

This is questionable to be here (looking at so loong delays in it).

> + goto stop;
> + }

> + return IRQ_HANDLED;
> +}

> +static int owl_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> + int num)
> +{

> + int ret = 0, idx;

Redundant assignment.

> + ret = owl_i2c_hw_init(i2c_dev);
> + if (ret)
> + return ret;

> +}

> +static const struct i2c_algorithm owl_i2c_algorithm = {
> + .master_xfer = owl_i2c_master_xfer,

> + .functionality = owl_i2c_func

Slightly better to keep comma at the end

> +};
> +
> +static const struct i2c_adapter_quirks owl_i2c_quirks = {
> + .flags = I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST,
> + .max_read_len = 240,
> + .max_write_len = 240,
> + .max_comb_1st_msg_len = 6,
> + .max_comb_2nd_msg_len = 240

Ditto.

> +};

--
With Best Regards,
Andy Shevchenko

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