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SubjectRe: [PATCH v4 RESEND] pwm: atmel: add Timer Counter Block PWM driver
On 08/01/2013 08:10, Thierry Reding wrote:
> 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:

Do I have to break the error string so that the line does not exceed 80 characters ?
Checkpath script does not complain about it, and the CodingStyle file specify that visible
strings should not be broken...

Same question applies to this error, which I converted to a multi-line error in a previous patch version:

dev_err(chip->dev,
"failed to configure period_ns:\n"
"the other PWM device in this group is already\n"
"configured with a different period_ns value\n");



>
>> + 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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