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SubjectRe: [PATCH v4 RESEND] pwm: atmel: add Timer Counter Block PWM driver
On Thu, Dec 20, 2012 at 10:12:56AM +0100, Boris BREZILLON wrote:
> Hi,
>
> Sorry for resend. The previous version still has alignment issues on
> atmel_tcb_pwm_set_polarity, atmel_tcb_pwm_request and
> atmel_tcb_pwm_config function parameters.
>
> This patch adds a PWM driver based on Atmel Timer Counter Block.
> Timer Counter Block is used in Waveform generator mode.
>
> A Timer Counter Block provides up to 6 PWM devices grouped by 2:
> * group 0 = PWM 0 and 1
> * group 1 = PWM 1 and 2
> * group 2 = PMW 3 and 4

Should this be "PWM 2 and 3" and "PWM 4 and 5"? Or is PWM 1 shared
between groups 0 and 1?

> +static int atmel_tcb_pwm_request(struct pwm_chip *chip,
> + struct pwm_device *pwm)
> +{
[...]
> + clk_enable(tc->clk[group]);

You need to check the return value of clk_enable(). There's always a
small possibility that it may fail.

> +static void atmel_tcb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
[...]
> + /* If duty is 0 reverse polarity */
> + if (tcbpwm->duty == 0)
> + polarity = !polarity;

Rather than commenting on what the code does, this should say why it
does so.

> +static int atmel_tcb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
[...]
> + /* If duty is 0 reverse polarity */
> + if (tcbpwm->duty == 0)
> + polarity = !polarity;

Same here.

> +static int atmel_tcb_pwm_probe(struct platform_device *pdev)
> +{
[...]
> + struct atmel_tcb_pwm_chip *tcbpwm;
> + struct device_node *np = pdev->dev.of_node;
> + struct atmel_tc *tc;
> + int err;
> + int tcblock;
> +
> + err = of_property_read_u32(np, "tc-block", &tcblock);
> + if (err < 0) {
> + dev_err(&pdev->dev,
> + "failed to get tc block number from device tree (error: %d)\n",

Maybe: "failed to get Timer Counter Block number..." to make it
consistent with the error message below:

> + tc = atmel_tc_alloc(tcblock, "tcb-pwm");
> + if (tc == NULL) {
> + dev_err(&pdev->dev, "failed to allocate Timer Counter Block\n");
> + return -ENOMEM;
> + }
[...]
> +static const struct of_device_id atmel_tcb_pwm_dt_ids[] = {
> + { .compatible = "atmel,tcb-pwm", },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids);

This is still wrong.

> +static struct platform_driver atmel_tcb_pwm_driver = {
> + .driver = {
> + .name = "atmel-tcb-pwm",
> + .of_match_table = atmel_tcb_pwm_dt_ids,
> + },
> + .probe = atmel_tcb_pwm_probe,
> + .remove = atmel_tcb_pwm_remove,
> +};
> +module_platform_driver(atmel_tcb_pwm_driver);
> +
> +MODULE_AUTHOR("Boris BREZILLON <b.brezillon@overkiz.com>");
> +MODULE_DESCRIPTION("Atmel Timer Counter Pulse Width Modulation Driver");
> +MODULE_ALIAS("platform:atmel-tcb-pwm");

I don't think you needMODULE_ALIAS() if the alias is the same as the
driver name.

Thierry
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