On Tue, Apr 13, 2021 at 8:10 AM Chris Packham
<chris.pack...@alliedtelesis.co.nz> wrote:
>
> The fsl-i2c controller will generate an interrupt after every byte
> transferred. Make use of this interrupt to drive a state machine which
> allows the next part of a transfer to happen as soon as the interrupt is
> received. This is particularly helpful with SMBUS devices like the LM81
> which will timeout if we take too long between bytes in a transfer.
Also see my other comments below.
...
> +// SPDX-License-Identifier: GPL-2.0
I think it is better to split this with a removal of old stuff and
updating a copyright notice and go as a last one in the series.
...
> +static char *action_str[] = {
static const char * const action_str[]
> + "invalid",
> + "start",
> + "restart",
> + "read begin",
> + "read",
> + "write",
> + "stop",
> +};
...
> + dev_dbg(i2c->dev, "%s: action = %s\n", __func__,
> + action_str[i2c->action]);
Drop useless __func__. With Dynamic Debug enabled it can be turned on
and off at run time.
...
> + /* Generate txack on next to last byte */
Tx ACK ? Ditto for other comments.
...
> + dev_dbg(i2c->dev, "%s: %s %02x\n", __func__,
> + action_str[i2c->action], byte);
You already printed action. Anything changed?
> + dev_dbg(i2c->dev, "%s: %s %02x\n", __func__,
> + action_str[i2c->action], msg->buf[i2c->byte_posn]);
Deduplicate this. Perhaps at the end of switch-case print once with
whatever temporary variable value you want to.
...
> + case MPC_I2C_ACTION_INVALID:
> + default:
Does the first one deserve loud WARN?
Otherwise, why is it defined at all?
> + WARN(1, "Unexpected action %d\n", i2c->action);
> + break;
...
> +static void mpc_i2c_do_intr(struct mpc_i2c *i2c, u8 status)
> {
> + spin_lock_irqsave(&i2c->lock, flags);
Why _irqsave?
...
> + dev_dbg(i2c->dev, "arbiritration lost\n");
arbitration
...
> + if (i2c->expect_rxack && (status & CSR_RXAK)) {
> + dev_dbg(i2c->dev, "no RXAK\n");
You see, you have to be consistent in comments and messages.
Either use TXAK/RXAK, or more verbose 'Tx ACK/Rx ACK' everywhere.
...
> +out:
out_unlock:
> + spin_unlock_irqrestore(&i2c->lock, flags);
...
> +static irqreturn_t mpc_i2c_isr(int irq, void *dev_id)
> +{
> + struct mpc_i2c *i2c = dev_id;
> + u8 status = readb(i2c->base + MPC_I2C_SR);
I would split this assignment, so it will be closer to its user.
> + if (status & CSR_MIF) {
> + writeb(0, i2c->base + MPC_I2C_SR);
> + mpc_i2c_do_intr(i2c, status);
> + return IRQ_HANDLED;
> }
> + return IRQ_NONE;
> +}
...
> + time_left = wait_event_timeout(i2c->waitq, !i2c->block,
> i2c->adap.timeout);
> +
No need for a blank line here.
> + if (!time_left)
> + i2c->rc = -ETIMEDOUT;
> + else if (time_left < 0)
Redundant 'else'
> + i2c->rc = time_left;
Can't you return an error code from here, rather than injecting it
somewhere where it doesn't belong to?
> }
--
With Best Regards,
Andy Shevchenko
