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SubjectRe: [PATCH v2 5/6] i2c: Add Actions Semi OWL family S900 I2C driver
Hi Andy,

On Sat, Jun 30, 2018 at 03:14:37PM +0300, Andy Shevchenko wrote:
> 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?
>

Fixed in next revision.

> > +#define OWL_I2C_DEFAULT_SPEED 100000
> > +#define OWL_I2C_MAX_SPEED 400000
>
> ..._SPEED -> ..._SPEED_HZ ?
>
> DEFAULT -> DEF ?
>

Okay.

> > +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?
>

I have removed reset function from the interrupt handler and gave the
justification to my reply to Peter's review.

> > + 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.
>

Same as above.

> > + } 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).
>

Same as above.

> > +}
>
> > +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).
>

Same as above.

> > + 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.
>

No. Actually the return path will be fixed in next iteration. Please
see my reply to Peter's review for explanation.

> > + 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
>

Okay.

> > +};
> > +
> > +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.
>

Okay.

Thanks,
Mani

> > +};
>
> --
> With Best Regards,
> Andy Shevchenko

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